THE PROJECT FOR THE PLANNING OF THE NADI RIVER FLOOD ... · The Project for the Planning of the...
Transcript of THE PROJECT FOR THE PLANNING OF THE NADI RIVER FLOOD ... · The Project for the Planning of the...
THE REPUBLIC OF FIJI MINISTRY OF AGRICULTURE, RURAL AND MARITIME DEVELOPMENT AND NATIONAL DISASTER MANAGEMENT
THE PROJECT FOR THE PLANNING OF
THE NADI RIVER FLOOD CONTROL
STRUCTURES
VOLUMEⅡ MAIN REPORT
PARTⅡ: FEASIBILITY STUDY
JULY 2016
JAPAN INTERNATIONAL COOPERATION AGENCY (JICA)
YACHIYO ENGINEERING CO., LTD. CTI ENGINEERING INTERNATIONAL CO., LTD. GE
CR(1)
16-091
THE REPUBLIC OF FIJI
THE PROJECT FOR THE PLANNING OF
THE NADI RIVER FLOOD CONTROL STRUCTURES
COMPOSITION OF FINAL REPORT
VOLUME I SUMMARY
VOLUME II MAIN REPORT
PartⅠ MASTER PLAN STUDY
PartⅡ FEASIBILITY STUDY
VOLUME I Ⅲ DATA BOOK
PartⅠ DATA BOOK (1)
PartⅡ DATA BOOK (2)
Exchange Rate: FJD 1 = JPY 54.5, 1 USD=FJD 2.17
(As of April, 2016)
<Map of Project Area>
(出典)Integrated Water Resource Management Demonstration Project
(ビチレブ島)
Namosi River
Nawaka River
Malakua River
Nadi River
Nadi Bay
Photo
Photo-1 Inception Report Meeting Photo-2 Nadi River Basin (Upstream)
Photo-3 Nadi River Basin(Panoramic view) Photo-4 Nadi River (River Mouth)
Photo-5 Central of Nadi Town Photo-6 Nadi River (Middle Stream)
Photo-7 Nadi River (Upstream) Photo-8 Vaturu Dam (Nadi River Upstream)
Nadi River River Mouth
Nadi Bay
Denarau Area Central of Nadi Town
Nadi River
Photo-9 Nadi River(Nadi Town Bridge) Photo-10 Nadi River(Nadi Town Bridge)during Flood
Photo-11 Nadi River(Old Queens Road Bridge) Photo-12 Nadi River(Old Queens Road Bridge)during Flood
Photo-13 Nawaka River Photo-14 Retention Dam(Nawaka River)
Photo-15 Counterpart Training in Japan Photo-16 Seminar in Fiji
Nadi River
Water Level Gauge
Nadi River
Nadi River Nadi River
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Executive Summary of
Flood Control Master Plan and Priority Project
in Nadi River Basin
1. Master Plan
【Basic Concept of Master Plan】
- In the Master Plan, based on the flood and river basin characteristics as well as properties in the
upstream, midstream and downstream of the Nadi River, taking into account measures in an entire
basin, comprehensive flood control plan consisting of dam, river improvement, retarding basins and
ring dikes are proposed.
- Taking into account a long term and the large budget to complete the structural measures, and also
taking into account the risk due to flood exceeding design scale, perfect protection measures for
flood inundation are not feasible. Therefore, structural measures and non-structural measures such
are proposed in the Master Plan..
- In the formulation of the Master Plan, it is an important to clarify priority protected areas from the
view point of clarification on the contents of flood control plan and addressing a road map for the
integration of short, middle and long term flood control plan. Therefore, Important Protected Area is
set and it is prioritized to be mitigated from damage by flood.
- The Master Plan is formulated considering Environmental and Social Considerations and Social
Acceptance for flood control
【Target Area of Master Plan】
Target area of Master Plan is Nadi River Basin with catchment area of 516 km2.
【Target Scale of Master Plan】
Design flood scale for Master Plan is set as 1/50 with regard to previous maximum flood event occurred
in March 2012.
【Components of Master Plan】
(1) Structural Measures
Structural Measures as shown in Figure1 and Table1 are proposed in order to mitigate flood damage by
targeted flood in Nadi River Basin.
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Figure 1 Components of Master Plan (Structural Measures)
Table 1 Components of Master Plan (Structural Measures)
1. Nadi River Downstream (1) Retarding Basin and River
Improvement in downstream
A=725 ha
V=9,715 千m3-
(2) Ring Dike L=1.8 km -Middlestream (3) River Widening
2) L=13 km
(4) Retarding Basin A A=35 ha
V=795 千m3
Retarding Basin B A=178 ha
V=6,920 千m3
Upstream (5) Dam and River improvement in
upstream 1
2. Tributaries (6) River Improvement L=21 km
Retarding Basins (13 sites) A=340 ha
V=11,600 千m3
River, LocationComponent of
the Master PlanQuantities Remarks
Structural
Measures
Including rebuilding of 2
(two) bridges
-
Nawaka
Maralua
Namosi
River
Including rebuilding of 4
(four) bridges in
tributaries
(2)
(3)
(4)
(5)
(6)
(1) :Retarding Basin in downstream incl. surrounding dike of retarding basin in downstream:River Improvement in downstream
:Ring Dike
:River Widening incl. Rebuilding of 2(two) bridges
:Retarding Basin A,B in upstream
:Dam
:River improvement in upstream
:Retarding Basins in Tributaries incl. surrounding dike
:River Improvement in Tributaries incl. Rebuilding of 4(four) bridges
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(2) Non-Structural Measures
Non-Structural Measures as shown in Table2 are proposed in order to corroborate and complement structural
measures and mitigate damage by targeted flood.
Table 2 Components of Master Plan (Non-Structural Measures)
Effect of Measure
(Large Classification) Major components
Non-Structural
Measures
(1) Understanding disaster risk and risk
avoidance
1-1) Strengthening of understanding flood risk with flood
hazard map
1-2) Strengthening flood forecasting technology
(2) Enhancing disaster preparedness for
effective response
2-1) Strengthening disaster management system
(3) Disaster risk management, risk
avoidance
3-1) Technical assistant for land-use regulation
3-2) Strengthening river basin management
(4) Economic disaster risk management 4-1) Strengthening economic disaster risk management by
regional BCP
(5) Evaluation and feedback 5-1) Establishing a system of evaluation of Pre-disaster
activity / existing measures and feedback
【Implementation Schedule of Master Plan】
Proposed entire implementation schedule of the Master Plan projects is shown in Table3. Target
implementation period of Master Plan is proposed as 30 years from the project commencement.
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Table 3 Components of Master Plan and Implementation Schedule (Proposed)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Study on M/P
Detailed Design
1 River channel widening works in midstream section
1) River channel widening works in midstream section, L=13km
2 Retarding basin works in upstream section
1) Retarding basin (A) works in right bank side in Nadi River, A=35ha
2) Retarding basin (B) works in left bank side in Nadi River, A=178ha
3 Ring dike
1) Ring dike, L=1.8km
4 Shortcut in tributaries / Surrounding dike works in Nadi River
1) Shortcut in tributaries, A=0.5km
2) Surrounding dike, L=4.5km
1 Retarding Basin in downstream section (A=km2)
1) Retarding Basin in downstream section, A=725ha
2 River improvement in tributaries
1) Nawaka River, L=8.5km
2) Malakua River , L=8.5km
3) Namosi River , L=4.0km
1 Dam construction in upstream in Nadi River (H= m)
1) Dam construction in upstream in Nadi River
1 Understanding disaster risk and risk avoidance
1-1) Strengthening of understanding flood risk with flood hazard map
1-2) Strengthening flood forecasting technology
2 Enhancing disaster preparedness for effective response
2-1) Strengthening disaster management system
2-2) Strengthening emergency assistance system
3 Disaster risk management, risk avoidance
3-1) Land use regulations
3-2) Strengthening river basin management
4 Economic disaster risk management
4-1) Strengthening economic disaster risk management by regional BCP
5 Establishing a system of evaluation of Pre-disaster activity / existing measures and feedback
5-1) Establishing a system of evaluation of Pre-disaster activity / existing measures and feedback
Note: *including loan agreement, EIA, land acquisition, procurement of consultant (D/D, C/S), detailed design, preparation of PQ and tender document and so on.
20XX-20XX 20XX-20XX
I. Structural Measures
I-B. Middle Term Measures
I-C. Long Term Measures
II. Non-structural Measures
I-A. Priority Project (Short Term Measures)
Work Item
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2.Priority Project
【Basic Concept for selection of Priority Project】
- Taking into account a long term and the large budget to complete the structural measures, and also
taking into account the risk due to flood exceeding design scale, perfect protection measures for
flood inundation are not feasible. Therefore, Priority Project is selected in order to protect important
area and mitigate flood damage.
- Regarding structural measures of Priority Project, components which mitigate flood damage in
Important Protected Area is selected after setting Important Protected Area.
- Regarding non-structural measures of Priority Project, protection of human lives, understanding of
disaster risks and evacuation are considered as a top priority. Based on this concept, components for
understanding of disaster risks and evacuation are selected as Priority Project.
【Components of Priority Project】
(1) Structural Measures
Structural Measures as shown in Figure 3 and Table 4 are proposed in order to mitigate flood damage in
Important Protected Area (Figure 2).
Figure 2 Important Protected Area
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S
Malakua River
⑥Rebuilding of Bridge ①River Widening: L=13km
① River Widening
② Retarding Basin A, B
③ Surrounding Dike
④ Ring Dike
⑤ Shortcut of tributaries
⑥ Rebuilding of Bridge (Nadi town bridge)
⑦ Rebuilding of Bridge (Old Queens Road bridge)
Component
②Retarding Basin A: A=35haRetarding Basin B: A=178ha
(Water Surface Area in flooding)
⑥Rebuilding of Bridge: L=108m
⑦Rebuilding of Bridge: L=96m
③Surrounding Dike: L=4.5km
④Ring Dike: L=1.8km
⑤Shortcuts: L=0.5km
Figure 3 Components of Priority Project (Structural Measures)
Table 4 Components of Priority Project (Structural Measures)
Quantities
1. Nadi River Downstream (1) Retarding Basin and River
Improvement in downstream - -
(2) Ring Dike ④ Ring Dike L=1.8 km -Middlestream (3) River Widening
2) ① River Widening
Rebuilding of Nadi TOwn Bridge
Rebuilding of Old Queens Road Bridge
L=13 km
L=108 m
L= 96 m
(4) Retarding Basin A ② Retarding Basin A A=35 ha
V=795 千m3
Retarding Basin B ② Retarding Basin B A=178 ha
V=6,920 千m3
Upstream (5) Dam and River improvement in
upstream -
2. Tributaries (6) River Improvement ⑤③-2
Shortsut of Tributaries
Surrounding Dike of Nadi Town
L=0.5 km
L=4.5 km
Retarding Basins (13 sites)-
Shortcut and Surrounding dike in
tributaries are preceded to
construction as part of the master
plan―
Component of the Priority ProjectRemarks
Main Component
Structural
Measures ―
-
-
―
Nawaka
Maralua
Namosi
River
River, LocationComponent of
the Master Plan
(2) Non-Structural Measures
Protection of human lives, understanding of disaster risks and evacuation are considered as a top priority,
under condition that the progress of structural measures project will be at initial phase. Therefore, activities
accompanied with development and disclosure of hazard maps and development of hydrological devices for
awareness of flood risks are proposed as Priority project. In addition, in order to evaluate the effect of
non-structural measures in the past or priority projects, and in order to connect to “Better disaster prevention”,
evaluation and feedback system on the past projects is also proposed as Priority Project.
Component
① River Widening
② Retarding Basin A, B
③ Srrounding Dike
④ Ring Dike
⑤ Shortcut in tributaries
⑥ Rebuilding of Bridges
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Table 5 Components of Priority Project (Non-Structural Measures)
Category Measures Non-structural Measures
Understanding disaster risk and risk avoidance
Strengthening of understanding flood risk with flood hazard map
Strengthening flood forecasting technology, such as expansion of rainfall gauge, water level gauge and introduction of real-time monitoring camera
Better Disaster Prevention Establishing a system of evaluation of Pre-disaster activity / existing measures and feedback
【Selection of Implementation Project】
Integrated flood control facilities considering whole river basin have not been installed yet in spite of effectiveness of structural measures and implementation of structural measures such as dam, retarding basin, and river are required urgently. Therefore, structural measures of Priority Project are selected as Implementation Project.
【Objective of Implementation Project】
Objective of Implementation Project is to improve of vulnerability to flood in Nadi River Basin, mitigate flood damage specially in Important Protected Area and contribute to improve living environment of residents by developing flood control facilities such as river widening and retarding basin in Nadi River Basin, which has been damaged by severe flood.
【Components of Implementation Project】
Components of Implementation Project is as shown in Figure 4 and Table 6, which are as same as structural measures of Priority Project.
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S
Malakua River
⑥Rebuilding of Bridge ①River Widening: L=13km
① River Widening② Retarding Basin A, B③ Surrounding Dike④ Ring Dike⑤ Shortcut of tributaries⑥ Rebuilding of Bridge (Nadi town bridge)⑦ Rebuilding of Bridge (Old Queens Road bridge)
Component
②Retarding Basin A: A=35haRetarding Basin B: A=178ha
(Water Surface Area in flooding) ⑥Rebuilding of Bridge: L=108m
⑦Rebuilding of Bridge: L=96m③Surrounding Dike: L=4.5km
④Ring Dike: L=1.8km
⑤Shortcuts: L=0.5km
Figure 4 Components of Implementation Project (Structural Measures)
Table 6 Components of Implementation Project (Structural Measures)
Quantities1. Nadi River Downstream (1) Retarding Basin and River
Improvement in downstream - -
(2) Ring Dike ④ Ring Dike L=1.8 km -
Middlestream (3) River Widening2) ① River WideningRebuilding of Nadi TOwn BridgeRebuilding of Old Queens Road Bridge
L=13 kmL=108 mL= 96 m
(4) Retarding Basin A ② Retarding Basin A A=35 haV=795 千m3
Retarding Basin B ② Retarding Basin B A=178 haV=6,920 千m3
Upstream (5) Dam and River improvement inupstream -
2. Tributaries (6) River Improvement ⑤③-2
Shortsut of TributariesSurrounding Dike of Nadi Town
L=0.5 kmL=4.5 km
Retarding Basins (13 sites)-
Shortcut and Surrounding dike intributaries are preceded toconstruction as part of the masterplan―
Component of the Priority ProjectRemarks
Main ComponentStructuralMeasures ―
-
-
―
NawakaMaraluaNamosiRiver
River, Location Component ofthe Master Plan
【Implementation Schedule of Implementation Project】
Implementation Schedule of Implementation Project is as shown in Table 8.
【Implementation Project 】
Implementation Project Cost is as shown in Table 9.
Component① River Widening② Retarding Basin A, B③ Srrounding Dike④ Ring Dike⑤ Shortcut in tributaries⑥ Rebuilding of Bridges
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【Economic Feasibility of Implementation Project】
Total cost of the priority project is JPY21.0 billion (F$385million) and the average annual benefit is JPY 1.88billion (F$34.5million). These figures lead to EIRR 12.0%, B/C=1.2 and NPV JPY1.8billion (F$33million) respectively. This economic valuation is beyond the target investment rate of 10% in Fiji and show the adequate economic effect.
Table 7 Result of Economic Evaluation
Economic indicator Result Evaluation
Economic internal rate of return (EIRR)
12.0% Since EIRR is well over 10% which is applied to the development assistance project in Fiji, the economic effectiveness is high.
Benefit-cost (B/C) ratio 1.20 Since the B/C ratio is over 1.0, the cost-effectiveness is high.
Net present value (NPV) JPY 1.8 billion (FJD33 million)
Since the value is plus, the cost-effectiveness is high.
Source: JICA study team
【Conclusion and Recommendation】
Implementation Project proposed as one of the Priority Project is evaluate appropriate since it could mitigate severe flood damage and it is feasible technically, economically, socially and environmentally. Therefore, next steps such as securing budget and request for technical assistance as follows are recommended to be conducted by Fiji Government as soon.
(1) Implementation of the Priority Project and establishment of Implementation Structure
(2) Formulation consensus of Government and residents for the Implementation
(3) Commencement of loan procedure for project fund
(4) Commencement of negotiation for land acquisition and compensation
(5) Commencement of consultant procurement and environmental monitoring
(6) Establishment of legislation of flood control
(7) Preparation and consolidation of organization responsible for flood control and capacity building
(8) Preparation of criteria and standard
(9) Permanent securement of maintenance budget for flood control
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Table 8 Implementation Schedule of Implementation Project (Proposed)
Implementation ScheduleMonth
8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7
1
1
1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1
1 1 1
1 1
1 1
1
1 1
1
1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
501 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
261 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
261 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
381 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
7 0 0 0 0 0
0 6 12 12 8 0Package 4 Surrounding Dike
0 0 0 0
6 12 8 0 0Package 3 Ring Dike
0 0 0 0 0
6 12 8 0 0 0Package 2 Retarding Basin
0 0 0 0
12 12 12 8 0Package 1 River Widening
0 0 0 0 6
Land Acquisition 350 4 12 12
Construction Supervision (50 months) 50
Project Management Unit Supporting (84 months) 84
0
Consulting Services (84 months) 84
Detailed Design (12 months) 12
Tender Assistance (12 months) 12
Pledge 1
Signing of Loan Agreement 1
0
Opening of L/C and Ussurance of L/Com (1 month) 1
Selection of Consultant (12 months) 12
0
2021 2022 2023 20242015 2016 2017 2018 2019 2020
Tender Assistance (12 months) 12
Preparation of Bid Document & JICA Concurrence (3 months) 3
Tender Period (2 months) 2
JICA Approval of Contract (1 month) 1
Evaluation of Bids (2months) 2
JICA Concurrence of Bid Evaluation (1 month) 1
Contract Negotiation (2 months) 2
Defect Liability Period
Defect Liability Period
Defect Liability Period
Defect Liability Period
*Year in above table shows the fiscal year of Fiji (August 1st to July 31th of following year)
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Table 9 Project Cost of Implementation Project
(FC&Total: Million JPY, LC: Million FJD)
FC LCmillion(Yen)
million(F$)
million(Yen)
million(F$)
A. ELIGIBLE PORTIONⅠ) Procurement / Construction 6,778 134 14,074 258
Package 1 River Widening, Rebuilding of Bridge 4,213 77 8,432 155
Package 2 Retarding Basin 1,281 19 2,299 42
Package 3 Ring Dike 40 1 76 1
Package 4 Surrounding Dike 392 5 657 12
Base cost for JICA financing 5,926 102 11,464 210
Price escalation 529 26 1,940 36
Physical contingency 323 6 670 12
Ⅱ) Consulting services 933 18 1,893 35
Base cost 828 14 1,579 29
Price escalation 60 3 223 4
Physical contingency 44 1 90 2
Total (Ⅰ+Ⅱ) 7,711 151 15,967 293
B. NON ELIGIBLE PORTIONa Procurement / Construction 0 0 0 0
Base cost for JICA financing 0 0 0 0
Price escalation 0 0 0 0
Physical contingency 0 0 0 0
b Land Acquisition 0 38 2,093 38
Base cost 0 34 1,845 34
Price escalation 0 3 148 3
Physical contingency 0 2 100 2
c Administration cost 0 17 903 17
d VAT 0 30 1,625 30
e Import Tax 0 0 0 0
Total (a+b+c+d+e) 0 85 4,621 85
TOTAL (A+B) 7,711 236 20,588 3780
C. Interest during Construction 351 0 351 6
Interest during Construction(Const.) 350 0 350 6
Interest during Construction (Consul.) 1 0 1 0
D. Front End Fee 32 0 32 1
GRAND TOTAL (A+B+C+D) 8,094 236 20,971 385
E. JICA finance portion (A) 7,711 151 15,967 293
TotalItem
Total
US$1=2.17 F$, 1F$= JPY 54.5
略 語
ADB Asian Development Bank アジア開発銀行
ADRA Adventist Development and Relief Agency アドベンチスト開発救助機関
AusAID Australian Agency for International Development オーストラリア国際開発庁
BCP Business Continuity Plan 事業継続計画
BOM Bureau Of Meteorology オーストラリア気象局
CBD Convention on Biological Diversity 生物多様性条約
CCA Climate Change Adaptation 気候変動適応
CCL Climate Change Loan 気候変動対策円借款
CCM Climate Change Mitigation 気候変動緩和
CHARM Comprehensive Hazard And Risk Management 統合的ハザード・リスク管理
C/P Counterpart カウンターパート
CRED Centre for the Research on the Epidemiology of Disaster 災害の疫学に関する研究センター
CWO Commissioner Western Office 西部地域長官室
DEM Digital Elevation Model デジタル標高モデル
DF/R Draft Final Report ドラフトファイナルレポート
DIS Drainage & Irrigation Section 排水・灌漑部門
DISMAC Disaster Management Centre 災害管理センター
DMP Disaster Management Plan 防災計画書
DOE Department of Environment 環境局
DOFi Department of Fishery 漁業局
DOF0 Department of Forest 森林局
DOL Department of Lands 土地局
DO-N / DO District Nadi Office / District Office ナンディ地区事務所/地区事務所
DOW Department of Works 公共事業局
DRCC Disaster Ready Community Committee 災害自立型コミュニティ委員会
DRR Disaster Risk Reduction 災害リスク軽減
DRRDM Disaster Risk Reduction & Disaster Management 災害リスク軽減・災害管理
DTCP Department of Town & Country Planning 都市/地方計画局
EDF European Development Fund ヨーロッパ開発基金
EIA Environmental Impact Assessment 環境影響評価
EiE Education in Emergencies 緊急時の教育
EOC Emergency Operation Center 緊急対策室
EPGA Environmental Programme Grant Aids 環境プログラム無償資金協力
EU European Union 欧州連合
EWS Early Warning System 早期警報システム
FBS Fiji Bureau of Statistics フィジー統計局
FMS Fiji Meteorological Service フィジー気象局
F/R Final Report ファイナルレポート
FRA Fiji Road Authority フィジー道路公社
F/S Feasibility Study フィジビリティ調査
FSC Fiji Sugar Corporation フィジー砂糖会社
GDP Gross National Product 国民総生産
GEF Global Environmental Facility 地球環境ファシリティ
GGP Grant Assistance for Grassroots Human Security Projects 草根の無償/草の根・人間の安全保障
無償資金協力
GIS Geographical Information System 地理情報システム
GNI Gross National Income 国民総所得
HFA Hyogo Framework for Action 兵庫行動枠組み
IC/R Inception Report インセプションレポート
IDA Initial Damage Assessment 初期損害評価
IDD Irrigation & Drainage Division 灌漑・排水部門
IDM Introduction of Disaster Management 災害管理の導入
IEE Initial Environmental Examination 初期環境調査
IRC International Red Cross 国際赤十字
IT/R Interim Report インテリムレポート
IWRM Integrated Water Resource Management 統合水資源管理
JCC Joint Coordination Committee 合同調整委員会
JICA Japan International Cooperation Agency 独立行政法人 国際協力機構
KP Kyoto Protocol 京都議定書
LRPD Department of Land Resource Planning & Development 土地資源計画・開発局
LWRM Land &Water Resource Management 土地水資源管理部
MDGs Millennium Development Goals ミレニアム開発目標
MFA&IC Ministry of Foreign Affairs & International Co-operation 外務・国際協力省
MFSPNDS Ministry of Finance Strategic Planning, National Development & Statistics 財務戦略計画・国家開発・統計省
MLGUDHE Ministry of Local Government, Urban Development, Housing &Environment
地方行政・都市開発・住宅・環境省
MLMR Ministry of Lands & Mineral Resources 土地鉱物資源省
M/M Minutes of Meeting 会議議事録
MOA Ministry of Agriculture 農業省
MOU Memorandum Of Understanding 覚書
M/P Master Plan 基本計画
MP Radar Multi Parameter Radar マルチパラメータ気象レーダ
MRMSNDM Ministry of Rural & Maritime Safety & National Disaster Management 地域・海上保安・国家災害管理省
MTCP Ministry of Town and Country Planning 都市計画省
MWTPU Ministry of Works, Transport & Public Utilities 公共事業・運輸・公益事業省
NBCC Nadi Basin Catchment Committee ナンディ流域委員会
NCCP National Climate Change Policy 国家気候変動政策
NDMC National Disaster Management Council 国家災害管理評議会
NDMO National Disaster Management Office 国家災害管理室
NEOC National Emergency Operation Centre 国家緊急オペレーション・センター
NIWA The National Institute of Water and Atmospheric Research 水・大気研究国立機関
NTC Nadi Town Council ナンディ町議会
NZAID New Zealand Agency for International Development ニュージーランド国際開発庁
O&M Operation and Maintenance 運用維持管理
OCHA Office for the Coordination of Humanitarian Affairs 国連人道問題調整事務所
ODA Official Development Assistance 政府開発援助
OJT On the Job Training 実地訓練
PCIDRR The Pacific Community-focused Integrated Disaster Risk
Reduction
大洋州コミュニティ統合的災害リスク削
減
PDM Project Design Matrix プロジェクトデザインマトリックス
PDN Pacific Disaster Net 大洋州災害ネット
PDRMP Pacific Disaster Risk Management (Training) Programme 大洋州災害リスク管理(研修)プログラム
PDRMPN Pacific Disaster Risk Management Partnership Network 大洋州災害リスク管理パートナーシップ・ネットワーク
PHT The Pacific Humanitarian Team 大洋州人道チーム
PIFACC Pacific Islands Framework for Action on Climate Change 大洋州気候変動行動枠組み
PMO Prime Minister Office 首相府
PMU Project Management Unit プロジェクト・マネジメント・ユニット
P/R Progress Report プログレスレポート
PRMS Planning & Resource Management Section 計画・資源管理部門
PRSP Poverty Reduction Strategy Paper 貧困削減戦略文書
PWD Public Works Division 公共事業部
RAP Resettlement Action Plan 住民移転計画
R/D Record of Discussion 討論議事録
RES River Engineering Section 河川エンジニアリング部門
SOP Standard Operation Procedure 標準作業手順書
SOPAC South Pacific Applied Geoscience Commission 太平洋諸島応用科学委員会
SPC Secretariat for the Pacific Community 太平洋コミュニティ事務局
SPCZ South Pacific Convergence Zone 南太平洋収束帯
SPREP South Pacific Regional Environment Programme 大洋州環境プログラム事務局
TC Tropical Cyclone 熱帯性サイクロン
TLTB iTauke Land Trust Board イ・タウケイ土地信託委員会
ToT Training of Trainers 指導員研修
UNCCD United Nations Convention to Combat Desertification 国連砂漠化防止条約
UNDP United Nations Development Programme 国連開発計画
UNESCAP United Nations Economic & Social Commission for Asia & the Pacific
国連アジア太平洋経済社会委員会
UNFCCC United Nations Framework Convention on Climate Change 国連気候変動枠組条約
UNICEF United Nations International Children's Emergency Fund 国連国際児童緊急基金
UNISDR United Nations International Strategy for Disaster 国連国際防災戦略
Reduction
UNOCHA United Nations Office for Coordination of Humanitarian Affairs 国連人道問題支援室
USAID United State Agency for International Development 米国国際開発庁
WAF Water Authority of Fiji フィジー水公社
WB World Bank 世界銀行(世銀)
WMO World Meteorological Organization 世界気象機関
WMS Watershed Management Section 流域管理部門
The Project for the Planning of the Nadi River Flood Control Structures in the Republic of Fiji
YACHIYO ENGINEERING CO.,LTD./CTI ENGINEERING INTERNATIONAL CO.,LTD. JV
Final Report, Volume II Main Report, Part II: Feasibility Study
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THE REPUBLIC OF FIJI THE PROJECT FOR THE PLANNING OF
THE NADI RIVER FLOOD CONTROL STRUCTURES
FINAL REPORT VOLUME II MAIN REPORT
Part II: Feasibility Study
Table of Contents
Map of Project Area
Photo
Executive Summary of Flood Control Master Plan and Priority Project in Nadi River Basin
Abbreviation
Chapter 17 Components of Feasibility Study .................................................................................... 17-1
Chapter 18 Preliminary Design ........................................................................................................... 18-1
18.1 River Widening ...................................................................................................................... 18-1
18.1.1 Applicable standards for design ......................................................................................... 18-1
18.1.2 Plan and Area ..................................................................................................................... 18-1
18.1.3 Longitudinal Plan ............................................................................................................... 18-7
18.1.4 Cross-Sectional Plan ........................................................................................................ 18-10
18.2 Retarding Basin A, B ........................................................................................................... 18-15
18.2.1 Retarding Basin A ............................................................................................................ 18-15
18.2.2 Retarding Basin B ............................................................................................................ 18-21
18.3 Surrounding Dike of Nadi Town .......................................................................................... 18-26
18.4 Ring Dike ............................................................................................................................. 18-29
18.5 Shortcuts of tributaries ......................................................................................................... 18-31
18.6 Rebuilding of Bridges .......................................................................................................... 18-33
18.6.1 Basic Condition for Bridge Design .................................................................................. 18-33
18.6.2 Preliminary Design of Nadi Town Bridge ........................................................................ 18-46
18.6.3 Preliminary Design of Old Queens Road Bridge ............................................................. 18-54
18.7 Approximate Construction Quantity .................................................................................... 18-64
18.7.1 Approximate Construction Quantity ................................................................................ 18-64
18.7.2 Land Acquisition and Compensation ............................................................................... 18-66
18.8 Construction Planning .......................................................................................................... 18-66
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18.8.1 River Works ..................................................................................................................... 18-67
18.8.2 Bridge Works ................................................................................................................... 18-88
18.8.3 Whole Construction Work Schedule .............................................................................. 18-118
Chapter 19 Project Cost Estimation ................................................................................................... 19-1
19.1 Project Cost Estimation System ............................................................................................. 19-1
19.2 Project Cost Unit Price Estimation ......................................................................................... 19-3
19.3 Quantity of Each Work Item .................................................................................................. 19-7
19.4 Project Cost Estimation .......................................................................................................... 19-9
Chapter 20 Project Implementation Plan........................................................................................... 20-1
20.1 Purpose of the Project ............................................................................................................ 20-1
20.2 Target Area ............................................................................................................................. 20-1
20.3 Project Overview .................................................................................................................... 20-1
20.3.1 Overview of the Overall Project Plan ................................................................................. 20-1
20.3.2 Contents of Construction Works ........................................................................................ 20-1
20.3.3 Contents of Consulting Services ........................................................................................ 20-3
20.4 Project Cost and Financial Planning ...................................................................................... 20-4
20.4.1 Calculation of Project Cost ................................................................................................. 20-4
20.4.2 Financial Plan ..................................................................................................................... 20-6
20.5 Project Implementing Schedule .............................................................................................. 20-8
20.6 Procurement Method ............................................................................................................ 20-10
20.6.1 Procurement of Consultants ............................................................................................. 20-10
20.6.2 Procurement of Contractors .............................................................................................. 20-10
20.7 Project Implementing Structure............................................................................................ 20-11
20.7.1 Borrower........................................................................................................................... 20-11
20.7.2 Project Implementing Organization ................................................................................. 20-11
20.7.3 Project Management Unit (PMU) .................................................................................... 20-12
20.8 Operation and Maintenance System ..................................................................................... 20-12
20.9 Performance Indicator .......................................................................................................... 20-13
Chapter 21 Economic Feasibility of the Project ................................................................................ 21-1
21.1 Purpose of economic evaluation .................................................................................................... 21-1
21.2 Preconditions ................................................................................................................................. 21-1
21.2.1 Evaluation Period ................................................................................................................ 21-1
21.2.2 Price level, price escalation ................................................................................................. 21-1
21.2.3 Economic Price ................................................................................................................... 21-2
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21.2.4 Social Discount Rate (SDR) ................................................................................................ 21-2
21.3 Project Cost .................................................................................................................................... 21-2
21.4 Benefits .......................................................................................................................................... 21-2
21.4.1 Method for calculating benefits ........................................................................................... 21-2
21.4.2 Asset data gathering and organizing ................................................................................... 21-3
21.5 Damage and loss calculation ......................................................................................................... 21-6
21.5.1 Method of damage and loss calculation .............................................................................. 21-6
21.5.2 Damage ............................................................................................................................... 21-9
21.5.3 Loss ................................................................................................................................... 21-11
21.6 Economic evaluation ................................................................................................................... 21-18
21.7 Sensitivity analysis ...................................................................................................................... 21-21
21.7.1 Purpose of sensitivity analysis .......................................................................................... 21-21
21.7.2 Considerations for sensitivity analysis .............................................................................. 21-21
21.7.3 Result of sensitivity analysis ............................................................................................. 21-21
Chapter 22 Environmental and Social Considerations ..................................................................... 22-1
22.1 Project Descriptions ............................................................................................................... 22-1
22.1.1 Project Area ........................................................................................................................ 22-1
22.1.2 Project Components ........................................................................................................... 22-1
22.1.3 Outline of Flood Control Measures (Structural Measures) ............................................. 22-1
22.1.4 Outline of Flood Control Measures (Non-Structural Measures) .................................... 22-2
22.1.5 Examination of Alternatives ............................................................................................... 22-2
22.1.6 Construction Plan and Schedule ......................................................................................... 22-6
22.2 Survey Results on Environmental and Social Considerations ................................................ 22-8
22.2.1 Air quality .......................................................................................................................... 22-8
22.2.2 Water Pollution ................................................................................................................ 22-10
22.2.3 Wastes (including excavated materials) ........................................................................... 22-12
22.2.4 Soil Contamination (Riverbed materials) ......................................................................... 22-13
22.2.5 Noise and Vibration ......................................................................................................... 22-15
22.2.6 Offensive Odor ................................................................................................................. 22-17
22.2.7 Hydrological Situation (River flow) ................................................................................. 22-17
22.2.8 Fresh Water Ecology ........................................................................................................ 22-19
22.2.9 Land Area Ecology and Vegetation ................................................................................. 22-21
22.2.10 Ecosystem......................................................................................................................... 22-26
22.2.11 Topography ...................................................................................................................... 22-26
22.2.12 Involuntary Resettlement ................................................................................................. 22-27
22.2.13 Poverty Group .................................................................................................................. 22-31
22.2.14 Indigenous groups ............................................................................................................ 22-32
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22.2.15 Local Economy such as Employment and Livelihood ..................................................... 22-32
22.2.16 Land Use and Utilization of Local Resources .................................................................. 22-33
22.2.17 Water Utilization .............................................................................................................. 22-33
22.2.18 Existing Social Infrastructures and Services .................................................................... 22-34
22.2.19 Misdistribution of Benefits and Damage .......................................................................... 22-35
22.2.20 Cultural Heritage .............................................................................................................. 22-35
22.2.21 Landscape ......................................................................................................................... 22-36
22.2.22 Infectious Diseases such as HIV/AIDS ............................................................................ 22-36
22.2.23 Labor Environment (Including Occupational Safety) / Accident ..................................... 22-37
22.3 Impact Assessment ............................................................................................................... 22-38
22.3.1 Comparison of Scoping and Impact Assessment based on Survey Results ..................... 22-38
22.3.2 Conclusion of Environmental Impact Assessment ........................................................... 22-45
22.4 Environmental Management Plan ........................................................................................ 22-46
22.4.1 Environmental Management Plan during Construction ................................................... 22-46
22.4.2 Environmental Management Plan during Operation ........................................................ 22-50
22.4.3 Organization Chart for Environmental Management and Monitoring ............................. 22-54
22.5 Environmental Monitoring Plan ........................................................................................... 22-56
22.5.1 Environmental Monitoring Plan on Pollution .................................................................. 22-56
22.5.2 Environmental Monitoring Plan on Natural Environment ............................................... 22-59
22.5.3 Environmental Monitoring Plan on Social Environment ................................................. 22-60
22.6 Abbreviated Resettlement Action Plan ................................................................................ 22-62
22.6.1 Project Components ......................................................................................................... 22-62
22.6.2 Objectives of Abbreviated Resettlement Action Plan ...................................................... 22-62
22.6.3 Regal Framework for Land Acquisition and Resettlement .............................................. 22-62
22.6.4 Gaps between JICA Guideline and Fiji’s legal Frameworks............................................ 22-63
22.6.5 Scope of Resettlement Impact .......................................................................................... 22-67
22.6.6 Entitlement Matrix ........................................................................................................... 22-69
22.6.7 Responsible Institutions of Land Acquisition and Resettlement ...................................... 22-70
22.6.8 Land Acquisition and Resettlement Procedures ............................................................... 22-70
22.6.9 Implementation Organization ........................................................................................... 22-71
22.6.10 Responsible Institutions and Mechanism of Grievance Redress ...................................... 22-72
22.6.11 Resettlement Implementation Schedule ........................................................................... 22-72
22.6.12 Cost and Fund Source of Land Acquisition and Resettlement ......................................... 22-73
22.6.13 Monitoring Framework by Implementation Institutions .................................................. 22-75
22.7 Public Consultations and Stake Holders Meetings ............................................................... 22-76
22.7.1 Outline .............................................................................................................................. 22-76
22.7.2 Participants and major opinions ....................................................................................... 22-76
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Chapter 23 Project Evaluation and Recommendations .................................................................... 23-1
23.1 Project Evaluation g ............................................................................................................... 23-1
23.1.1 Economic Valuation ........................................................................................................... 23-1
23.1.2 Financial Valuation ............................................................................................................ 23-1
23.1.3 Environmental Impact Evaluation ...................................................................................... 23-1
23.2 Recommendations for the Implementation of the Project ...................................................... 23-2
23.2.1 Recommendations for the Implementation of the project ................................................... 23-2
23.2.2 Recommendations for Inland water Drainage ..................................................................... 23-3
23.2.3 Recommendations for Mitigation and Management of Disaster Risk ................................ 23-4
Chapter 24 Phasing of the Priority Project (Study for Reference) .................................................. 24-1
24.1 Basic Concept of Phasing ....................................................................................................... 24-1
24.2 Phasing ................................................................................................................................... 24-1
24.2.1 Phasing Case ...................................................................................................................... 24-1
24.2.2 Effectiveness of Phasing(Flood Analysis Result) ......................................................... 24-2
24.2.3 Project Cost of Phasing Project ........................................................................................ 24-12
24.2.4 Benefit of Phasing Project ................................................................................................ 24-12
24.2.5 Economic Evaluation after Phasing .................................................................................. 24-13
24.3 Summary .............................................................................................................................. 24-13
List of Table
Table 17 1 Components of the Feasibility Study .............................................................................................................. 17-1
Table 18 1 Longitudinal Feature (Nadi River) .................................................................................................................... 18-9
Table 18 2 Design Embankment Free-Board .................................................................................................................... 18-10
Table 18 3 Top of Bank Width.......................................................................................................................................... 18-11
Table 18 4 Inspection Passage .......................................................................................................................................... 18-11
Table 18 5 Flood Flow velocity ........................................................................................................................................ 18-14
Table 18 6 Specifications for Retarding Basin A at the Priority Project ........................................................................... 18-15
Table 18 7 Specifications for Retarding Basin B at the Priority Project ........................................................................... 18-21
Table 18 8 Longitudinal Plan of Surrounding Dike of Nadi Town ................................................................................... 18-27
Table 18 9 Major Technical Standards and Reference Documents ................................................................................... 18-33
Table 18 10 Minimum Curve Radius ................................................................................................................................ 18-35
Table 18 11 River Condition (Nadi Town Bridge) ............................................................................................................ 18-41
Table 18 12 River Condition (Old Queens Road Bridge) ................................................................................................. 18-42
Table 18 13 Load Combination for Serviceability Limit State ......................................................................................... 18-45
Table 18 14 Load Combination for Ultimate Limit State .................................................................................................. 18-45
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Table 18 15 Draft Comparison of Bridge Type(Nadi Town Bridge) ........................................................................... 18-50
Table 18 16 Comparison & Selection of Bridge Type(Nadi Town Bridge) ................................................................. 18-51
Table 18 17 Abutment Types and Standard Heights ......................................................................................................... 18-52
Table 18 18 Selection of Foundation Type(Nadi Town Bridge) .................................................................................. 18-53
Table 18 19 Comparison of Bridge Type (Old Queens Road Bridge -Road Bridge-) ....................................................... 18-59
Table 18 20 Comparison & Selection of Bridge Type(Old Queens Road Bridge -Road Bridge-) ............................... 18-60
Table 18 21 Comparison of Bridge Type (Old Queens Road Bridge -Tramline Bridge-) ................................................. 18-60
Table 18 22 Comparison & Selection of Bridge Type(Old Queens Road Bridge -Tramline Bridge-) ......................... 18-61
Table 18 23 Abutment Types and Standard Heights ......................................................................................................... 18-62
Table 18 24 Selection of Foundation Type(Old Queens Road Bridge) ........................................................................ 18-63
Table 18 25 Approximate Construction Quantity (River Works) ..................................................................................... 18-64
Table 18 26 Approximate Construction Quantity (Bridge Works) ................................................................................... 18-65
Table 18 27 Land Acquisition Area .................................................................................................................................. 18-66
Table 18 28 Number of house relocations and affected houses......................................................................................... 18-66
Table 18 29 Main works of river works of the Priority Project ......................................................................................... 18-67
Table 18 30 Division of Construction Section .................................................................................................................. 18-68
Table 18 31 Typical specifications and work quantity of temporary cofferdam ............................................................... 18-76
Table 18 32 Comparison of Mean High Water Spring and Maximum Water Level in Non-flood Season ....................... 18-76
Table 18 33 Acceptable total volume of disposal soil (Rough Estimation) ....................................................................... 18-78
Table 18 34 Suspended days (ratio) by rainfall ................................................................................................................. 18-81
Table 18 35 Calculation of increase coefficient of workable days .................................................................................... 18-81
Table 18 36 Selected Heavy Equipment ........................................................................................................................... 18-82
Table 18 37 Construction Period (River Work) ................................................................................................................ 18-83
Table 18 38 Work Schedule(River Work) ................................................................................................................... 18-84
Table 18 39 Disposal Sites ................................................................................................................................................ 18-85
Table 18 40 Number of Transportation Days and Dump Trucks for Disposal .................................................................. 18-87
Table 18 41 Structural Dimension of Existing Bridge(Nadi Town Bridge) ................................................................. 18-94
Table 18 42 Plan of new Substructure and Foundation (Nadi Town Bridge) .................................................................... 18-97
Table 18 43 Superstructure Reconstruction Plan (Nadi Town Bridge) ............................................................................. 18-99
Table 18 44 Process Scheduling (Nadi Town Bridge) .................................................................................................... 18-102
Table 18 45 Structural Dimension of Existing Bridge (Old Queens Road Bridge) ......................................................... 18-108
Table 18 46 Estimation of Water Level and Discharge in Non-flood Season in Diversion Work .................................. 18-112
Table 18 47 Plan of new Substructure and Foundation (Old Queens Road Bridge) ....................................................... 18-113
Table 18 48 Superstructure Reconstruction Plan (Old Queens Road Bridge) ................................................................. 18-116
Table 18 49 Process Scheduling (Old Queens Road Bridge) .......................................................................................... 18-118
Table 18 50 Whole Construction Work Schedule ........................................................................................................... 18-119
Table 19-1 Ratio of foreign currency (FC) and local currency (LC) of unit prices ............................................................. 19-3
Table 19-2 Unit Prices for river work project cost estimation ............................................................................................ 19-4
Table 19-3 Unit Prices for bridge work project cost estimation (1) .................................................................................... 19-5
Table 19-4 Unit Prices for Bridge work project cost estimation (2) .................................................................................... 19-6
Table 19-5 Cost for Consulting Service .............................................................................................................................. 19-7
Table 19-6 Quantity of Each Work Item of River Improvement......................................................................................... 19-7
Table 19-7 Quantity of Each Work Item of Bridge work .................................................................................................... 19-8
Table 19-8 Quantity of Each Work Item of Site acquisition ............................................................................................... 19-9
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Table 19-9 Number of houses to be affected and relocated by the project .......................................................................... 19-9
Table 19-10 Project Cost ................................................................................................................................................... 19-10
Table 19-11 Base Cost of Each Package ........................................................................................................................... 19-11
Table 19-12 Construction Cost (Package-1: River Widening) .......................................................................................... 19-11
Table 19-13 Construction Cost (Package-1: Rebuilding of Bridges) ................................................................................ 19-12
Table 19-14 Construction Cost (Package-2: Retarding Basin A,B) .................................................................................. 19-13
Table 19-15 Construction Cost (Package-3: Ring Dike) ................................................................................................... 19-13
Table 19-16 Construction Cost (Package-4: Surrounding Dike) ....................................................................................... 19-13
Table 19-17 Construction Cost (Package-4: Shortcut of Tributaries) ............................................................................... 19-14
Table 19-18 Land Acquisition Cost .................................................................................................................................. 19-14
Table 19-19 House Compensation Cost ............................................................................................................................ 19-14
Table 20-1 Summary of Structure Measures in the Priority Project .................................................................................... 20-3
Table 20-2 Outline of the Consulting Service Team ........................................................................................................... 20-3
Table 20-3 Total Cost of the Project ................................................................................................................................... 20-5
Table 20-4 Financial Plan of the Project ............................................................................................................................. 20-6
Table 20-5 Annual Fund Requirements and Breakdown (M JPY (& Million F$)) ............................................................. 20-6
Table 20-6 Breakdown of Annual Fund Requirements (2015-2025, FC: M JPY, LC: M FJD) .......................................... 20-7
Table 20-7 Time Periods Required for Major Processes and their Contents ....................................................................... 20-8
Table 20-8 Implementation Schedule of the Project ........................................................................................................... 20-9
Table 20-9 Procurement Methods for the Main Construction Works of the Project ......................................................... 20-10
Table 20-10 Organization of LWRM in 2015 ................................................................................................................... 20-11
Table 20-11 Operation and Effect Indicators of the Project .............................................................................................. 20-13
Table 21 1 Total appraised value and number of houses in Viti Levu Island in Fiji ........................................................... 21-3
Table 21 2 Average house price in expected inundation area in Viti Levu Island .............................................................. 21-3
Table 21 3 Appraised value of household goods(including passenger car) ................................................................... 21-4
Table 21 4 Average appraised value of household goods(including passenger car) ...................................................... 21-4
Table 21 5 Depreciable property and stocks per each worker in expected inundation area ................................................ 21-4
Table 21 6 Planting acreage, yield and gate price of major crops in expected inundation area ........................................... 21-5
Table 21 7 Summary of assets and damage/loss calculation method .................................................................................. 21-7
Table 21 8 Damage Rate by Inundation Depth ................................................................................................................... 21-9
Table 21 9 Damage ratio in each inundation depth ............................................................................................................. 21-9
Table 21 10 Damage Rate by Inundation Depth ............................................................................................................... 21-10
Table 21 11 Damage Rate by Inundation Depth ............................................................................................................... 21-10
Table 21 12 Crops Damage Rate by Inundation Depth ..................................................................................................... 21-10
Table 21 13 Damage of livestock in the expected inundation area (1/50 probability) ...................................................... 21-11
Table 21 14 Damage of public utilities and infrastructures(1/50 probability) ................................................................ 21-11
Table 21 15 Loss for business in the expected inundation area (1 / 50 probability, except tourism) ................................ 21-12
Table 21 16 Loss for tourism in the expected inundation area (1 / 50 probability) ........................................................... 21-13
Table 21 17 Loss for tourism in reduction of tourist arrivals (1 / 50 probability) ............................................................. 21-13
Table 21 18 Total loss for tourism .................................................................................................................................... 21-13
Table 21 19 Loss for public utilities and infrastructures (1 / 50 probability) .................................................................... 21-14
Table 21 20 Emergency Cost for household (1 / 50 probability) ...................................................................................... 21-14
Table 21 21 Emergency Cost for business entity in the expected inundated area (1 / 50 probability) .............................. 21-15
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Table 21 22 Items of Damage (Without Project, 1/50 probability)................................................................................. 21-15
Table 21 23 Items of Loss (Without Project, 1/50 probability) ......................................................................................... 21-16
Table 21 24 Comparison between the floods in recent years. ........................................................................................... 21-17
Table 21 25 Expected amount of average annual damage and loss reduction with the priority project ............................ 21-17
Table 21 26 Result of Economic Evaluation ..................................................................................................................... 21-18
Table 21 27 Cash flow with the priority project (JPY, 100 million) ................................................................................. 21-18
Table 21 28 Cases subject to sensitivity analysis .............................................................................................................. 21-21
Table 21 29 Result of sensitivity analysis ......................................................................................................................... 21-21
Table 22 1 The Alternatives in Project Components ........................................................................................................... 22-2
Table 22 2 Main works of river works of the Priority Project ............................................................................................. 22-6
Table 22 3 Result of Impact Assessment for Construction of Central High Speed Railway in Japan (Air Pollution) ........ 22-8
Table 22 4 Standard for Air Quality in Japan ...................................................................................................................... 22-9
Table 22 5 Results of Water Quality Test ......................................................................................................................... 22-11
Table 22 6 Result of Riverbed (General Conditions) ........................................................................................................ 22-14
Table 22 7 Result of Riverbed (heavy metal) .................................................................................................................... 22-14
Table 22 8 Japanese Environment Quality Standard for Background Noise ..................................................................... 22-15
Table 22 9 Physical Condition of Survey Sites ................................................................................................................. 22-19
Table 22 10 Results of Inventory Survey (Benthos) ......................................................................................................... 22-20
Table 22 11 Results of Inventory Survey (Fish)................................................................................................................ 22-20
Table 22 12 Results of Inventory Survey (Plants) ............................................................................................................. 22-22
Table 22 13 Results of Inventory Survey (Insects, Birds and Mammals) ......................................................................... 22-25
Table 22 14 Number of Target Households by Community ............................................................................................. 22-28
Table 22 15 Number of Households for Resettlement by Community.............................................................................. 22-29
Table 22 16 Detail of Resettlement Target Households .................................................................................................... 22-30
Table 22 17 Detail of Households to be Relocated ........................................................................................................... 22-30
Table 22 18 Survey Results on Income of Households around the Project area ............................................................... 22-31
Table 22 19 Survey Results on Type of Livelihood of households near the Project Area ................................................ 22-32
Table 22 20 Survey Results for Energy Use around the Project Area ............................................................................... 22-34
Table 22 21 Schooling Capacity in Relate Education system, .......................................................................................... 22-34
Table 22 22 Comparison of Scoping and Impact Assessment based on Survey Results ................................................... 22-39
Table 22 23 Environmental Management Plan (EMP) during Construction ..................................................................... 22-46
Table 22 24 Environmental Management Plan (EMP) during Operation ......................................................................... 22-50
Table 22 25 Environmental Monitoring Plan on Pollution................................................................................................ 22-56
Table 22 26 Environmental Monitoring Plan on Natural Environment ............................................................................. 22-59
Table 22 27 Environmental Monitoring Plan on Social Environment............................................................................... 22-60
Table 22 28 Gaps between Land Acquisition and Resettlement Laws of Fiji and JICA Guidelines ................................. 22-63
Table 22 29 Total population of the Nadi Town and Rural Areas, 2007 Census .............................................................. 22-67
Table 22 30 Number of Project Affected Units (PAUs) and Affected Persons (APs) ....................................................... 22-67
Table 22 31 Area of Affected Lands ................................................................................................................................. 22-67
Table 22 32 Entitlement Matrix ........................................................................................................................................ 22-69
Table 22 33 Grievance Redress Process ............................................................................................................................ 22-72
Table 22 34 Implementation Schedule .............................................................................................................................. 22-72
Table 22 35 Result of Initial land acquisition cost survey ................................................................................................. 22-74
Table 22 36 Monitoring Indicators .................................................................................................................................... 22-75
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Table 23 1 Contents of the 2000 Nadi Town Drainage Plan ............................................................................................... 23-4
Table 24 1 Phasing Case (Structural Measures) ............................................................................................................... 24-1
Table 24 2 Project Cost of Phasing Case........................................................................................................................... 24-12
Table 24 3 Expected amount of average annual damage reduction ................................................................................... 24-12
Table 24 4 Economic Evaluation after Phasing................................................................................................................. 24-13
Table 24 5 Summary of Phasing ....................................................................................................................................... 24-14
List of Figure
Figure 17 1 Components of the Feasibility Study ............................................................................................................. 17-1
Figure 18 1 Designed Discharge Distribution at the Priority Project .................................................................................. 18-1
Figure 18 2 Basic Concept of river Widening ..................................................................................................................... 18-2
Figure 18 3 Whole Plan of River Widening ........................................................................................................................ 18-3
Figure 18 4 Plan of River Widening (1) .............................................................................................................................. 18-4
Figure 18 5 Plan of River Widening (2) .............................................................................................................................. 18-5
Figure 18 6 Plan of River Widening (3) .............................................................................................................................. 18-6
Figure 18 7 Designed Discharge Distribution at the Priority Project .................................................................................. 18-7
Figure 18 8 Designed Longitudinal Plan ............................................................................................................................. 18-8
Figure 18 9 Typical Cross Section (Nadi River) ............................................................................................................... 18-12
Figure 18 10 Designed Discharge Distribution at the Priority Project .............................................................................. 18-15
Figure 18 11 Layout of Retarding Basin A ....................................................................................................................... 18-16
Figure 18 12 General Plan of Retarding Basin A .............................................................................................................. 18-17
Figure 18 13 Typical Cross Section (Retarding Basin A,B) .............................................................................................. 18-18
Figure 18 14 Typical Cross Section of Overflow Dike for Retarding Basin A ................................................................. 18-19
Figure 18 15 General Plan of Overflow Dike for Retarding Basin A................................................................................ 18-20
Figure 18 16 Layout of Retarding Basin B ....................................................................................................................... 18-22
Figure 18 17 General Plan of Retarding Basin B .............................................................................................................. 18-23
Figure 18 18 Typical Cross Section of Overflow Dike for Retarding Basin B ................................................................. 18-24
Figure 18 19 General Plan of Overflow Dike for Retarding Basin B ................................................................................ 18-25
Figure 18 20 Plan of Surrounding Dike ............................................................................................................................ 18-26
Figure 18 21 Typical Cross Section (Surrounding Dike of Nadi Town) ........................................................................ 18-28
Figure 18 22 Plan of Ring Dike ........................................................................................................................................ 18-29
Figure 18 23 Typical Cross Section (Ring Dike) .............................................................................................................. 18-30
Figure 18 24 Plan of Shortcuts of Tributaries ................................................................................................................... 18-31
Figure 18 25 Typical Cross Section (Shortcuts of Tributaries) ......................................................................................... 18-32
Figure 18 26 Routes as Importance Level 3 .................................................................................................................... 18-34
Figure 18 27 Design Cross Section ................................................................................................................................. 18-35
Figure 18 28 Cross Section of Denarau Bridge ............................................................................................................... 18-36
Figure 18 29 Location of Boring Holes (Nadi Town Bridge) ......................................................................................... 18-39
Figure 18 30 Location of Boring Holes (Old Queens Road Bridge ................................................................................ 18-40
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Figure 18 31 Vehicle Loading ......................................................................................................................................... 18-43
Figure 18 32 Design Live Load (Tramline Bridge) ......................................................................................................... 18-43
Figure 18 33 (1) Bridge Location .................................................................................................................................... 18-46
Figure 18 33 (2) Existing Bridge Side View (Nadi Town Bridge) ................................................................................ 18-46
Figure 18 34 Rebuilt Bridge Side View (Nadi Town Bridge) Source: JICA Study Team .............................................. 18-46
Figure 18 35 Design Plan and Side View (Nadi Town Bridge) ...................................................................................... 18-48
Figure 18 36 The wall type pier ...................................................................................................................................... 18-52
Figure 18 37 (1) Bridge Location .................................................................................................................................... 18-54
Figure 18 37 (2) Side View of Existing Bridge (Old Queens Road Bridge) ................................................................... 18-55
Figure 18 38 Side View of Rebuilt Bridge (Old Queens Road Bridge) .......................................................................... 18-55
Figure 18 39 Plan and Side View (Old Queens Road Bridge) ........................................................................................ 18-57
Figure 18 40 The wall type pier ........................................................................................................................................ 18-62
Figure 18 41 The Components of the Priority Project (Structural Measures) ................................................................... 18-67
Figure 18 42 Division of Construction Section ................................................................................................................. 18-69
Figure 18 43 Construction Step ......................................................................................................................................... 18-70
Figure 18 44 Excavation Method ...................................................................................................................................... 18-72
Figure18 45 Loading and Transportation Method ............................................................................................................. 18-72
Figure 18 46 Embankment Method ................................................................................................................................... 18-73
Figure 18 47 Construction Method for Foundation of Structures...................................................................................... 18-74
Figure 18 48 Construction Method for Concrete Placement ............................................................................................. 18-74
Figure 18 49 Temporary Construction Road ..................................................................................................................... 18-75
Figure 18 50 Temporary Construction Road for River-Crossing ...................................................................................... 18-75
Figure 18 51 Cross Section of Temporary Coffer Dam .................................................................................................... 18-76
Figure 18 52 Proposal Area for disposal sites ................................................................................................................... 18-78
Figure 18 53 Boundary of Nadi Town (Existing and Proposed) ....................................................................................... 18-79
Figure 18 54 Construction Step (1) ................................................................................................................................... 18-80
Figure 18 55 Construction Step (2) ................................................................................................................................... 18-80
Figure 18 56 Routes of Disposal Transportation ............................................................................................................... 18-86
Figure 18 57 Construction Flow(Nadi Town Bridge) .................................................................................................. 18-88
Figure 18 58 Construction Step (Nadi Town Bridge) ....................................................................................................... 18-92
Figure 18 59 (1) Detour Route (Nadi Town Bridge) ......................................................................................................... 18-93
Figure 18 59 (2) Detour Planning (Nadi Town Bridge) .................................................................................................... 18-93
Figure 18 60 General Drawing of Existing Bridge(Nadi Town Bridge) ...................................................................... 18-95
Figure 18 61 Removal Plan of Superstructure (Nadi Town Bridge) ................................................................................. 18-96
Figure 18 62 Access Road Plan (Nadi Town Bridge) ....................................................................................................... 18-97
Figure 18 63 General Drawing of New Bridge (Nadi Town Bridge) ................................................................................ 18-98
Figure 18 64 Example of Pile Construction (Pile driving by Diesel Hammer) ................................................................. 18-99
Figure 18 65 Example of Girder Installation by Erection Beam ..................................................................................... 18-100
Figure 18 66 Example of Supere Structure Election ....................................................................................................... 18-101
Figure 18 67 Construction Flow(Old Queens Road Bridge) ...................................................................................... 18-103
Figure 18 68 Construction Step Flow (Old Queens Road Bridge) .................................................................................. 18-106
Figure 18 69 Detour Route (Old Queens Road Bridge) .................................................................................................. 18-107
Figure 18 70 Detour Planning (Old Queens Road Bridge) .............................................................................................. 18-107
Figure 18 71 General Drawing of Existing Bridge (Old Queens Road Bridge) .............................................................. 18-109
Figure 18 72 Plan for Removal of Superstructure (Old Queens Road Bridge)................................................................ 18-110
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Figure 18 73 Construction Access Road (Old Queens Road Bridge) .............................................................................. 18-113
Figure 18 74 General Drawing of New Bridge (Old Queens Road Bridge -Road Bridge-) ............................................ 18-114
Figure 18 75 General Drawing of New Bridge (Old Queens Road Bridge -Tramline Bridge-) ...................................... 18-115
Figure 18 76 Example of Pile Construction (Pile driving by Diesel Hammer) ............................................................... 18-116
Figure 18 77 Example of Girder Installation by Erection Beam ..................................................................................... 18-117
Figure 20-1 Components of structure measures of the priority project ............................................................................... 20-1
Figure 20-2 Design Flood Discharge of The Priority Project .............................................................................................. 20-2
Figure 20-3 Target Area of Structure Measurement on the Priority Project ........................................................................ 20-2
Figure 20-4 Draft project implementing structure ............................................................................................................. 20-11
Figure 20-5 PMU Organizations and Functions in Execution of Yen Loan and Technical Cooperation Project .............. 20-12
Figure 21 1 Division Map of Planting Acreage of Major Crops ......................................................................................... 21-6
Figure 21 2 Viti-Levu and Yasawa-Mamanuca islands in Fjji .......................................................................................... 21-12
Figure 21 3 Damage and Loss ratio................................................................................................................................... 21-15
Figure 21 4 Ratio of damage by category ......................................................................................................................... 21-16
Figure 21 5 Ratio of loss by category................................................................................................................................ 21-16
Figure 22 1 Nadi River Basin and the Project Area ............................................................................................................ 22-1
Figure 22 2 Proposal Area for disposal sites ....................................................................................................................... 22-7
Figure 22 3 Situation of water sampling (sampling for lab test and in site measurement) ................................................ 22-10
Figure 22 4 Water Sampling Sites along the Nadi River ................................................................................................... 22-10
Figure 22 5 Riverbed Material Sampling Sites along the Nadi River ............................................................................... 22-13
Figure 22 6 Example of samples (Site2) ........................................................................................................................... 22-14
Figure 22 7 Distance Depression level in Noise in Tokyo (Backhoe) ............................................................................... 22-16
Figure 22 8 Distance Depression level in Vibration in Tokyo (Backhoe) ......................................................................... 22-16
Figure 22 9 Condition of Algae in Namosi River which Identified during Water and Riverbed Survey .......................... 22-17
Figure 22 10 Survey Locations for Freshwater Inventory Survey ..................................................................................... 22-19
Figure 22 11 Survey Locations for Land Area Ecological Inventory Survey .................................................................... 22-21
Figure 22 12 The Survey Target of Social Economic Survey ........................................................................................... 22-28
Figure 22 13 The Project Implementation Organization (During Construction) (in case of Japanese Yen Loan) .......... 22-54
Figure 22 14 Area of Affected Lands ................................................................................................................................ 22-68
Figure 22 15 Implementation organization for land acquisition and resettlement ............................................................. 22-71
Figure 23 1 Drainage system of rainfall water in the central area of Nadi town ................................................................. 23-3
Figure 23 2 Nadi Town Drainage Plan (2000) .................................................................................................................... 23-4
Figure 24 1 The components of the Priority Project (Structural Measures) ...................................................................... 24-1
Figure 24 2 Phasing Case of the Priority Project ............................................................................................................... 24-2
Figure 24 3 Summary of Flood Analysis Result after Phasing (Inundation Area, Average Inundation Depth) ................ 24-3
Figure 24 4 Flood Analysis Result (Case0: Current Situation)(1/2) ............................................................................... 24-4
Figure 24 5 Flood Analysis Result (Case0: Current Situation)(2/2) ............................................................................... 24-5
Figure 24 6 Flood Analysis Result (Case1: Retarding Basin A, B)(1/2) ........................................................................ 24-6
Figure 24 7 Flood Analysis Result (Case1: Retarding Basin A, B)(2/2) ........................................................................ 24-7
Figure 24 8 Flood Analysis Result (Case2: River Widening L=13km form 5.75 to 18.75km)(1/2) ............................... 24-8
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Figure 24 9 Flood Analysis Result (Case2: River Widening L=13km form 5.75 to 18.75km)(2/2) ............................... 24-9
Figure 24 10 Flood Analysis Result (Case3: River Widening L=8.25km form 5.75 to 14.0km)(1/2) ............................ 24-10
Figure 24 11 Flood Analysis Result (Case3: River Widening L=8.25km form 5.75 to 14.0km)(2/2) ............................ 24-11
Figure 24 12 Flood Analysis Result by Full Components of the Priority Project ............................................................. 24-14
Figure 24 13 Flood Analysis Result by Case2: River Widening L=13km form 5.75 to 18.75km ..................................... 24-15
Figure 24 14 Flood Analysis Result by River Widening L=8.25km form 5.75 to 14.0km................................................ 24-15
Appendix
Appendix-1 Flowchart of the Study ............................................................................................... A1-1
Appendix-2 Plan of Expert Assignment ......................................................................................... A2-1
Appendix-3 TOR of JCC and JCC Member List ......................................................................... A3-1
Appendix-4 TOR of TWG and Member List ................................................................................. A4-1
Appendix-5 MM of JCC .............................................................................................................. A5-1
Appendix-6 MM of TWG ............................................................................................................ A6-1
Appendix-7 MM of Meeting with MOA ........................................................................................ A7-1
Appendix-8 Drawings .................................................................................................................... A8-1
Appendix-9 Documents for cost estimation of land acquisition (MOL) ........................................ A9-1
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Chapter 17 Components of Feasibility Study
The components of FS study are as shown in Table 17-1 and Figure 17-1.
The purpose of the Priority Project is to prevent inundation in Important Protected Area which is located
along the Nadi River (see area which is surrounded by yellow line in Figure 17-1 )
Table 17-1 Components of the Feasibility Study
Quantities
1. Nadi River Downstream (1) Retarding Basin and River
Improvement in downstream - -
(2) Ring Dike ④ Ring Dike L=1.8 km -Middlestream (3) River Widening
2) ① River Widening
Rebuilding of Nadi TOwn Bridge
Rebuilding of Old Queens Road Bridge
L=13 km
L=108 m
L= 96 m
(4) Retarding Basin A ② Retarding Basin A A=35 ha
V=795 千m3
Retarding Basin B ② Retarding Basin B A=178 ha
V=6,920 千m3
Upstream (5) Dam and River improvement in
upstream -
2. Tributaries (6) River Improvement ⑤③-2
Shortsut of Tributaries
Surrounding Dike of Nadi Town
L=0.5 km
L=4.5 km
Retarding Basins (13 sites)-
Shortcut and Surrounding dike in
tributaries are preceded to
construction as part of the master
plan―
Component of the Priority ProjectRemarks
Main Component
Structural
Measures ―
-
-
―
Nawaka
Maralua
Namosi
River
River, LocationComponent of
the Master Plan
S
Malakua River
⑥Rebuilding of Bridge ①River Widening: L=13km
① River Widening
② Retarding Basin A, B
③ Surrounding Dike
④ Ring Dike
⑤ Shortcut of tributaries
⑥ Rebuilding of Bridge (Nadi town bridge)
⑦ Rebuilding of Bridge (Old Queens Road bridge)
Component
②Retarding Basin A: A=35haRetarding Basin B: A=178ha
(Water Surface Area in flooding)
⑥Rebuilding of Bridge: L=108m
⑦Rebuilding of Bridge: L=96m
③Surrounding Dike: L=4.5km
④Ring Dike: L=1.8km
⑤Shortcuts: L=0.5km
Figure 17-1 Components of the Feasibility Study
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Chapter 18 Preliminary Design
18.1 River Widening
This project (the Priority Project) is intended to implement the river improvement project to prevent
flooding in the Important Protected Area which is located in the Nadi River Basin. the components of the
Priority Project are as described before in Chapter 18.
River Widening is intended to flow down 1,800 m3/s flood discharge which is equal to the design flood
with occurrence probability of 1/50 with the water level1 between the top of dike and HWL at the Back
Road Bridge point in the middle section
No.25 2012年3月洪水
NawakaRiver NamosiRiver
[3,650]
1,000
[900]
900
[1,450]
1,000
NadiRiverNaditownBridge BackroadBridge
[2,450]
1,400
[2,450]
1,400
[2,450]
1,600[1,750]
830
Votualevu
[上段]:基本高水
下段:整備後流量(MP)
[3,650]
2,400
B
A
-200
-40
V=6,520千m3
V=640千m3
-1400
NawakaRiver NamosiRiver
[3,650]
1,000
[900]
730
[1,450]
1,130
NadiRiverNaditownBridge BackroadBridge
[2,450]
1,800
[2,450]
1,800
[2,450]
2,450[1,750]
1,740
Votualevu
[上段]:基本高水
下段:整備後流量(優先プロジェクト)
[3,650]
2,950
B
A
-510
-80
V=7,200千m3
V=1,000千m3
NawakaRiver
[Upper]: Discharge before Flood Control
[Lower]: Design Discharge after the Priority Project
V=7,200 thousand m3
V=1,000 thousand m3
Figure 18-1 Designed Discharge Distribution at the Priority Project
18.1.1 Applicable standards for design
There are no Fiji own technical standards and guidelines for flood control and river facilities. Therefore, it
is required to refer to some sort of technical standards and guidelines for design.
In this situation, comparing river characteristics in Japan and those in Fiji, flood characteristics and river
characteristics of river basins in Japan and that of Nadi River basin in Fiji are to be similar considering that
there are mountains in upstream basin, water flows from upstream and flows out to sea through low-lying
areas in a short time. In addition, Natural science and technology and a variety of engineering required to
design (hydraulics, physics, soil, geotechnical engineering, river engineering, concrete engineering, etc.), is
considered one of the universal that does not depend on the countries and regions. Therefore, in this design,
it is considered to be applicable to refer the Japanese of design standards and guidelines1.
Therefore, in this design according to the following river facilities, [Structural Ordinance for river facilities
(1976.7.20)], [Revised Edition, Ministry of Construction, Technical Criteria for River Works, Editorial
Supervisor: River Bureau, Ministry of Construction, Editor: Japan River Association] and are referred.
18.1.2 Plan and Area
(1) Planned Area
River widening is conducted from 5.75k point near Narewa village to 24.0k point near Votualevu village.
This area is determined through flood analysis in order to prevent inundation in the Important Protected
Area. Earth dike is not included in order to mitigate negative impact by the dike of main stream to other
area including tributaries so that only river widening is conducted from 5.75k to 8.0k. Whole plan of river
widening is as described in Figure 18-3.
1 When the Master Plan will be completed, since the upstream dam is constructed, the discharge of 1,800m3/s can flow down in the river channel section with free-board. In the Priority Project the discharge is permitted to flow down with the water level between the top of dike
and HWL considering that this stage is a step to the Master Plan.
2See [Draft Final Report: Main Report, Part I: Master Plan Study, Chapter 4, 4.1.1 ]
※Flow volume after the priority project include natural
flood volume at outside section of Important Protected Area
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(2) Plan Alignment of river widening is set considering current alignment of river channel and flood flow. Width of river widening is set basically same width from center line between right bank side and left bank side from the point of view of fairness.
10.25K
Current Cross SectionCross Section after River Widening
Figure 18-2 Basic Concept of river Widening
Alignment of river channel is sifted or loosed in order not to exceed design flood water revel when flood water level exceeds design high water level due to effect by curvature at current alignment and there are important areas to be protected behind the river. (Exception-1)
Alignment is loosed to the extent that does not deviate from the current river channel alignment extremely for excessive bending portion such as a U-shaped or S-shaped curve (Exception-2) and alignment is newly set for extreme crank shape curve in light of the continuity of the upstream and downstream alignment (Exception-3).
Alignment of river channel is straighten and smoothen from 22.75k to 24.25k in order to intake flood water smoothly to the retarding basin at overflow dike securing a required length and elevation (Exeption-4).
Alignment is sifted to the other side to the extent that there is no hindrance to a safe flow of flood water from the viewpoint of reducing the number of house relocations if houses are present only one side of the river channel (Exception-5)
Based on the above, plan of river widening is as shown in from Figure 18-3 to Figure 18.6.
In Figure 18-4~Figure 18.6 there are two kind of river alignment, blue and yellow lines, the blue line shows the present river alignment and yellow line shows the alignment after river improvement.
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Figure 18-3 Whole Plan of River Widening
Nadi river
River Widening: L=13km
5.75km
18.75km
Back Road Bridge
Narewa village
Denarau
:Embankment
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Figure 18-4 Plan of River Widening (1)
(Edge of the embankment or river inspection passage at landside)
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Figure 18-5 Plan of River Widening (2)
(Edge of the embankment or river inspection passage at landside)
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Figure 18-6 Plan of River Widening (3)
(Edge of the embankment or river inspection passage at landside)
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18.1.3 Longitudinal Plan
(1) Design High Water Level
The design high water level in a section from the lower reaches to the middle reaches is roughly set up to
the inland ground level and which is set up based on the non-uniform flow calculation result at the time of
design flow discharge, and the design high water level it is set up based on the overflow depth of the
retarding basin and the non-uniform flow calculation result at the time of design flow discharge for a
section in the upper reaches. (For more information see Draft Final Report, Main Report I: Master Plan
Study, Chapter 8, 8.2.3 Longitudinal Plan). The High Water Level which is set based on the above is
shown in Figure 18-8.
The High Water Level is set for Master Plan Level, however, after priority project before the
completion of Master Plan, flood water level will exceed the High Water Level (but under designed
dike crown elevation) by target design scales level flood (2012 flood).
Designed Discharge Distribution at the Priority Project is as shown in Figure 18-7.
No.25 2012年3月洪水
NawakaRiver NamosiRiver
[3,650]
1,000
[900]
900
[1,450]
1,000
NadiRiverNaditownBridge BackroadBridge
[2,450]
1,400
[2,450]
1,400
[2,450]
1,600[1,750]
830
Votualevu
[上段]:基本高水
下段:整備後流量(MP)
[3,650]
2,400
B
A
-200
-40
V=6,520千m3
V=640千m3
-1400
NawakaRiver NamosiRiver
[3,650]
1,000
[900]
730
[1,450]
1,130
NadiRiverNaditownBridge BackroadBridge
[2,450]
1,800
[2,450]
1,800
[2,450]
2,450[1,750]
1,740
Votualevu
[上段]:基本高水
下段:整備後流量(優先プロジェクト)
[3,650]
2,950
B
A
-510
-80
V=7,200千m3
V=1,000千m3
NawakaRiver
[Upper]: Discharge before Flood Control
[Lower]: Design Discharge after the Priority Project
V=7,200 thousand m3
V=1,000 thousand m3
Figure 18-7 Designed Discharge Distribution at the Priority Project
※Flow volume after the priority project include natural
flood volume at outside section of Important Protected Area
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Nawaka River
Nadi town Bridge
OldQueensroad Bridge
Back road Bridge
Namosi River
-5.0
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
0.0 5.0 10.0 15.0 20.0 25.0
Ele
vati
on(
m)
km
Design Embankment Height
HWL
Design Riverbed (after improvement)
Right Bank
Left Bank
Average Riverbed
Lowest Riverbed
Calculation Water Level for Design FloodDischarge(Planned River)Left side :Water Level Rising amount due to curvatureConsidered (Planned River)Rignt side :Water Level Rising amount due to curvatureConsidered (Planned River)Calculation Water Level for Design FloodDischarge(Current River)Reference Point
After smoothing :Water Level Rising amount due tocurvature Considered (Planned River)
Gradient of Design Riverbed=1/4,200 Gradient of Design Riverbed=1/2,600 Gradient of Design Riverbed=1/1,350 Gradient of Design Riverbed=1/1,000
Gradient of HWL=1/2,150
Gradient of HWL=1/1,600
Gradient of HWL=1/700
Gradient of HWL=1/2,600
Design Flood Discharge=1,000m3/s
Design Flood Discharge=2,400m3/s
Design Flood Discharge=1,400m3/s
Design Flood Discharge=1,600m3/s Design Flood Discharge=830m3/s
Gradient of HWL=1/1000
Overflow section of Retarding Basin B
Segment3、coefficient roughness for low-water channel n=-0.015
Segment2-2、coefficient roughness for low-water channel n=-0.023Segment2-1、coefficient roughness for low-water channel n=-0.027
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
0.0 5.0 10.0 15.0 20.0 25.0
Velo
city(m
)
km
Flow Velocity at the time of Design Flood Discharge
(current channel:mean cross-section)
Flow Velocity at the time of Design Flood Discharge
(planned channel:average cross-section)
Figure 18-8 Designed Longitudinal Plan
Ground elevation at Right Bank Side
Ground elevation at Left Bank Side
The Project for the Planning of the Nadi River Flood Control Structures in the Republic of Fiji
YACHIYO ENGINEERING CO.,LTD./CTI ENGINEERING INTERNATIONAL CO.,LTD. JV
Final Report, Volume II Main Report, Part II: Feasibility Study
18-9
Table 18-1 Longitudinal Feature (Nadi River)
Structure Interval Left Bank Right BankLowest
Riverbed
Average
Riverbed
Headroom for
bridge girder -
free-board
Calculation
water level of
Design Flood
Water level
rising amount
due to
Water level
after
curvature
HWL - non-
uniform flow
calculation
Flow velocityAllocation of
Flow rateFee-board HWL
Designed
Embankment
Height
Design Riverbed
(after improvement)Design water depthDesign river width
Gradient of
HWL
Lowest Riverbed
(after
improvement)
Calculation Water
Level for Design
Flood Discharge
Water level rising
amount due to
curvature
Water level after
consideration of
curvature
HWL - non-
uniform flow
calculation
Flow velocity
0.000 0.000 0.280 0.270 -4.630 -3.963 1.19 0.00 0.00 1.91 1.0 1.19 2.19 -3.85 5.038 80 1.19 0.00 0.00 1.87
0.250 0.250 1.660 1.860 -4.270 -3.935 0.77 0.00 0.54 3.72 1.0 1.30 2.30 -3.79 5.095 80 0.99 0.00 0.31 2.89
0.500 0.250 1.550 1.700 -3.730 -3.395 0.79 0.00 0.63 4.13 1.0 1.42 2.42 -3.73 5.152 80 1.00 0.00 0.42 3.12
0.750 0.250 1.580 1.540 -3.350 -2.444 1.13 0.12 1.25 0.29 3.85 1.0 1.54 2.54 -3.67 5.208 80 1.16 0.12 1.28 0.26 2.92
1.000 0.250 2.300 1.860 -2.900 -1.994 1.24 0.12 1.37 0.29 4.18 1.0 1.65 2.65 -3.61 5.265 80 1.24 0.12 1.37 0.29 2.92
1.250 0.250 3.330 1.650 -3.642 -3.374 1.91 0.12 2.04 -0.27 2.87 1.0 1.77 2.77 -3.55 5.322 80 1.35 0.12 1.48 0.29 2.81
1.500 0.250 2.000 1.593 -4.356 -4.088 2.19 0.12 2.31 -0.42 2.03 1.0 1.89 2.89 -3.49 5.379 80 1.57 0.12 1.70 0.19 2.19
1.750 0.250 1.410 1.760 -3.420 -2.770 2.05 0.12 2.18 -0.17 2.80 1.0 2.00 3.00 -3.43 5.435 80 1.47 0.12 1.60 0.40 2.79
2.000 0.250 5.736 2.605 -2.950 -2.503 2.10 0.12 2.22 -0.10 2.94 1.0 2.12 3.12 -3.37 5.492 80 1.57 0.12 1.70 0.42 2.69
2.250 0.250 5.960 1.920 -3.354 -2.844 2.34 0.25 2.59 -0.36 2.30 1.0 2.23 3.23 -3.31 5.549 80 1.68 0.25 1.94 0.30 2.53
2.500 0.250 5.800 2.430 -3.710 -3.200 2.37 0.25 2.62 -0.27 2.40 1.0 2.35 3.35 -3.25 5.606 80 1.74 0.25 1.99 0.36 2.55
2.750 0.250 4.910 1.990 -2.730 -2.321 2.55 0.25 2.80 -0.33 1.70 1.0 2.47 3.47 -3.20 5.662 80 1.94 0.25 2.19 0.28 1.86
3.000 0.250 3.170 3.083 -2.040 -1.631 2.42 0.00 0.16 2.52 1.0 2.58 3.58 -3.14 5.719 80 1.89 0.00 0.69 2.28
3.250 0.250 7.200 2.350 -3.126 -2.665 2.52 0.00 0.18 2.38 1.0 2.70 3.70 -3.08 5.776 80 1.87 0.00 0.83 2.58
3.500 0.250 1.950 3.097 -3.560 -3.099 2.65 0.12 2.77 0.04 1.97 1.0 2.82 3.82 -3.02 5.833 80 2.01 0.12 2.13 0.69 2.27
3.750 0.250 3.080 2.440 -2.910 -1.471 2.57 0.12 2.69 0.24 2.54 1.0 2.93 3.93 -2.96 5.889 80 2.02 0.12 2.14 0.80 2.46
4.000 0.250 2.714 2.286 -2.370 -1.636 2.73 0.12 2.85 0.20 2.10 1.0 3.05 4.05 -2.90 5.946 80 2.15 0.12 2.27 0.78 2.12
4.250 0.250 3.200 3.570 -1.900 -1.374 2.80 0.00 0.36 2.28 1.0 3.16 4.16 -2.84 6.003 80 2.28 0.00 0.89 2.17
4.500 0.250 3.800 5.230 -1.770 -1.244 2.99 0.00 0.30 2.29 1.0 3.28 4.28 -2.78 6.060 80 2.53 0.00 0.76 2.10
4.750 0.250 3.520 3.970 -2.800 -2.460 3.32 0.00 0.08 2.06 1.0 3.40 4.40 -2.72 6.116 80 2.76 0.00 0.63 2.17
5.000 0.250 4.460 4.360 -3.610 -2.923 3.66 0.06 3.72 -0.21 1.92 1.0 3.51 4.51 -2.66 6.173 80 2.97 0.06 3.03 0.48 2.23
5.250 0.250 3.750 4.440 -3.490 -2.061 3.83 0.06 3.89 -0.26 1.88 1.0 3.63 4.63 -2.60 6.230 80 3.15 0.06 3.21 0.42 1.94
5.500 0.250 3.714 3.587 -2.640 -1.645 3.93 0.06 3.99 -0.25 2.29 1.0 3.75 4.75 -2.54 6.287 80 3.24 0.06 3.30 0.45 2.15
5.750 0.250 2.850 5.230 -1.390 -0.836 4.28 0.15 4.42 -0.56 1.48 1.0 3.86 4.86 -2.48 6.343 150 3.50 0.15 3.64 0.22 1.19
6.000 0.250 3.910 5.480 -1.440 -1.141 4.06 0.00 -0.08 6.41 1.2 3.98 5.18 -2.42 6.400 150 3.18 0.00 0.80 3.08
6.250 0.250 3.970 3.780 -1.645 -0.936 7.12 0.20 7.31 -3.22 3.12 1.2 4.09 5.29 -2.36 6.457 150 3.37 0.20 3.56 0.53 3.07
6.500 0.250 3.720 4.115 -1.650 -1.116 7.31 0.20 7.51 -3.30 3.74 1.2 4.21 5.41 -2.30 6.514 150 3.57 0.20 3.77 0.45 2.95
6.750 0.250 3.240 6.200 -2.340 -1.339 8.02 0.20 8.21 -3.89 2.89 1.2 4.33 5.53 -2.24 6.570 150 3.73 0.20 3.93 0.40 2.93
7.000 0.250 4.090 3.867 -2.480 -1.479 8.20 0.47 8.68 -4.23 3.39 1.2 4.44 5.64 -2.18 6.627 150 3.94 0.47 4.42 0.03 2.66
7.250 0.250 3.130 4.700 -3.027 -1.045 8.90 0.18 9.08 -4.51 1.64 1.2 4.56 5.76 -2.12 6.684 150 4.07 0.18 4.25 0.31 2.62
7.500 0.250 4.620 3.610 -3.000 -1.332 8.87 0.18 9.05 -4.37 2.44 1.2 4.68 5.88 -2.06 6.741 150 4.18 0.18 4.36 0.32 2.71
7.750 0.250 3.640 5.080 -3.300 -1.919 9.14 0.00 -4.34 1.92 1.2 4.79 5.99 -2.00 6.797 150 4.30 0.00 0.49 2.76
8.000 NavuBridge(支川) 0.250 4.525 2.624 -3.320 -2.117 9.29 0.45 9.75 -4.84 1.64 1.2 4.91 6.11 -1.95 6.854 150 4.45 0.45 4.90 0.01 2.67
8.250 0.250 4.424 5.156 -1.150 0.049 9.32 0.00 -4.29 1.92 1.0 5.03 6.11 -1.89 6.911 100 4.64 0.00 0.38 2.39
8.500 0.250 5.740 6.013 -0.820 -0.356 9.26 0.00 -4.12 2.62 1.0 5.14 6.14 -1.83 6.968 100 4.75 0.00 0.39 2.48
8.750 0.250 5.836 6.480 -1.890 -1.138 9.45 0.26 9.71 -4.45 2.57 1.0 5.26 6.26 -1.77 7.024 100 4.90 0.26 5.15 0.10 2.41
9.000 0.250 4.050 6.150 -1.430 -0.393 9.73 0.26 9.98 -4.61 2.21 1.0 5.37 6.37 -1.71 7.081 100 5.05 0.26 5.30 0.07 2.29
9.250 0.250 5.750 4.220 -0.800 0.202 9.96 0.18 10.14 -4.65 1.76 1.0 5.49 6.49 -1.65 7.138 100 5.17 0.18 5.35 0.14 2.19
9.500 0.250 6.060 6.170 -1.050 -0.600 10.05 0.00 -4.44 1.95 1.0 5.61 6.61 -1.59 7.195 100 5.26 0.00 0.34 2.25
9.750 0.250 6.360 6.290 -2.000 -1.450 10.20 0.00 -4.47 1.79 1.0 5.72 6.72 -1.53 7.251 100 5.36 0.00 0.36 2.27
9.830 NaditownBridge 0.080 6.300 6.300 -4.730 -2.131 5.300 10.29 0.00 -4.53 1.73 1.0 5.76 6.76 -1.51 7.270 100 5.51 0.00 0.25 2.16
10.000 0.170 6.310 7.020 -1.300 -0.398 10.18 0.00 -4.34 2.66 1.0 5.84 6.84 -1.47 7.308 100 5.54 0.00 0.30 2.26
10.250 0.250 6.630 6.460 -0.820 0.028 10.30 0.07 10.36 -4.41 3.51 1.0 5.96 6.96 -1.41 7.365 100 5.65 0.07 5.72 0.24 2.21
10.500 0.250 6.990 7.210 -1.250 -0.431 11.12 0.07 11.19 -5.12 1.66 1.0 6.07 7.07 -1.35 7.422 100 5.76 0.07 5.83 0.25 2.18
10.750 0.250 5.850 6.730 -0.670 -0.376 11.23 0.07 11.30 -5.11 1.56 1.0 6.19 7.19 -1.29 7.478 100 5.85 0.07 5.92 0.27 2.18
11.000 0.250 9.310 6.630 -3.610 -2.289 11.33 0.00 -5.03 1.49 1.0 6.30 7.30 -1.23 7.535 100 5.97 0.00 0.33 1.98
11.250 0.250 17.830 6.950 -1.760 -0.769 11.39 0.16 11.55 -5.13 1.73 1.0 6.42 7.42 -1.17 7.592 100 5.99 0.16 6.16 0.26 2.25
11.500 0.250 5.820 7.090 -1.460 -0.950 11.56 0.16 11.72 -5.18 1.29 1.0 6.54 7.54 -1.11 7.649 100 6.12 0.16 6.28 0.25 2.12
11.750 0.250 6.350 6.900 -0.770 -0.622 11.56 0.00 -4.90 1.90 1.0 6.65 7.65 -1.05 7.705 100 6.19 0.00 0.46 2.23
12.000 0.250 6.720 9.190 -1.080 -0.574 11.70 0.00 -4.93 1.60 1.0 6.77 7.77 -0.99 7.762 100 6.30 0.00 0.47 2.18
12.250 0.250 8.250 6.100 -1.440 -0.750 11.80 0.00 -4.92 1.43 1.0 6.89 7.89 -0.93 7.819 100 6.39 0.00 0.49 2.22
12.500 0.250 8.950 8.510 -1.950 -0.700 11.86 0.44 12.30 -5.30 1.60 1.0 7.00 8.00 -0.87 7.876 100 6.52 0.44 6.96 0.04 2.08
12.750 0.250 8.720 8.000 -2.090 -0.434 11.99 0.46 12.45 -5.33 1.25 1.0 7.12 8.12 -0.81 7.933 100 6.60 0.46 7.05 0.07 2.14
13.000 0.250 8.420 7.900 -1.000 -0.463 11.92 0.00 -4.69 2.28 1.0 7.23 8.23 -0.75 7.989 80 6.56 0.00 0.68 2.89
13.250 0.250 6.770 9.620 -2.290 -1.039 12.19 1.20 13.39 -6.00 1.75 1.0 7.39 8.39 -0.66 8.049 80 6.85 1.12 7.97 -0.58 2.69
13.500 0.250 5.320 7.780 -0.950 0.164 12.25 0.00 -4.70 2.16 1.0 7.55 8.55 -0.56 8.109 80 7.10 0.00 0.45 2.65
13.750 0.250 7.330 8.740 -1.070 -0.291 12.43 0.00 -4.72 2.11 1.0 7.70 8.70 -0.47 8.170 80 7.30 0.00 0.40 2.61
14.000 0.250 5.040 7.880 -1.010 0.022 12.65 0.00 -4.79 1.90 1.0 7.86 8.86 -0.37 8.230 80 7.44 0.00 0.42 2.69
14.250 0.250 6.510 8.510 -1.120 -0.464 12.81 0.00 -4.80 1.80 1.0 8.02 9.02 -0.27 8.290 80 7.60 0.00 0.42 2.72
14.500 0.250 9.880 9.920 -0.890 1.057 12.87 0.00 -4.70 2.13 1.0 8.17 9.17 -0.18 8.350 80 7.78 0.00 0.39 2.63
14.750 0.250 6.550 8.820 0.050 0.567 13.09 0.11 13.20 -4.87 1.48 1.0 8.33 9.33 -0.08 8.410 80 8.08 0.11 8.18 0.14 2.13
15.000 0.250 10.620 10.560 -1.190 -0.769 13.08 0.11 13.19 -4.70 2.24 1.0 8.48 9.48 0.01 8.470 80 8.16 0.11 8.27 0.22 2.48
15.250 0.250 8.290 11.190 -0.540 0.216 13.29 0.49 13.78 -5.14 2.13 1.0 8.64 9.64 0.11 8.530 80 8.30 0.49 8.79 -0.15 2.47
15.500 0.250 11.010 6.600 -1.170 -0.354 13.49 0.49 13.98 -5.18 2.00 1.0 8.80 9.80 0.21 8.590 80 8.45 0.49 8.93 -0.13 2.42
15.750 0.250 10.380 11.230 0.090 0.637 13.69 0.00 -4.74 1.70 1.0 8.95 9.95 0.30 8.650 80 8.64 0.00 0.32 2.31
16.000 0.250 11.700 7.710 0.210 0.532 13.76 0.25 14.01 -4.90 2.12 1.0 9.11 10.11 0.40 8.710 80 8.77 0.25 9.02 0.09 2.45
16.250 0.250 11.300 7.910 -0.360 1.033 13.92 0.58 14.50 -5.24 2.18 1.0 9.27 10.27 0.50 8.771 80 8.91 0.58 9.49 -0.23 2.39
16.500 0.250 6.850 8.450 -0.490 0.008 14.16 0.00 -4.74 1.74 1.0 9.42 10.42 0.59 8.831 80 9.04 0.00 0.38 2.33
16.750 0.250 5.200 5.200 0.520 1.307 14.39 0.00 -4.81 1.89 1.0 9.58 10.58 0.69 8.891 80 9.34 0.00 0.24 2.32
17.000 OldQueensRoadBridge 0.250 8.260 11.980 -0.550 -0.182 9.780 14.50 0.09 14.59 -4.86 2.22 1.0 9.73 10.73 0.78 8.951 80 9.48 0.09 9.58 0.16 2.31
17.250 0.250 8.770 11.790 0.120 0.952 14.70 0.09 14.80 -4.91 2.36 1.0 9.89 10.89 0.88 9.011 80 9.62 0.09 9.71 0.18 2.27
17.500 0.250 7.700 11.470 -0.400 0.795 15.07 0.14 15.21 -5.17 1.18 1.0 10.05 11.05 0.98 9.071 80 9.79 0.15 9.94 0.11 2.05
17.750 0.250 9.220 12.540 0.030 1.613 15.08 0.15 15.23 -5.03 1.49 1.0 10.20 11.20 1.07 9.131 80 9.86 0.16 10.02 0.18 2.27
18.000 0.250 7.330 11.630 0.720 1.442 15.20 0.15 15.35 -4.99 1.01 1.0 10.36 11.36 1.17 9.191 80 9.97 0.16 10.13 0.23 2.28
18.250 0.250 9.340 6.590 0.920 1.459 15.23 0.30 15.52 -5.01 1.26 1.0 10.52 11.52 1.26 9.251 80 10.09 0.28 10.37 0.15 2.26
18.500 0.250 6.940 7.920 1.220 1.597 15.18 0.18 15.35 -4.68 2.27 1.0 10.67 11.67 1.36 9.311 70 10.04 0.19 10.23 0.44 3.03
18.750 BackroadBridge 0.250 15.240 15.240 2.000 2.061 14.240 15.49 0.18 15.66 -4.63 1.71 1.0 11.03 12.03 1.55 9.483 70 10.43 0.19 10.61 0.42 3.16
19.000 0.250 10.020 13.290 1.460 1.727 15.50 0.34 15.84 -4.45 2.46 1.0 11.39 12.39 1.73 9.655 70 10.71 0.40 11.11 0.27 3.46
19.250 0.250 9.710 9.900 1.640 1.713 15.77 0.34 16.11 -4.37 2.23 1.0 11.74 12.74 1.92 9.827 70 11.21 0.40 11.61 0.13 3.45
19.500 0.250 10.980 17.600 1.910 2.582 15.95 0.00 -3.85 2.48 1.0 12.10 13.10 2.10 9.999 70 11.74 0.00 0.36 3.20
19.750 0.250 12.890 13.240 1.970 2.471 16.15 0.32 16.46 -4.00 2.95 1.0 12.46 13.46 2.29 10.171 70 12.09 0.35 12.43 0.02 3.10
20.000 0.250 11.300 8.550 2.130 2.231 16.57 0.16 16.72 -3.91 2.56 1.0 12.81 13.81 2.47 10.343 70 12.52 0.17 12.69 0.12 3.00
20.250 0.250 10.940 9.530 1.570 2.008 16.89 0.16 17.05 -3.87 1.97 1.0 13.17 14.17 2.66 10.515 70 12.90 0.17 13.07 0.10 2.72
20.500 0.250 10.280 12.000 2.380 2.787 17.05 0.00 -3.52 1.85 1.0 13.53 14.53 2.84 10.687 70 13.21 0.00 0.32 2.68
20.750 0.250 13.910 12.710 3.030 3.198 17.15 0.00 -3.26 2.07 1.0 13.89 14.89 3.03 10.859 70 13.50 0.00 0.39 2.85
21.000 0.250 13.770 14.420 2.860 3.516 17.36 0.00 -3.11 1.49 1.0 14.24 15.24 3.21 11.031 65 13.89 0.00 0.35 2.41
21.250 0.250 14.500 13.610 3.290 3.708 17.42 0.00 -2.82 1.63 1.0 14.60 15.60 3.40 11.203 65 13.99 0.00 0.61 3.30
21.500 0.250 14.690 12.800 3.710 4.122 17.53 0.00 -2.58 1.63 1.0 14.96 15.96 3.58 11.375 65 14.57 0.00 0.39 2.78
21.750 0.250 17.040 12.950 3.730 4.116 17.62 0.15 17.77 -2.45 1.94 1.0 15.31 16.31 3.77 11.547 65 14.89 0.15 15.05 0.27 2.88
22.000 0.250 11.510 10.250 3.630 3.745 17.80 0.15 17.95 -2.27 1.69 1.0 15.67 16.67 3.95 11.719 65 15.28 0.15 15.44 0.24 2.47
22.250 0.250 12.390 15.760 3.610 5.316 17.92 0.08 18.00 -1.97 1.29 1.0 16.03 17.03 4.14 11.891 65 15.61 0.08 15.69 0.34 1.55
22.500 0.250 13.270 14.550 4.060 4.353 17.94 0.08 18.02 -1.63 1.82 1.0 16.39 17.39 4.32 12.063 65 15.42 0.08 15.50 0.89 3.46
22.750 遊水地B越流堤 0.250 15.930 13.120 3.530 4.097 17.000 18.06 0.45 18.51 -1.77 1.96 1.0 16.74 17.74 4.51 12.235 65 16.11 0.46 16.57 0.17 2.41
23.000 0.250 12.600 14.080 3.470 4.401 18.12 0.00 -1.02 2.35 1.0 17.10 18.10 4.69 12.407 16.24 0.00 0.86 2.84
23.250 0.250 14.230 12.240 4.360 4.812 18.34 0.00 -0.99 2.03 1.0 17.35 18.35 4.88 12.471 16.61 0.00 0.74 2.43
23.500 0.250 13.170 17.840 3.950 4.254 18.47 0.27 18.74 -1.14 2.21 1.0 17.60 18.60 5.06 12.536 16.84 0.27 17.11 0.49 2.59
23.750 0.250 14.560 12.350 3.760 4.100 18.71 0.27 18.98 -1.13 1.85 1.0 17.85 18.85 5.25 12.601 17.21 0.27 17.48 0.38 2.17
24.000 0.250 12.920 13.110 5.220 5.562 18.64 0.00 -0.54 3.08 1.0 18.10 19.10 5.43 12.666 17.15 0.00 0.95 3.58
24.250 0.250 15.850 19.040 4.480 5.384 19.19 0.05 19.24 -0.89 1.83 1.0 18.35 19.35 5.62 12.731 17.93 0.05 17.98 0.37 2.13
24.500 0.250 12.750 16.240 5.510 5.928 19.25 0.05 19.30 -0.70 2.40 1.0 18.60 19.60 5.81 12.796 18.05 0.05 18.09 0.51 2.75
24.750 0.250 18.600 16.030 5.950 6.508 19.54 0.05 19.59 -0.74 1.77 1.0 18.85 19.85 5.99 12.860 18.46 0.05 18.51 0.34 1.98
25.000 0.250 30.760 16.360 4.870 5.363 19.54 0.41 19.96 -0.86 2.34 1.0 19.10 20.10 6.18 12.925 18.48 0.42 18.90 0.20 2.58
25.250 0.250 15.400 13.420 5.700 6.132 19.786 0.00 -0.44 1.73 1.0 19.35 20.35 6.36 12.990 18.789 0.00 0.56 1.90
25.500 0.250 19.000 19.210 5.310 6.107 19.919 0.00 -0.32 1.38 1.0 19.60 20.60 6.55 13.055 18.953 0.00 0.65 1.56
25.750 0.250 14.823 27.190 5.870 6.105 20.009 0.03 20.04 -0.34 1.28 1.0 19.70 20.70 6.80 12.901 19.08 0.03 19.11 0.59 1.41
26.000 0.250 16.820 27.540 6.400 7.812 20.085 0.03 20.11 -0.32 1.19 1.0 19.79 20.79 7.05 12.747 19.176 0.03 19.21 0.59 1.37
26.250 0.250 26.450 18.850 6.203 6.673 20.133 0.08 20.21 -0.32 1.40 1.0 19.89 20.89 7.30 12.593 19.254 0.08 19.34 0.55 1.55
26.500 0.250 19.220 17.730 5.930 6.847 20.241 0.08 20.32 -0.34 1.03 1.0 19.99 20.99 7.55 12.439 19.392 0.08 19.47 0.51 1.15
26.750 0.250 20.230 25.280 7.140 7.381 20.265 0.06 20.32 -0.24 1.37 1.0 20.08 21.08 7.80 12.286 19.429 0.06 19.49 0.59 1.53
27.000 0.250 31.990 21.330 7.220 7.586 20.339 0.06 20.40 -0.22 1.47 1.0 20.18 21.18 8.05 12.132 19.529 0.06 19.59 0.59 1.61
27.060 0.060 32.000 20.770 6.050 7.059 20.366 0.00 -0.17 1.42 1.0 20.20 21.20 8.11 12.095 19.565 0.00 0.64 1.55
27.250 0.190 32.840 20.220 7.512 7.687 20.466 0.09 20.56 -0.29 1.11 1.0 20.27 21.27 8.30 11.978 19.685 0.10 19.78 0.49 1.22
27.500 0.250 23.710 16.230 8.120 9.156 20.54 0.10 20.64 -0.27 0.89 1.0 20.37 21.37 8.55 11.824 19.776 0.10 19.87 0.50 0.99
27.750 0.250 25.660 21.220 8.180 8.522 20.575 0.00 -0.11 1.30 1.0 20.47 21.47 8.80 11.670 19.82 0.00 0.65 1.48
28.000 0.250 28.300 19.350 8.430 9.132 20.699 0.00 -0.14 0.96 1.0 20.56 21.56 9.05 11.516 19.987 0.00 0.58 1.06
28.250 0.250 33.570 22.178 8.566 8.908 20.699 0.11 20.81 -0.15 1.61 1.0 20.66 21.66 9.30 11.362 19.997 0.11 20.11 0.55 1.76
28.500 0.250 46.710 22.050 9.440 10.625 20.826 0.11 20.94 -0.18 1.47 1.0 20.75 21.75 9.55 11.209 20.154 0.11 20.26 0.49 1.64
28.750 0.250 25.620 30.300 9.611 10.714 20.937 0.12 21.05 -0.20 1.11 1.0 20.85 21.85 9.80 11.055 20.298 0.12 20.42 0.44 1.20
830 1/2600
1/1000
1/1000
1600
1000
2400
1400
1/1600 1/2600
1/2150 1/4200
1/700
1/1350
milepost
Current feature Design feature
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(2) Design Embankment Height (Free-Board)
In accordance with “Cabinet Order concerning Structural Standards for River Management Facilities,
etc. Chapter III Article 20”, the design embankment height is provided with a freeboard 1.0m for a
given flow rate as below.
Table 18-2 Design Embankment Free-Board
Item 1 2 3 4 5 6
Flow Rate
(m3/s) Less than 200
More than 200
Less than 500
More than 500
Less than 2000
More than 2000
Less than 5000
More than 5000
Less than 1000
More than
10000
Free Board
(m) 0.6 0.8
1 1.2 1.5 2
Source: “Cabinet Order concerning Structural Standards for River Management Facilities, etc. Chapter III Article 20”
(3) Design Riverbed Height
The design riverbed height is set up nearly the present riverbed height. The design riverbed slope is set up
nearly the present riverbed slope on due consideration of ensuring stability of the riverbed.
(4) Water Level Rise
The water level rise due to bridge pier, or due to the confluence point are considered but the water
level rising amount due to curvature is corresponded by the correction of cross-shape or planar normal
line if necessary, after checking the terrain situation behind the ground. In case that the water level is
over HWL and there are no protection objects, the water level rising is confirmed within the free-board.
This is considered a tentative situation in the step wise implementation so that the alignment is not
revised. Water Level Rise is mentioned in Table 18-1.
18.1.4 Cross-Sectional Plan
(1) Slope Gradient
a) From 8.0k(Downstream beginning point of Dike)to 18.75k(Back Road Bridge)
Although in principle the slope gradient of embankment is set loosely than 1:3 of either river side or land
side slope based on River Embankment Design Criteria in Japan, 2007, River Improvement and
Management Division, Water and Disaster Management Bureau, Ministry of Land, Infrastructure,
Transport and Tourism, Slope gradient either river side or land side for Nadi River is set as 1:2 because
1)Risk of dike breach due to riverbank erosion is low because cross-sectional shape of Nadi River after
improvement is almost engraved to existing ground, 2)Height of embankment is from 0.5m to 3m if
necessary and stability for structural and permeability is considered to be secured and 3) The present
situation of the bank are considered to be stable with almost 1:2 through field investigation.
In addition, in this project, slope of land side is hardly formed because low land area besides embankment
is filled with soil as mentioned later in "(4) Backfilling at Hinterland".
Typical Cross Section is as described in Figure 18-9.
On the other hand, slope gradient for other structures are set as below. Although details of each shape of
structure are mentioned later in each clause, only outline is described for reference in this clause.
b) Surrounding Dike of Nadi Town
Either river or land side of slope gradient is set as 1:3 because conditions do not apply to those mentioned
in above a).
c) Ring Dike
Either river or land side of slope gradient is set as 1:3 because conditions do not apply to those mentioned
in above a).
d) Surrounding Dike for Retarding Basin A,B in upstream
Either river or land side of slope gradient is set as 1:3 because conditions do not apply to those mentioned
in above a).
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e) Dike along the river for Retarding Basin A, B in upstream
Either river or land side of slope gradient is set as 1:3 because conditions do not apply to those mentioned
in above a).
(2) Top of Bank Width
In accordance with “Cabinet Order concerning Structural Standards for River Management Facilities,
etc. Chapter III Article 21”, the embankment section is provided with a bank width for a given flow
rate as mentioned in Table 18-3. Bank width is set as 4.0m
Table 18-3 Top of Bank Width
Design Discharge
(m3/s)
Bank Width
(m)
Less than 500 3
Moe than 500, Less than 2000 4
Moe than 2000, Less than 5000 5
Moe than 5000, Less than 10000 6
Moe than 10000 7 Source: “Cabinet Order concerning Structural Standards for River Management Facilities, etc. Chapter III Article 21”
(3) Inspection passage
In accordance with “Cabinet Order concerning Structural Standards for River Management Facilities,
etc. Chapter III Article 27”, the embankment is provided a inspection passage. Inspection passage
width is set as 3.0m
Table 18-4 Inspection Passage (Cabinet Order concerning Structural Standards for River
Management Facilities, etc. Chapter III Article 27 and Rules Article 15)
(Inspection Passage)
Article 27: Inspection Passage shall be installed near Embankment.
Rules Article 15: Width od Inspection Passage of Embankment is more than 3m and less than width of
crest of Embankment
Source: Edited by JICA Study Team from “Cabinet Order concerning Structural Standards for River Management Facilities,
etc. Chapter III Article 21”
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Figure 18-9 Typical Cross Section (Nadi River)
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(4) Backfilling at Hinterland
Terrain of the project area is the shape of a river terrace and the ground elevation is generally higher as
distance to land side from the river. Therefore, backfilling at hinterland is planned in order to the fill lower
area between embankment and land side if any after installation of embankment, also aiming at 1)
Improvement of safety degree for inundation (Land raising becomes hard to be inundated), 2) Cost
reduction by reducing disposal cost for soil generated by construction by utilizing them to backfilling. This
matter is already coordinated with the C/P of Fiji side.
In addition, for project costing, the backfilling cost is considered as project cost but land acquisition cost
for hinter land is not considered because whether backfilling of hinterland is conducted or not actually is
depending on intention of land owners. Land acquisition is conducted up to the land side end of
embankment.
(5) Riverbank Protection
Riverbank Protection is basically installed when flood flow velocity is more than 2.0m/s in Japan. However,
riverbank protection is not planned at the moment but considered adaptively although the flood flow
velocity is more than 2.0m/s in some sections in Nadi River after the Priority Project. Adaptively, river
bank protection is installed after extreme bank erosion occurs, and a margin in the cross section is left at
outer side of river channel curve such as leave bank as a margin for erosion considering flow capacity or
setting-back of embankment considering land acquisition cost.
<The reason for the adaptive management of riverbank protection>
1) During the past maximum flood, extreme riverbank erosion does not occur
2) River bank protection can be expected by vegetation because vegetation is flourished on the banks,
3) Installation of riverbank protection will cause riverbank erosion negatively near the installation area.
In addition, detailed planning of cross section mentioned above shall be done in Detailed Design Stage. At
this moment, typical cross section is applied for the project costing because construction cost for typical
cross section is supposed to be higher than that of cross-section mentioned in above.
Results of flood flow velocity with calculation conditions are mentioned in Table 18-5.
As the external force, the rainfall scale is same as that of design flood (1/50). The shape of river channel
and roughness coefficient (composite roughness coefficient) is assumed in the river channel after
improvement.
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Table 18-5 Flood Flow velocity
Water DepthDegree of
roughness
Energy
Gradient
Velocity
(Average)
Velocity
(left bank
side)
Velocity
(right bank
side)
Water DepthDegree of
roughness
Energy
Gradient
Velocity
(Average)
Velocity
(left bank
side)
Velocity
(right bank
side)
a) Past
damage,
bank
erosion
b) Outer
bending and
asset
existing
c) Bridge
Protection
0.000 1.19 0.015 0.000138590 1.87 1.71 1.71 1.18 0.015 0.0002002 2.11 1.92 1.91
0.250 0.99 0.015 0.000251510 2.89 2.55 2.51 0.76 0.015 0.0008487 4.26 4.15 3.94
0.500 1.00 0.015 0.000331090 3.12 2.55 2.80 0.78 0.015 0.0013184 4.83 4.69 4.44
0.750 1.16 0.015 0.000287200 2.92 2.52 2.43 1.12 0.015 0.0008716 3.98 3.73 3.68
1.000 1.24 0.015 0.000291770 2.92 2.59 2.56 1.24 0.015 0.0011985 4.31 3.95 3.97
1.250 1.35 0.015 0.000257390 2.81 2.53 2.33 1.91 0.015 0.0003348 2.87 2.78 2.81
1.500 1.57 0.015 0.000145340 2.19 2.08 1.87 2.19 0.015 0.0001361 2.03 1.98 2.00
1.750 1.47 0.015 0.000245450 2.79 2.27 2.47 2.05 0.015 0.0002684 2.80 2.37 2.59
2.000 1.57 0.015 0.000239590 2.69 2.36 2.52 2.10 0.015 0.0003398 2.94 2.65 2.79
2.250 1.68 0.015 0.000221760 2.53 2.09 2.41 2.34 0.015 0.0001839 2.30 1.95 2.24
2.500 1.74 0.015 0.000186870 2.55 2.12 2.26 2.37 0.015 0.0001650 2.40 2.18 2.22
2.750 1.94 0.015 0.000122790 1.86 1.65 1.66 2.55 0.015 0.0000982 1.70 1.54 1.56
3.000 1.89 0.015 0.000177670 2.28 1.79 1.89 2.42 0.015 0.0002533 2.53 2.07 2.21
3.250 1.87 0.015 0.000224980 2.58 2.25 2.37 2.52 0.015 0.0002073 2.39 2.23 2.20
3.500 2.01 0.015 0.000170180 2.27 1.94 2.17 2.61 0.015 0.0001576 2.20 2.05 2.14
3.750 2.02 0.015 0.000214170 2.46 2.05 1.89 2.41 0.015 0.0004063 3.19 2.48 2.49
4.000 2.15 0.015 0.000163340 2.12 2.05 1.82 2.62 0.015 0.0003415 2.83 2.65 2.50
4.250 2.28 0.027 0.000521430 2.17 1.55 1.46 2.70 0.025 0.0011568 3.30 1.63 1.64
4.500 2.53 0.027 0.000449240 2.10 1.48 1.42 3.06 0.025 0.0010959 3.37 1.80 1.93
4.750 2.76 0.028 0.000537290 2.17 1.64 1.41 3.75 0.034 0.0014862 2.93 2.50 2.35
5.000 2.97 0.024 0.000301630 2.23 1.34 1.35 4.21 0.029 0.0006503 3.07 1.89 1.95
5.250 3.15 0.026 0.000280950 1.94 1.22 1.24 4.53 0.026 0.0005348 2.74 2.04 1.95
5.500 3.24 0.026 0.000353420 2.15 1.24 1.36 4.68 0.030 0.0012565 3.10 2.20 2.35
5.750 3.50 0.024 0.000082020 1.19 0.59 0.70 5.08 0.027 0.0003608 2.49 1.36 1.55 ○6.000 3.18 0.024 0.000575440 3.08 1.59 1.59 5.35 0.027 0.0012760 1.89 1.05 1.00
6.250 3.37 0.024 0.000555110 3.07 1.58 1.58 5.37 0.027 0.0007355 2.03 1.12 1.12
6.500 3.57 0.024 0.000497220 2.95 1.52 1.52 5.41 0.027 0.0010149 2.10 1.17 1.15
6.750 3.73 0.024 0.000478540 2.93 1.55 1.51 5.45 0.031 0.0007864 2.22 1.25 1.12 ○7.000 3.94 0.024 0.000381880 2.66 1.35 1.36 5.53 0.030 0.0008455 2.17 1.17 1.18 ○7.250 4.07 0.024 0.000365560 2.62 1.30 1.37 5.58 0.038 0.0003464 2.24 1.20 1.23
7.500 4.18 0.024 0.000391170 2.71 1.60 1.32 5.62 0.027 0.0004204 2.41 1.50 1.31
7.750 4.30 0.024 0.000390020 2.76 1.42 1.44 5.66 0.031 0.0003199 2.60 1.42 1.37
8.000 4.45 0.024 0.000360710 2.67 1.22 1.25 5.74 0.036 0.0002884 2.65 1.41 1.51
8.250 4.64 0.024 0.000310630 2.39 1.40 1.53 5.87 0.025 0.0002767 2.56 1.68 1.74
8.500 4.75 0.024 0.000334810 2.48 1.51 1.55 5.96 0.024 0.0004644 2.66 1.81 1.75
8.750 4.90 0.024 0.000314510 2.41 1.47 1.47 6.10 0.027 0.0005329 2.60 1.75 1.78 ○ ○9.000 5.05 0.024 0.000269650 2.29 1.41 1.47 6.23 0.027 0.0003936 2.51 1.72 1.74
9.250 5.17 0.024 0.000251270 2.19 1.43 1.18 6.36 0.033 0.0003575 2.36 1.58 1.49 ○9.500 5.26 0.024 0.000259360 2.25 1.45 1.35 6.45 0.027 0.0002866 2.41 1.74 1.33 ○9.750 5.36 0.024 0.000260990 2.27 1.41 1.39 6.57 0.027 0.0002083 2.44 1.93 1.56 ○ ○ Riverbank Protection
9.830 5.51 0.024 0.000218160 2.16 1.13 6.72 0.026 0.0001664 2.35 1.54 0.72
10.000 5.54 0.024 0.000251240 2.26 1.41 1.43 6.74 0.026 0.0004769 2.48 1.71 1.65
10.250 5.65 0.024 0.000246870 2.21 1.37 1.36 6.86 0.028 0.0011888 2.41 1.60 1.62 ○ ○10.500 5.76 0.024 0.000233430 2.18 1.33 1.39 6.96 0.027 0.0001672 2.39 1.60 1.63 ○10.750 5.85 0.024 0.000230050 2.18 1.38 1.33 7.04 0.029 0.0001803 2.40 1.67 1.60
11.000 5.97 0.024 0.000158780 1.98 1.07 1.11 7.17 0.027 0.0001161 2.21 1.45 1.49
11.250 5.99 0.025 0.000254200 2.25 1.40 1.40 7.18 0.028 0.0002095 2.46 1.70 1.67 ○ ○11.500 6.12 0.024 0.000210810 2.12 1.35 1.34 7.30 0.032 0.0001539 2.35 1.64 1.60
11.750 6.19 0.025 0.000245230 2.23 1.40 1.38 7.37 0.029 0.0002385 2.45 1.71 1.67
12.000 6.30 0.025 0.000231890 2.18 1.35 1.36 7.47 0.026 0.0001226 2.39 1.64 1.65
12.250 6.39 0.025 0.000241600 2.22 1.38 1.38 7.55 0.030 0.0001504 2.45 1.67 1.70
12.500 6.52 0.025 0.000194970 2.08 1.28 1.32 7.67 0.027 0.0001419 2.32 1.56 1.62
12.750 6.60 0.025 0.000225310 2.14 1.27 1.32 7.76 0.029 0.0001052 2.34 1.48 1.59 ○13.000 6.56 0.025 0.000451550 2.89 1.86 1.86 7.67 0.027 0.0003192 3.18 2.23 2.23 ○13.250 6.85 0.025 0.000370880 2.69 1.78 2.01 7.95 0.032 0.0002586 2.94 2.19 2.34 ○ ○13.500 7.10 0.025 0.000377600 2.65 1.85 1.99 8.16 0.027 0.0002751 2.93 2.24 2.35
13.750 7.30 0.025 0.000333760 2.61 1.68 1.74 8.33 0.029 0.0003270 2.95 2.09 2.13
14.000 7.44 0.025 0.000354970 2.69 1.83 1.73 8.46 0.031 0.0003051 3.05 2.24 2.14
14.250 7.60 0.025 0.000338180 2.72 1.78 1.84 8.61 0.030 0.0002225 3.12 2.23 2.27
14.500 7.78 0.025 0.000333640 2.63 1.73 1.77 8.80 0.027 0.0002785 2.99 2.13 2.18
14.750 8.08 0.027 0.000286400 2.13 1.40 1.75 9.15 0.031 0.0001422 2.33 1.71 2.03
15.000 8.16 0.026 0.000284940 2.48 1.64 1.71 9.16 0.032 0.0004092 2.86 2.06 2.12
15.250 8.30 0.025 0.000273310 2.47 1.63 1.63 9.31 0.029 0.0002953 2.82 2.03 2.02 ○15.500 8.45 0.026 0.000276110 2.42 1.66 1.63 9.45 0.031 0.0003191 2.77 2.04 2.03
15.750 8.64 0.026 0.000290330 2.31 1.57 1.81 9.66 0.034 0.0002585 2.55 1.93 2.12 ○16.000 8.77 0.025 0.000278160 2.45 1.62 1.61 9.75 0.033 0.0003857 2.80 2.00 2.02
16.250 8.91 0.025 0.000251170 2.39 1.63 1.56 9.89 0.027 0.0002621 2.76 2.02 1.97
16.500 9.04 0.025 0.000237910 2.33 1.57 1.54 10.03 0.032 0.0002635 2.69 1.96 1.93
16.750 9.34 0.026 0.000245740 2.32 1.56 1.53 10.40 0.029 0.0002078 2.64 2.13 2.09 ○ Riverbank Protection
17.000 9.48 0.026 0.000241060 2.31 1.72 1.74 10.54 0.032 0.0003910 2.62 2.10 2.09
17.250 9.62 0.025 0.000218610 2.27 1.52 1.48 10.67 0.029 0.0003734 2.59 1.90 1.84
17.500 9.79 0.027 0.000221150 2.05 1.66 1.50 10.86 0.034 0.0001059 2.33 1.98 1.84
17.750 9.86 0.026 0.000231610 2.27 1.61 1.50 10.90 0.028 0.0001189 2.60 1.98 1.85
18.000 9.97 0.026 0.000233340 2.28 1.48 1.52 11.02 0.037 0.0001030 2.60 1.85 1.90
18.250 10.09 0.025 0.000205930 2.26 1.48 1.52 11.13 0.036 0.0001517 2.61 1.85 1.89
18.500 10.04 0.026 0.000441550 3.03 2.14 2.13 11.01 0.031 0.0003711 3.51 2.66 2.65
18.750 10.43 0.025 0.000526450 3.16 1.92 2.11 11.50 0.031 0.0001821 3.51 2.66 2.81
19.000 10.71 0.028 0.000704840 2.74 2.29 2.29 11.72 0.030 0.0004255 3.08 2.69 2.69
19.250 11.21 0.028 0.000678190 2.66 2.23 2.23 12.13 0.031 0.0003281 3.01 2.63 2.63
19.500 11.74 0.028 0.000585680 2.59 2.17 2.17 12.67 0.034 0.0005938 2.95 2.58 2.58
19.750 12.09 0.028 0.000496610 2.70 2.24 2.27 13.06 0.031 0.0006562 3.10 2.68 2.72
20.000 12.52 0.028 0.000468760 2.47 2.09 2.09 13.42 0.031 0.0004566 2.84 2.49 2.49
20.250 12.90 0.028 0.000378190 2.44 2.06 2.06 13.83 0.031 0.0002452 2.81 2.47 2.47
20.500 13.21 0.029 0.000442940 2.39 2.02 2.02 14.11 0.035 0.0003203 2.88 2.53 2.53
20.750 13.50 0.029 0.000438930 2.37 2.01 2.01 14.36 0.030 0.0002652 2.86 2.51 2.51
21.000 13.89 0.028 0.000312890 2.57 2.24 2.24 14.84 0.028 0.0001203 3.10 2.78 2.78
21.250 13.99 0.030 0.000682360 2.51 2.19 2.19 14.80 0.029 0.0001786 3.02 2.72 2.72
21.500 14.57 0.030 0.000455850 2.46 2.14 2.14 15.49 0.031 0.0002128 2.96 2.66 2.66
21.750 14.89 0.030 0.000484000 2.41 2.11 2.11 15.79 0.028 0.0002408 2.90 2.62 2.62
22.000 15.28 0.028 0.000269290 2.37 2.08 2.08 16.19 0.031 0.0002098 3.00 2.71 2.71
22.250 15.61 0.027 0.000105960 2.34 2.05 2.05 16.68 0.026 0.0000832 2.95 2.66 2.66
22.500 15.42 0.031 0.000767510 2.31 2.03 2.03 16.18 0.034 0.0003624 2.90 2.62 2.62
22.750 16.11 0.031 0.000323530 2.63 2.31 2.31 17.27 0.031 0.0002048 2.86 2.59 2.59
23.000 16.24 0.030 0.000425690 2.57 2.26 2.26 17.32 0.030 0.0002858 2.82 2.55 2.55
23.250 16.61 0.033 0.000368010 2.52 2.22 2.22 17.67 0.032 0.0002463 2.79 2.53 2.53
23.500 16.84 0.043 0.000743410 2.47 2.18 2.18 17.83 0.039 0.0004763 2.76 2.50 2.50
23.750 17.21 0.035 0.000339860 2.44 2.15 2.15 18.06 0.034 0.0003705 3.43 3.11 3.11
24.000 17.15 0.031 0.000754130 2.39 2.10 2.10 17.67 0.030 0.0009251 3.31 3.00 3.00
24.250 17.93 0.031 0.000259490 2.13 1.81 1.82 19.16 0.031 0.0002862 2.81 2.53 2.46
24.500 18.05 0.035 0.000567050 2.75 2.50 2.46 19.17 0.033 0.0006263 3.71 3.46 3.41
24.750 18.46 0.028 0.000160740 1.98 1.68 1.56 19.79 0.028 0.0001944 2.65 2.33 2.22
25.000 18.48 0.028 0.000254140 2.58 2.07 2.15 19.72 0.028 0.0003298 3.52 2.94 3.07
25.250 18.789 0.029 0.000141620 1.90 1.25 1.20 20.22 0.029 0.0001745 2.55 2.24 2.21
25.500 18.953 0.035 0.000190190 1.56 1.44 1.30 20.39 0.037 0.0004362 2.73 2.55 2.34
25.750 19.08 0.038 0.000159340 1.41 1.29 1.26 20.73 0.039 0.0003746 2.50 2.32 2.24
26.000 19.176 0.034 0.000154170 1.37 1.10 1.23 21.02 0.036 0.0002938 2.21 1.88 1.99
26.250 19.254 0.037 0.000199370 1.55 1.42 1.37 21.16 0.038 0.0004327 2.63 2.39 2.40
26.500 19.392 0.036 0.000100130 1.15 0.96 1.02 21.53 0.037 0.0001997 1.88 1.63 1.71
26.750 19.429 0.039 0.000233720 1.53 1.40 1.38 21.59 0.041 0.0004495 2.48 2.32 2.26
27.000 19.529 0.035 0.000188490 1.61 1.42 1.38 21.79 0.036 0.0003845 2.66 2.40 2.33
27.060 19.565 0.039 0.000209760 1.55 1.43 1.36 21.87 0.039 0.0004413 2.60 2.43 2.32
27.250 19.685 0.049 0.000242170 1.22 1.12 1.21 22.20 0.050 0.0004446 1.86 1.81 1.82
27.500 19.776 0.040 0.000107270 0.99 0.83 0.93 22.40 0.041 0.0001772 1.49 1.28 1.46
27.750 19.82 0.040 0.000311820 1.48 1.37 1.33 22.51 0.043 0.0004541 1.91 1.86 1.70
28.000 19.987 0.036 0.000104720 1.06 0.87 0.95 22.76 0.038 0.0001604 1.57 1.37 1.41
28.250 19.997 0.040 0.000341880 1.76 1.62 1.61 22.73 0.040 0.0006072 2.64 2.53 2.41
28.500 20.154 0.029 0.000165340 1.64 1.06 1.34 23.10 0.031 0.0002372 2.21 1.72 1.66
28.750 20.298 0.030 0.000085830 1.20 0.95 0.87 23.35 0.031 0.0001313 1.71 1.26 1.36
Location
Flood Flow Velocity1)
Conditions near river channel
Riverbank Protection
Master Plan Priority Project
Adaptive management of
riverbank protection2)
Adaptive management of
riverbank protection
1)At hatching section in above table, the flow rate exceeds 2.0 m/s
2) Riverbank protection is considered adaptively, if necessary in the future, river bank protection shall be installed
Adaptive management of
riverbank protection
Adaptive management of
riverbank protection
Adaptive management of
riverbank protection
Adaptive management of
riverbank protection
Vel
oci
ty(
m)
Current River Channelsection
Transitionsection
River Widening Section
Retarding basinSection
Current River Channelsection
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18.2 Retarding Basin A, B
Retarding Basin A and B temporarily storage 80 m3/s in Retarding Basin A and 510 m3/s in Retarding
Basin B of flood discharge volume 2,450 m3/s before flood control, and flow 1,800m3/s at Back Road
Bridge with full in order to prevent inundation in Important Protected Area in Nadi River Basin.
No.25 2012年3月洪水
NawakaRiver NamosiRiver
[3,650]
1,000
[900]
900
[1,450]
1,000
NadiRiverNaditownBridge BackroadBridge
[2,450]
1,400
[2,450]
1,400
[2,450]
1,600[1,750]
830
Votualevu
[上段]:基本高水
下段:整備後流量(MP)
[3,650]
2,400
B
A
-200
-40
V=6,520千m3
V=640千m3
-1400
NawakaRiver NamosiRiver
[3,650]
1,000
[900]
730
[1,450]
1,130
NadiRiverNaditownBridge BackroadBridge
[2,450]
1,800
[2,450]
1,800
[2,450]
2,450[1,750]
1,740
Votualevu
[上段]:基本高水
下段:整備後流量(優先プロジェクト)
[3,650]
2,950
B
A
-510
-80
V=7,200千m3
V=1,000千m3
NawakaRiver
[Upper]: Discharge before Flood Control
[Lower]: Design Discharge after the Priority Project
V=7,200 thousand m3
V=1,000 thousand m3
Figure 18-10 Designed Discharge Distribution at the Priority Project
Although these basins are filled with flood water when large scale flood (more than 1/10 design return
period) occurs, flood water is drained to the river after flood and after clearing, basins become like normal
condition and it also becomes possible to cultivate. In addition, the river dike (surrounding dike of retarding
basins) is constructed together with the retarding basins so that the inundation damages by small scale flood
are reduced.
18.2.1 Retarding Basin A
(1) Layout and Facilities Design
Layout and Facilities Design is conducted considering ensuring of flood control discharge at the Priority
Project and smooth intake of peak cut discharge 80m3/s to the basin. In order to secure flood control
discharge, location of overflow dike is set at 20.5km of Nadi River.
Specifications of the basin are set in order to secure peak cut discharge through hydrological analysis. Peak
cut discharge, flood control discharge and outflow rate is set as mentioned in Table 18-6. Specifications of
drainage sluice gate (the number of gates, outflow rate) are set as a scale that flood water in the basin can
be drained within 24 hours2.
2 The reason is that the second peak of rainfall occurred 24 hours later and the durable inundated hours of sugar cane is
approximately 72 hours.
Table 18-6 Specifications for Retarding Basin A at the Priority Project
Retarding Basin A
Location Leftbank Side: 18.75k~21.0k
Flood Control Discharge(1000m3) 996
Peak Cut Discharge(m3/s) 80
Peak water level in the basin by calculation(EL.m) 14.50
60m
20.455~20.5k
13.53
(20.5k HWL)
Peak water level at overflow dike by calculation(EL.m) 14.51
Overflow Depth (m) 0.98
14.53
(20.5k Design Embannkment Height)
B1.5×H1.5×1Gate
Elevation of the bottom of drainage
waterway EL. 9.59 m
Outflow Rate Q=10.9m3/s
Drainage Time t=17.0 hrs
Length and Location of Overflow Dike
Elevation of the top of Overflow Dike(EL.m)
Design Elevation of Height of Embankment
surrounding the basin(EL.m)
Specifications of dicharge.
In addition, ground elevation in the basin is high in some part (high terrace). Therefore, high-level terrace
in the basin is excavated 1.5m to the bottom such as stripping topsoil and leveling in order to secure flood
control discharge in the basin4Layout of Retarding Basin A is as shown in Figure 18-11.
※Flow volume after the priority project include natural
flood volume at outside section of Important Protected Area
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Figure 18-11 Layout of Retarding Basin A 4 In the time of this study the area inside the retarding basin is to be done an acquisition by the intension of Ministry of Land, Fiji so that the compensation for crops is not required. In the detail design stage in future , in case that the easement is set instead of land acquisition, the compensation for crops will be necessary (same as the retarding B).
(2) Cross-Sectional Plan Either river or land side of slope gradient or surrounding dike and dike along the river are set as 1:3 based on River Embankment Design Criteria in Japan, 2007, River Improvement and Management Division, Water and Disaster Management Bureau, Ministry of Land, Infrastructure, Transport and Tourism. (see 18.1.4(1)a)
Bank width is set as 4.0m based on “Cabinet Order concerning Structural Standards for River Management Facilities, etc. Chapter III Article 21” . (see 18.1.4 (2))
Typical Cross Section is mentioned in Figure 18-12.
Retarding Basin B
Votualevu
Nasau
Nadi river Over Flow Dike (Intake)
Retarding Basin A
Outlet
Outlet
Over Flow Dike (Intake)
Meiganiyah
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Figure 18-12 General Plan of Retarding Basin A
Sluiceways of Drainage
Over Flow Dike
Plan View
Typical cross section
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Overflow- Dike
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▼HWL 13.53m ▼EL. 14.53m
▼Design Bank Height 14.53m
▼EL. 9.59m
▼HWL 13.53m
▼HWL 13.53m
Nadi River
Longitudinal Plan
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20.0
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Eleva
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m)
km
Design Embankment Height HWL
Design Riverbed (after improvement) Ground Elevation at Right Bank
Ground Elevation at Left Bank Side Average Riverbed Elevation
Lowest Riverbed Elevation Calculation Water Level for Design Flood Discharge(Planned River)
Gradient of Design Riverbed=1/2,600Gradient of Design Riverbed=1/1,350
Gradient of HWL=1/1,600 Gradient of HWL=1/700 Gradient of HWL=1/1000
Retarding Basin A
Over Flow Dike A
20.455~20.50kEL.13.53m
Drainage Sluise A19.13kEL.9.59m
Retarding Basin B
Over Flow Dike B
19.75~24.10kEL. 17.25m
Drainage Sluise B19.13kEL.8.2m
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Figure 18-13 Typical Cross Section (Retarding Basin A,B)
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(3) Overflow Dike
Specifications of overflow dike are set in order to secure peak cut discharge.
Concrete facing structure is applied for basic structure of overflow dike because it can respond to relatively
severe hydraulic conditions and have strong durability, however there are some kinds of structures type
such as asphalt facing, concrete block facing and gabion facing.
In addition, the crest elevation of overflow dike is different between the Priority Project and Master Plan
because flood control discharge is different between them. Actually, flood control discharge at Master Plan
is lower than that at the Priority Project. Therefore, the crest elevation of overflow dike at Master Plan is
lower than that at the Priority Project and it is required to lower the crest elevation of overflow dike from
the Priority Project to Master Plan. In such a situation, it is planned that basic specifications of overflow
dike follows the those at Master Plan and L-shaped retaining wall is installed on the top of overflow dike in
order to secure the crest elevation at the Priority Project and can be removed at Master Plan. Details are
verified in detailed design stage.
Typical Cross Section of overflow dike is mentioned in Figure 18-13. The basic design of the over flow
dike is as shown in Figure 18-16 in case of larger scale retarding basin B.
Figure 18-14 Typical Cross Section of Overflow Dike for Retarding Basin A
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Figure 18-15 General Plan of Overflow Dike for Retarding Basin A
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18.2.2 Retarding Basin B
(1) Layout and Facilities Design
Layout and Facilities Design is conducted considering ensuring of flood control discharge at the Priority
Project and smooth intake of peak cut discharge 510m3/s to the basin. In order to secure flood control
discharge, location of overflow dike is set at 24.0km of Nadi River.
Specifications of the basin are set in order to secure peak cut discharge through hydrological analysis. Peak
cut discharge, flood control discharge and outflow rate is set as mentioned in Table 18-7. Specifications of
drainage sluice gate (the number of gates, outflow rate) are set as a scale that flood water in the basin can
be drained within 24 hours3.
3 The reason is that the second peak of rainfall occurred 24 hours later and the durable inundated hours of sugar cane is
approximately 72 hours.
Table 18-7 Specifications for Retarding Basin B at the Priority Project
Retarding Basin B
Location Rightbank Side: 19.75k~24.10k
Flood Control Discharge(1000m3) 7,157
Peak Cut Discharge(m3/s) 510
Peak water level in the basin by calculation(EL.m) 18.50
300m
23.65k~23.95k
17.25
(23.75k HWL-0.4m)
Peak water level at overflow dike by calculation(EL.m) 18.89
Overflow Depth (m) 1.64
19.05
(23.95k Design Embannkment Height)
B2.5×H2.5×2Gates
Elevation of the bottom of drainage
waterway EL. 8.20 m
Outflow Rate Q=93.1m3/s
Drainage Time t=16.4 hrs
Length and Location of Overflow Dike
Elevation of the top of Overflow Dike(EL.m)
Design Elevation of Height of Embankment
surrounding the basin(EL.m)
Specifications of dicharge.
In addition, ground elevation in the basin is high in some part (high terrace). Therefore, high-level terrace
in the basin is excavated 1.0m to the bottom such as stripping topsoil and leveling in order to secure flood
control discharge in the basin.
Layout of Retarding Basin B is as shown in Figure 18-16.
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Figure 18-16 Layout of Retarding Basin B
(2) Cross-Sectional Plan Either river or land side of slope gradient or surrounding dike and dike along the river are set as 1:3 based on River Embankment Design Criteria in Japan, 2007, River Improvement and Management Division, Water and Disaster Management Bureau, Ministry of Land, Infrastructure, Transport and Tourism. (see 18.1.4(1)a)
Bank width is set as 4.0m based on “Cabinet Order concerning Structural Standards for River Management Facilities, etc. Chapter III Article 21” . (see 18.1.4 (2))
Typical Cross Section is mentioned before in Figure 18-12.
Retarding Basin B
Votualevu
Nasau
Nadi river Over Flow Dike (Intake)
Retarding Basin A
Outlet
Outlet
Over Flow Dike (Intake)
Meiganiyah
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Figure 18-17 General Plan of Retarding Basin B
SLUICEWAYS of Drainage
Over Flow Dike
Plan View
Typical cross section
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▼HWL 18.05m ▼EL. 19.05m
SLUICEWAYS of Drainage
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▼Design Bank Height 19.05m
▼HWL 18.05m
▼HWL 18.05m
Nadi River
Longitudinal Plan
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30.0
15.0 16.0 17.0 18.0 19.0 20.0 21.0 22.0 23.0 24.0 25.0
Eleva
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m)
km
Design Embankment Height HWL
Design Riverbed (after improvement) Ground Elevation at Right Bank
Ground Elevation at Left Bank Side Average Riverbed Elevation
Lowest Riverbed Elevation Calculation Water Level for Design Flood Discharge(Planned River)
Gradient of Design Riverbed=1/2,600Gradient of Design Riverbed=1/1,350
Gradient of HWL=1/1,600 Gradient of HWL=1/700 Gradient of HWL=1/1000
Retarding Basin A
Over Flow Dike A
20.455~20.50kEL.13.53m
Drainage Sluise A19.13kEL.9.59m
Retarding Basin B
Over Flow Dike B
19.75~24.10kEL. 17.25m
Drainage Sluise B19.13kEL.8.2m
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(3) Overflow Dike
Specifications of overflow dike are set in order to secure peak cut discharge.
Concrete facing structure is applied for basic structure of overflow dike because it can respond to relatively
severe hydraulic conditions and have strong durability, however there are some kinds of structures type
such as asphalt facing, concrete block facing and gabion facing.
In addition, the crest elevation of overflow dike is different between the Priority Project and Master Plan
because flood control discharge is different between them. Actually, flood control discharge at Master Plan
is lower than that at the Priority Project. Therefore, the crest elevation of overflow dike at Master Plan is
lower than that at the Priority Project and it is required to lower the crest elevation of overflow dike from
the Priority Project to Master Plan. In such a situation, it is planned that basic specifications of overflow
dike follows the those at Master Plan and L-shaped retaining wall is installed on the top of overflow dike in
order to secure the crest elevation at the Priority Project and can be removed at Master Plan. Details are
verified in detailed design stage.
Typical Cross Section of overflow dike is mentioned in Figure 18-15. The basic design of the over flow
dike is as shown in Figure 18-16.
Figure 18-18 Typical Cross Section of Overflow Dike for Retarding Basin B
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Figure 18-19 General Plan of Overflow Dike for Retarding Basin B
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18.3 Surrounding Dike of Nadi Town Surrounding Dike of Nadi Town is installed mainly in order to prevent flood water of Nawaka River from flowing into Important Protected Area where central of Nadi Town is located.
18.3.1 Plan Surrounding Dike of Nadi Town are embankments which are installed as a priority project ahead of other dikes in other sections at left bank side of Nadi River and at right bank side of Nawaka River in order to prevent flood water of Nawaka River from flowing into Important Protected Area.
The location of dike is determined based on the inundation analysis, the alignment is set along the present river avoiding housing relocation.
In the area of proposed right dike of Nawaka River, Nawaka River around Queens Road meanders complexly and the old river channel is also left. The area has a function of natural retarding basin at present so that retarding effect is expected in flooding time and also the review of alignments will be examined in the Master Plan in future, and it is not effective for the new dikes to meander complexly along the present river channel (from view point of construction). Therefore the alignment of new dike is determined separately from the present river channel in smooth shape avoiding the relocation of housing
Plan of Surrounding Dike is as described in Figure 18-20.
Surrounding Dike
Surrounding Dike
Nadi Town Bridge
Nadi Town
Nawaka Village
Hindu Temple
Nawaka River
Figure 18-20 Plan of Surrounding Dike
18.3.2 Longitudinal Plan The Height of surrounding dike of Nadi Town is basically set as the same height as that of Master Plan.
However, inundation depth after the Priority Project when historical maximum flood occurs will exceed the height of embankment of Nawaka River. This is why retarding basins in tributaries area which are proposed in Master Plan are not installed as the Priority Project and flood discharge of target design scale exceeds the level of embankment of Master Plan of Nawaka River just only after the Priority Project. Therefore, the height of surrounding dike along Nawaka River is set as the same height of inundation depth after the Priority Project.
The longitudinal plan is as shown in Table 18-8.
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Table 18-8 Longitudinal Plan of Surrounding Dike of Nadi Town
River Landside
1 Cross 1 6.36 5.76 - - 6.76
2 Nadi 9.75K 6.36 5.72 6.28 - 6.72
3 Nadi 9.50K 5.96 5.61 6.16 - 6.61
4 Cross 2 5.43 - - 5.73 6.67
5 Cross 3 3.31 - - 5.73 6.70
6 Cross 4 5.19 - - 5.73 6.74
7 Cross 5 5.28 - - 6.68 8.00
8 Nawaka 0.75K 5.44 5.79 6.72 6.68 8.00
9 Cross 6 6.14 - - 7.79 8.00
10 Nawaka 2.00K 6.20 7.26 - 8.68 9.00
11 Cross 7 6.24 - - 8.58 9.00
12 Nawaka 2.50K 6.50 - 8.78 8.67 9.00
13 Nawaka 2.25K 6.50 7.56 8.73 8.67 9.00
14 Cross 8 6.56 - - 8.76 9.00
15 Cross 9 6.62 - - 8.76 9.00
16 Nawaka 2.75K 6.80 8.15 8.79 8.77 9.15
17 Nawaka 3.25K 7.04 8.73 8.95 8.91 9.73
18 Nawaka 3.50K 6.23 9.03 9.09 9.02 10.03
19 Nawaka 3.75K 7.26 9.32 9.24 9.03 10.32
20 Nawaka 4.00K 6.93 9.62 9.84 9.40 10.62
21 Nawaka 4.25K 10.07 9.91 10.05 9.29 10.91
22 Nawaka 4.50K 8.25 10.20 10.85 9.73 11.20
23 Nawaka 4.75K 9.58 10.50 11.21 11.21 11.50
24 Nawaka 5.00K 10.94 10.79 11.60 11.23 11.79
25 Nawaka 5.25K 11.00 11.09 12.11 - 12.09
Setting Basis
Following the inundation depth
of landside when 1/50 flood
occurs
Following the elevation of the
crest of embankment of the
Nadi River
Following the elevation of the
crest of embankment of the
Nawaka River
No. Cross Section HWLInundation Depth by calculation when 1/50 flood occurs Proposed height of
Surrounding Dike
Existing
Ground
Level
Location of Queens Road
18.3.3 Cross-Sectional Plan
Either river or land side of slope gradient of surrounding dike and dike along the river are set as 1:3 based
on River Embankment Design Criteria in Japan, 2007, River Improvement and Management Division,
Water and Disaster Management Bureau, Ministry of Land, Infrastructure, Transport and Tourism. (see
18.1.4(1)a)
Bank width is set as 4.0m based on “Cabinet Order concerning Structural Standards for River Management
Facilities, etc. Chapter III Article 21” (see Table 18-3).
Typical Cross Section is mentioned before in Figure 18-18.
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Figure 18-21 Typical Cross Section (Surrounding Dike of Nadi Town)
Surrounding Dike
断側線位置図 Location of Cross Section
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18.4 Ring Dike Ring Dike is installed in order to prevent flood water from flowing into community which is located in downstream natural inundation area.
18.4.1 Plan Ring Dike is arranged in a way that surrounds the outer edge of the community to be protected. Access slope road from outer side of ring dike to inner side, drainage system and outlet is also installed.
Plan of Ring Dike is as shown in Figure 18-19.
Ring Dike
1.0K
CrossSection
Ring Dike
Slope
Outlet of drainage
Figure 18-22 Plan of Ring Dike
18.4.2 Longitudinal Plan The elevation of inundation in downstream retarding basin is higher than water level in the Nadi River. Therefore, the elevation of the crest of Ring Dike is set considering on the elevation of inundation. The elevation of the crest of Ring Dike is set as E.L. 4.55m in entire section.
18.4.3 Cross-Sectional Plan Either river or land side of slope gradient of Ring Dike are set as 1:3 based on River Embankment Design Criteria in Japan, 2007, River Improvement and Management Division, Water and Disaster Management Bureau, Ministry of Land, Infrastructure, Transport and Tourism. (see 18.1.4(1)a)
Bank width is set as 4.0m based on “Cabinet Order concerning Structural Standards for River Management Facilities, etc. Chapter III Article 21” . (see 18.1.4 (2))
Typical Cross Section is mentioned in Figure 18-23.
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Figure 18-23 Typical Cross Section (Ring Dike)
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18.5 Shortcuts of tributaries Surrounding Dike of Nadi Town mentioned before in Chapter 18.3 cause negative impact (Increasing of Inundation Depth) around the confluence points of Nawaka River and the Malakua River. Shortcuts of tributaries is planned in order to mitigate the negative impact and flood flow can be drained smoothly to downstream by them.
The specifications (Length, Width) of shortcuts are set through hydrological analysis. Details of election of counter measures and flood analysis result are mentioned in “Final Report: VolumeⅡ, Main Report, PartⅠ:Master Plan Sturdy, 7.7.3(3) Counter Measures for Negative Impact caused by the Priority Project”.”.
Plan and typical cross section of shortcuts are described in Figure 18-24 and Figure 18-25.
Figure 18-24 Plan of Shortcuts of Tributaries
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Figure 18-25 Typical Cross Section (Shortcuts of Tributaries)