Technical seminar on Impacts of Infrastructure Development ... › old files ›...
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Technical seminar on Impacts of Technical seminar on Impacts of Infrastructure Development on Infrastructure Development on
Hydrodynamics and Water Quality Hydrodynamics and Water Quality of Deep Bayof Deep Bay
23 April 2005
Challenges for the Protection of Water QualityChallenges for the Protection of Water Qualityin Deep Bayin Deep Bay
K. L. PunDepartment of Civil Engineering, Chu Hai Post Secondary College
Deep Bay
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~5 km
~17 km
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Mangroves and Mudflat at Futian
Sha Chau and Lung Kwu Chau
Marine Park
Chinese White Dolphin Feeding
Ground
Seagrass Bed/Horseshoe Crab Area
Pak Nai SSSI
Tsim Bei Tsui SSSI
Ramsar Site
Mai Po
Seagrass Bed/Horseshoe Crab Area
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The Importance of Deep BayThe Importance of Deep Bay
• A wetland to support many different species of flora and fauna. It comprises:
inter-tidal mudflatsbrackish or freshwater marshesfish and shrimp ponds (“gei wai”)mangrove areasreedbedsseagrass beds oyster bedsstreamsbreeding habitats for birds,horseshoe crabs, dragonflies,amphibians and reptiles
• Deep Bay is a haven for migratory birds Photo courtesy of Ecosystems
Over 60,000 waterbirds in and around the Mai Po and Inner Deep Bay Ramsar Site during winter (WWF)
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• Commercial fishing
trawling
Fishing area (ha)~ 13,350 ha~ 7.3% of total fishing
area in HK
Annual catch of adult fish~ 0.5% of the total catch in HK
(AFD 1998)
• Oyster farming
oyster rafts (HK)
Oyster production (tonnes/year)
•Late 1950’s: 1,200•…•1992: 120•1993: 100•1994: 100•1995: 90•1996: 70•1997: 60•…•2000: 76•…•2004: 210 (?)
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oyster beds (HK)
The Changing Coastline of Deep BayThe Changing Coastline of Deep Bay
The total sea area in Deep Bay is reducing!
1988
1992
1995
20002001Source: Hong Kong Outdoors
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River InflowRiver InflowRivers, streams and nullahs in Deep Bay Water Control Zone:1. River Ganges (GR1)2. River Indus (IN1) 3. River Beas (RB1)4. Fairview Park Nullah
(FVR1)5. Kam Tin River (KT1)6. Yuen Long Creek (YL1)7. Ting Shui Wai Nullan
(TSR1)8. Ha Pak Nai Stream (DB1)9. Tai Shui Hans Stream
(DB2)10.Pak Nai Stream (DB3)11.Sheung Pak Nai Stream
(DB5)12.Ngau Hom Sha Stream
(DB6) 13.Tsang Kok Stream (DB8)
Source: EPD
River Indus• Affected by livestock activities and
unsewered villages• High E. coli: 78,000 count/100mL (2003)• 1990 – 2003: 88% BOD load reduction
River Ganges• Affected by livestock activities and
unsewered villages• High E. coli: 59,000 count/100mL (2003)• 1990 – 2003: 96% BOD load reduction
River Ganges at GR1
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Con
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ratio
n (m
g/L)
BOD5TKNTP
River Indus at IN1
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n (m
g/L)
BOD5TKNTP
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Yuen Long Creek• Affected by livestock activities and
unsewered villages• High E. coli: 1,400,000 count/100mL
(2003)• 1990 – 2003: 92% BOD load reduction
Yuen Long Creek at YL4
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September-97
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Con
cent
ratio
n (m
g/L)
BOD5TKNTP
Kin Tin River• Affected by livestock activities and
unsewered villages, factories• High E. coli: 190,000 count/100mL (2003)• 1990 – 2003: 92% BOD load reduction
Kan Tin River at KT1
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Con
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ratio
n (m
g/L)
BOD5TKNTP
Chi Wan
Shekou
Nan Shan
Da Sha JinxiuZhonghua
Xin Zhou River
Shenzhen River
YuenLongTin Shui Wai
South West Catchment
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Discharge Location BOD kg/d
SS kg/d
Org-N kg/d
NH3-N kg/d
E.coli no./d
TP kg/d
Ortho-P kg/d
TON kg/d
Shenzhen River 97938 77817 6164 6844 2.80E+16 3062 2176 15582 Dasha River 9085 12634 625 645 5.31E+15 197 103 241 Xin Zhou River 22495 27275 1664 2064 1.75E+16 583 328 657 Shekou 9085 12634 625 645 5.31E+15 197 103 241 Jinxiu Zhonghua 60221 61684 4233 5188 3.69E+16 1707 1075 4803 Nanshan 9085 12634 625 645 5.31E+15 197 103 241 Chiwan 31950 23418 2021 2336 8.29E+15 1080 787 5594 Tin Shui Wai 3339 5519 236 156 2.22E+15 75 23 35 Yuen Long 5009 8137 346 226 2.97E+15 104 35 53 Southwest Catchment 651 1071 45 31 4.20E+14 15 5 7
TOTAL 248860 242823 16585 18779 1.12E+17 7216 4738 27455
Pollution loading in Deep Bay (HK + Mainland) – Wet Season
Source: Highways Department, SWC EIA, 2002
Marine Water QualityMarine Water Quality
DM1DM2
DM3
DM4
DM5
Total Nitrogen
0.0
2.0
4.0
6.0
8.0
10.0
12.0
Sep-97 Feb-99 Jun-00 Nov-01 M ar-03 Aug-04
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Concentration (mg
DM 5 DM 3 DM 1
Total Phosphorus
0.0
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0.6
0.8
1.0
1.2
1.4
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Concentration (mg
DM 5 DM 3 DM 1
Dissolved Oxygen
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Concentration (mg
DM 5 DM 3 DM 1
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Marine Water Quality Monitoring Results in Deep Bay WCZ – 2003
Source: EPD
Inner Deep Bay Outer Deep Bay Parameter DM1 DM2 DM3 DM4 DM5
Salinity (ppt)
16.4 18.2 21 23.4 27.1
SS (mg/L)
59.8 42.8 26.1 21.2 11
DO (mg/L)
2.9 3.6 5.3 5.5 5.3
5-day BOD (mg/L)
4.7 4 1.8 1.3 1.1
Unionised Ammonia (mg/L)
0.095 0.105 0.035 0.017 0.009
TIN (mg/L)
5.29 4.23 1.79 1.08 0.7
Total Nitrogen (mg/L)
6.32 5.01 2.07 1.28 0.85
Ortho-phosphate (mg/L)
0.443 0.373 0.139 0.064 0.04
Total Phosphorus (mg/L)
0.61 0.48 0.18 0.1 0.06
E.coli (cfu/100ml)
3800 2200 100 260 540
Sediment QualitySediment Quality
42110270UCEL1265200LCEL
13 - 5546 - 93200 - 300Measured
Arsenic(mg/kg)
Copper(mg/kg)
Zinc(mg/kg)
Parameter /Criteria
Source: Highways Department, SWC EIA, 2002LCEL: Lower Chemical Exceedance LevelUCEL: Upper Chemical Exceedance Level
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Sedimentation in Deep BaySedimentation in Deep Bay• High sediment deposition rate in the region near Shenzhen River
outlet• Sedimentation rate near Mai Po: ~ 25-30mm/year
De-silting the water channel of gei wai 17 at Mai Po in 2003
A Cooling Water Discharge Point in Deep BayA Cooling Water Discharge Point in Deep Bay
CLP Power Plant at Black Point
Pollutants:• Heated water
~6oC or higher• Residual chlorine• Biocides
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Major Infrastructure DevelopmentsMajor Infrastructure Developments
• Shenzhen Western Corridor
• Shenzhen River Regulation project
• Reclamation projects on the Shenzhen side
• A proposed project to pump the seawater from Mirs Bay to flush into the Shenzhen River through a 13 km long pipe with a pumping station at Sha Tau Kok
SWC
Shenzhen RiverReclamation
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Mirs Bay Deep Bay
Salinity
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10152025
303540
4550
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Feb-99Dec-99
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Salin
ity (p
pt
Deep Bay Salinity (DM1)Mirs Bay Salinity (MM1)
pH
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pH
Deep Bay pH (DM1)Mirs Bay pH (MM1)
• Deep Bay is a semi-enclosed water body• tidal flushing is limited• exchange of water is also limited• current speeds in shallow water region are low
• High pollution loads entering Deep Bay• Increase in population in the catchment areas (HK + PRC)• High sediment load from rivers• Polluted sediments in inner bay, e.g. high heavy metal content• High sedimentation rates in inner bay• More infrastructure developments, e.g. reclamation• Two systems implemented in the waters of Deep
Bay/Shenzhen Bay – cross-border water quality issue• +
ChallengesChallenges
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Thank you!Thank you!