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2Risk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
Eng. BANDULA WickramarachchiSenior Coastal Engineer
Coast Conservation DepartmentSri Lanka
S. SivanandarajahSenior Superintendent of Surveys
Survey DepartmentSri Lanka
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Table of ContentsRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
Table of Contents ........................................................................................................................3
1 Introduction .......................................................................................................................... 5
1.1 Agency Collaboration ................................................................................................ 61.1.1 Coast Conservation Department ........................................................................ 6
1.1.2 Survey Department ............................................................................................. 6
1.1.3 Beneficiaries ......................................................................................................... 7
1.2 Global and Regional Initiatives ................................................................................. 7
1.2.1 Intergovernmental Panel on Climate Change (IPCC) ..................................... 8
1.2.2 South Asian Association for Regional Corporation (SAARC) ........................ 8
1.3 Sri Lankan Context .................................................................................................... 8
1.3.1 Coastal Region & Significance ............................................................................ 81.3.2 Coastal Zone Management ................................................................................ 10
1.3.3 Risk Profile ........................................................................................................... 11
2 Objectives ............................................................................................................................. 11
2.1 Planning Reference ..................................................................................................... 11
2.2 Digital Coast ............................................................................................................... 11
2.3 Life Help .................................................................................................................... 12
3 Study Area ........................................................................................................................... 13
3.1 South-west Coast, Galle District ............................................................................. 13
3.2 Coastal Environment ................................................................................................ 14
3.3 Socio-Economy .......................................................................................................... 14
4 Data Used ............................................................................................................................ 15
5 Methodology ....................................................................................................................... 17
5.1 Hazard Assessment ................................................................................................... 18
5.1.1 Observed SL Changes (ko) ................................................................................. 19
5.1.2 SL Rise Projection (hr) ........................................................................................ 19
5.1.3 Sea Level Measurements .................................................................................... 21
5.1.4 Wave Measurements .......................................................................................... 23
5.1.5 Hazard Matrix ................................................................................................... 24
5.1.6 Scenarios............................................................................................................. 26
5.2 Coastal Digital Elevation Model (CDEM) .............................................................27
5.3 Coastal Geodatabase ................................................................................................. 30
6 Results .................................................................................................................................. 34
6.1 Hazard Zones ............................................................................................................ 34
6.2 Vulnerability Analysis .............................................................................................. 37
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Table of ContentsRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
6.2.1 Elements at Risk ................................................................................................. 37
6.3 Risk Assessment ........................................................................................................ 43
6.3.1 Land Inundation ................................................................................................. 43
6.4 Tools ......................................................................................................................... 47
6.4.1 Percentage Area vs Altitude Curve .................................................................. 47
6.4.2 .kml for Google Earth ........................................................................................ 49
6.4.3 3D Visualization ................................................................................................ 49
7 Conclusions and Recommendations .................................................................................. 51
7.1 Data Frames and References ..................................................................................... 51
7.2 Continuation.............................................................................................................. 52
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IntroductionRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
"People in coastal areas will benefit from improved near-real-time data on ocean
conditions, while people everywhere will benefit from better seasonal
predictions resulting from the increased understanding of Earth system
processes enabled by OSTM/Jason 2 sensor measurements."
Dr. Michael Freilich, Director of the Earth Science DivisionNASA's Science Mission Directorate, Washington
Ocean conditions and Earth system processes measurements and monitoring have become to
importance of near-real-time from the space. Sea surface altitude is a significant parameter,
which contributes lot to the analyzing sea level rise trends and its geographical variations.
Consequences of sea level rise studies are still at early stage with high uncertainties and
hence near-real-time accurate data plays a vital role for accurate assessment of the hazard
and impacts. In the present context, the realization of the hazard and impacts on a time scale
could be enhanced the coping capacities of vulnerable elements. Then the human can be pro-
ceed positively with the appropriate adaptation and mitigation measures to minimize the so-
cial, physical, economical and environmental impacts. Consciousness is most important in
long-term, far-reaching solution to sea level rise. It is still uncertain about the capacities of
the human which could be adopted physically against long term sea level rise. But with the
realization of the magnitudes of the risk, policies, practices, legislations, regulations etc
could be formulated or updated towards the safer coastal zones.
Global sea level is intricately linked with Global climate and it is clear that the Global
Warming could raise global sea level. Researchers have proved that earth climate has
warmed about 10 C during the last 100 years. Various measurements and studies have been
indicated an average global rate of sea level rise of 1-2 mm/yr, over the last 100 years. Ther-mal Expansion of global ocean water mass, melting mountain glaciers, melting ice sheets on
Greenland & Antarctic contributed for long term sea level rise. It has been estimated that
the volume of Antarctic and Greenland ice sheets are equivalent to sea level rise of few me-
ters. Although the rate of 2 mm/yr seems to be relatively small, accumulation over years, it
may create devastating impacts to the human, nature and built environment. The coastal re-
sources, which are laid on coastal landforms, reverine areas and coastal wetlands, are vulner-
able for permanent inundation to a depth equivalent to the vertical rise in sea level. Further
the intermittent flooding by storm waves and surges, would penetrate sea water to the in-
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IntroductionRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
land and the beach and cliff erosion will be accelerated. Saltwater penetration into coastal
aquifers and estuaries could contaminate urban water supplies and affect agricultural produc-
tion. The effects of sea level rise are adversely threatening population and economic devel-
opment in the coastal region and the ecosystems.
The project was lead by the Coast Conservation Department with the partnership of Survey
Department of Sri Lanka. The Technical Assistance was from GeoInformatics Center,
Asian Institute of Technology, Bangkok, Thailand and Financial Assistance from Japanese
Aerospace Exploration Agency, Japan.
The Coast Conservation Act No 57 of 1981 vested the administration, control and custody of
the Coastal Zone in the Republic of Sri Lanka and appointed the Director of Coast Conser-
vation, who is responsible for administration and implementation of the provisions of the
act. The Coast Conservation Department is thus the prime agency responsible for coastal is-
sues in Sri Lanka. The Act also conferred the legal responsibility upon the Director, Coast
Conservation to prepare a National Coastal Zone Management Plan (CZMP) and updated
periodically. The 2nd revision of Coastal Zone Management Plane was gazette and activated
in 2006.
The Survey Department of Sri Lanka is the National Surveying and Mapping Organization
and also the national focal point of GIS and Remote Sensing with the representation in the
Global Mapping Project organized by the International Steering Committee for Global
Mapping (ISCGM). The Survey Department is the oldest Government Department in SriLanka established on 2nd August 1800. It serves silently but proudly in all major national de-
velopment schemes as pioneers who step-in first to the sites. The department consists of
technically qualified and dedicated personnel in Surveying and Mapping allied fields exceed-
ing 5000 in number under the leadership of the Surveyor General who is the head of Survey-
ing and Mapping profession and there by legally appointed as the chair person of Sri Lanka
Land Survey Council.
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IntroductionRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
Development of Sri Lankan hazards database with multi hazard risk profile, intended to
provide an overview of the relative vulnerabilities & risk by different hazards in varying lo-
calities, is in progress as a cumulative effort of different professional organizations with theleadership of Disaster Management Center. Disaster Management Canter (DMC) of Sri
Lanka, which holds the National responsibility on Management of all Disasters. Coast Con-
servation Department and Survey Department are key organizations for all the coastal is-
sues and mapping & spatial data issues respectively. The responsibility of Coastal Risk Pro-
file has been assign to the Coast Conservation Department and the mini project has already
been linked.
Sri Lanka is now progressing for the Second National Communication on Climatic Changed
of UNFCC in 2010. The Mini Project Results would be discussed in depth at the Working
Groups of Technology Transfer, Adaptation and Mitigation. Further, South Asian Associa-
tion for Regional Corporation (SAARC) Coastal Zone Management Center has identified
Impact of Climatic Change on Coastal Zone as one area needs to be addressed regionally. It
has been included in the annual plans since 2008.
The results of the study are benefited for the national planning organizations too;
Urban Development AuthorityLocal Administration AuthoritiesNational Planning DepartmentAll the infrastructure development agencies, etc.
Tools and visualizations are much important in the public awareness programs. At present
context, more researches shall be promoted for adding more reliability of the results. The
study could be used as the base for formulation of research areas.
The climatic change and sea level rise is a complex global issue, and the monitoring, re-
search, investigations and developments should be shared by each Nation and should flow
through Local, Regional to Global.
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IntroductionRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
Intergovernmental Panel on Climate Change (IPCC) was established in 1988 by World Me-
teorological Organization (WMO) and United Nations Environment Program (UNEP).
The main aim of IPCC is to shearing information on observed and projected impacts ofClimate Change and updated scientific findings to all nations to explore the alternatives for
preparedness, adaptation and mitigation.
IPCC reports, published at regular intervals, are available for reference for policy makers,
researchers, experts etc. On the findings of the first IPCC Assessment Report of 1990, Unit-
ed Nations Framework Convention on Climate Change (UNFCCC) was established at the
Rio de Janeiro Summit in 1992 and is in force since 1994. It provides the overall policy
framework for addressing the climate change issue. Kyoto Protocol was negotiated in 1997 as
an output of second IPCC Second Assessment Report of 1995. The Third Assessment Report
was released in 2001 with further information.
SAARC secretariat has already initiated few programs on Climatic Change with the share
of the Member States. Disaster Management & Environmental chapters are working on rel-
evant disciplines through researches, projects and programs. SAARC coastal zone manage-
ment centre has initiated program for the assessment of impact on the coastal resources due
to climatic change with the proficiencies of their Member States.
Sri Lanka is an island nation in South Asia located about 31 kilometers off the southern coast
of India, laying between Latitude 50
55 90
51 and Longitude 790
42 810
52. The islandlies in the Indian Ocean, to the southwest of the Bay of Bengal and to the southeast of the
Arabian Sea. It is separated from the Indian subcontinent by the Gulf of Mannar and the
Palk Strait. The tear drop shaped island consists mostly of flat coastal plains, with moun-
tains rising only in the south-central part.
The total length of the coastline is about 1,650 km. The Maritime claims are territorial sea 12
nm; contiguous zone 24 nm; exclusive economic zone 200 nm; continental shelf 200 nm or tothe edge of the continental margin. The land area is about 65,610 sq km and the maximum
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IntroductionRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
length and width of the island is 435 km and 240 km respectively. The aspect ratio of the is-
land is 0.552 and circularity 0.300.
The coastal region consists of a series of lagoons, marshes, sandbars, dunes, coral reefs and113 islands. Beyond Dondra, which is the southernmost end of the island, the vast stretch of
ocean extends to the Antarctica landmass, which results all the waves generated in the
southern open sea travels to the southern coast of the island with heavy wave energy. Hence
the southwest monsoon (June October) is significant in wave climate than the northeast
monsoon (December March), which is effective to the north and east coast of Island.
In the administrative setup Island is governed in 9 provinces, and 5 provinces are havingcoastal boundaries. Further 14 districts out of 25 and 77 Divisional Secretary Divisions
(DSD) out of 324 are with coastal boundaries. As per the coast conservation act No 57, gen-
erally the coastal zone on land area has been defined as 300m belt from the coast line. But for
the research and studies it is much reasonable to consider at least up to the Divisional Secre-
tariat Divisions having coastal boundaries. The DSD having coastal boundaries are covered
22% of the total land mass of the Island.
Despite the smallness, Sri Lanka has a wide range of geographic features and is rich in natu-
ral beauty with tropical forests, beaches and landscapes, as well as its rich cultural heritage,
make it a world famous tourist destination. Coastal truism is major economic sector in the
country. Because of its location in the path of major sea routes, Sri Lanka is a strategic naval
link between West Asia and South East. The fisheries sector contributes nearly 3% to the
national economy. This factorizes more or less to maritime socio-economy in the country.
Coastal regions, areas are home to a large and growing proportion of the world's population.
The situation is particularly acute in Sri Lanka as a developing country. Today, approxi-
mately 4.6 million people - about 25% of the Island's population - live within the coastal re-
gion. The high concentration of people in coastal regions produce many economic benefits,
including improved transportation links, industrial and urban development, revenue from
tourism, and food production. According to the Coastal Economic Study 2006, Sri Lanka
done by Coast Conservation Department, 44% of the National GDP is from the Coastal Re-
gion, i.e. from 22% of the total lands of Island.
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IntroductionRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
With the majority of the population located in the coastal zone and the main population
growth for the coming decades predicted to be in coastal areas, the need to estimate potential
risk caused by sea-level rise is acute. Lack of detailed data, in terms of both scale and long-
term observation, limits the assessment of these impacts.
Researches on relative risks and impacts of sea level rise on specific localities are still at early
stages. The present study utilized principles drawn from presently available coastal-behavior
models to identify physical impacts of sea-level rise on erodible open-ocean coasts and deep-
ly-embayed shorelines, including lagoons & estuaries. Information on consequences of sea
level rise, have been added-on to the spatial data layers with the temporal delineations. De-
scriptive impacts, which illustrated spatially, in diverse formats such as hard copy maps, dig-
ital database, animations, visualizations etc, have been generated for the different user seg-
ments in their proficient languages.
Starting from the early 1970s different management concepts were applied for the manage-
ment of coastal zone. Before 1970, with the realization of the coastal erosion, Coast Protec-
tion works were undertaken by a unit of Coastal Works in the Sri Lanka Ports Authority.
In 1970s, it was identified the necessity of Conservation of Coastal Resources. The concepts
were mainly on conservation and it was the 1
st
Generation of the Coastal Management in theisland. 2nd Generation was commenced with the concepts of Sustainable Coastal Develop-
ments and the Coastal Works unit was upgraded as the Coast Conservation Department
(CCD). To overcome the user conflicts, Coastal Zone Management was introduced in
1980s. With the degradation of coastal resources in 1990s, more concerns were on the
Coastal Resource Management. 3rd Generation has begun with the new millennium. In
2000s, Shoreline Management concepts were adopted by eliminating the coast protection
practices. With the Tsunami Disaster in 2004, Coastal Disaster Management was activated.
New era in the Disaster Management in Sri Lanka was begun with the 2004 Tsunami Disas-
ter. Ministry of Disaster Management and Disaster Management Center (DMC) were es-
tablished in working with all the disaster maters in the island. Since the DMC involve
mainly in the coordination with all the expert agencies for the management of disasters in
Sri Lanka.
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ObjectivesRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
The Risk Profile is explained as the Hazard Zoning Maps for hazards affecting the country,
with overlays of vulnerable elements at risk and a description of existing coping capacity.
The study was mainly aimed to the element of Coastal Risk Profile in the context of SeaLevel Rise. But the study will be made the provision towards Multi Hazards Risk Profile,
not only the coastal hazards but also all the possible major hazards.
Providing an overview of the vulnerabilities of the coastal resources to the sea level rise is
highly important in planning & developing the coastal zone. The purposes of a Risk Profile
are to depict risks spatially on time series; to guide the formulation or updating of Coastal
Zone Management and Disaster Management policies, development of mitigation, adapta-
tion in preparedness plans, and allocation of resources for disaster risk reduction.
In Sri Lanka different administrative layers are in active with their own disciplines, geo-
graphic boundaries and development goals. For the continuing sustainability, the projects
and programs should be examined in means of economic, social, environmental and safety.
If the planners are equipped with the Disaster Management (DM) guidance, which has por-
trayed the spatial distribution of possible hazards and impacts with the temporal projections,
development goals could be achieved through high factor of safety at reduced disaster cost.
Deriving enhanced tools for guiding the planners were the main stream of this project.
To help coastal managers, making and prioritizing decisions on coastal management, spatial
database was compiled with fairly accessible data. With the quick access to the coastal geo-
database, reports, maps, and data tables, as well as evaluation and comparison of alternatives
are made straightforward. The currently available software provides facilities for critical
analyses with high reliability. Digital data could be web hosted for the easy access. Availa-
bility & reliability of data improve the confidence levels of predictions and forecasts too.
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ObjectivesRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
When considering the nature of the sea level rise hazard, improvement of the awareness and
education is vital important. Easy-to-understand tools and visualizations in different for-
mats could make clear the situation for the public in different professions. Shearing infor-
mation with the researchers and students were able to continue the research and studies to-
wards better results.
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Study AreaRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
The location of the island in the Indian Ocean has greatly influenced on the coastal zone.
Southern & south-west coast were severely eroded for the last centuries and Coast Protec-
tions have been undertaken to protect the land from the sea erosion since 1970s. Tsunami,
Low frequent high intensity, coastal disaster was experienced the island in December 2004.
Since most of the coastal lands are flat plains, the sea level rise may tend to permanently or
intermittently inundate, and increase the coastal erosion.
South-west coast is entirely covered by the Galle Administrative District. The Coastal
length of the Galle district is about 95 kilometers and the total population is around 2.3 mil-
lion. Galle city is the capital of Southern Province and the city has been developed around
the Galle Bay.
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Data UsedRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
Admin Boundaries
Roads
Hydro
Land Use/Land Cover
Building Foot Prints
Contour & Spot Heights
Digital Elevation Model
Date of Acquisition 2002
PRISM (Date of Acquisi-
tion 2007/03/11)
PALSAR (Date of Acqisi-
tion 2008/03/03)
Quickbird Images
Population
Age
Education
Employment
Hourly from 2004 to 2008,
at Colombo
From 1989 to 1995 off Galle
deep sea (75m depth)
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Data UsedRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
Harbours
Landing sites
Anchorages
Scenic sites
Madel beach sites
Break water
Revetment
Sea wall
Bolder dump
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MethodologyRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
Hazard Assessment
Sea Level Rise
Sea Level Measurements
IPCC Reports
Literature Review
Wave Dynamics
PermanentInundation
Seasonal SurgeIncreased Sea
Erosion
Vulnerability Analysis
Hazard
Zones
Built Environment Profile
Natural Profile
Regional Studies
LiDAR DGM & Topography
Human Profile
Social Physical
Vulnerability flows throughgenerations and require
defining vulnerabilityprojections & Vu of practices,
policies, legislations etc.
Risk Assesment
Elements
atRisk
Statistical Discriptive
Reporting
Tabulation
Graphically
Risk
P
rofile
Tools
Coastal Processes
Economic Environmental
Coastal GeoDatabase
Visualizations
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MethodologyRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
People and resources located within the risk zones are vulnerable for the hazards. The vul-
nerabilities are functions of their individual coping capacities to the impacts of hazard.
Therefore the main emphasis of the study was given to describe the temporally projected
impacts of the SLR at spatial scales with their significance, which act on Nature, Human,
and Built Environment in the coastal region.
Since the topic of Sea Level Rise is discussed with uncertainties & for the simplicity of anal-
ysis at the early stage of the study, SLR was considered as an autonomous process. But in
reality the SLR studies has to be integrated with many other processes linked to coastal
zone. Further there are many factors for the sea level variations, but some scenarios are
highly uncertain. No literature could be found on some processes.
12 24 hrs Considered
433 days
Hours - months Chapter on multi risk
Hours - months
Hours - months
Days - weeks
6 months
Days Chapter on multi risk
Months
Second - hours Considered
Hours Chapter on multi risk
Minutes - years
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MethodologyRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
With the non-availability of data or literature on some of the above causes, and some are
considered as separate chapters in the multi hazard risk profile, Sea Level Rise added only on
the wave dynamics and tidal waves were considered as major component for sea level varia-
tions. However there would be an added intensity on sea level rise due to minority factors,
discussed on the above table, together with varying wave dynamics with the climate change.
Further the decaying factors of tides and waves propagating in to inland, which needs nu-
merical model for the analysis, were not considered. It results the inputs are at high-end for
the analysis, and hence the minority factors were eliminated.
Tide 12hrs 19 yrs / cyclic ht
Wave Minutes hours intermittent hw
Sea Level Rise Years acceleratin ko + hr
h
Wave climate variation Due to climate chan e f
Factors in above table Uncertain k
According to the IPCC report 2007, the Global average sea level has risen at an average rate
of 1.8 [1.3 to 2.3] mm per year over 1961 to 2003. But the average rate has increased to 3.1 [2.4 to
3.8] mm per year from 1993 to 2003. Since the Mean Sea Level for Sri Lanka was established
in 1920s the sea level rise since then should be added for the analysis. But the observat ions
are available since 1961, and hence constant value for the period from 1961 to 1999 was consid-
ered for the development of scenarios.
The IPCC report has provided the model-based projections of global average sea level rise at
the end of the 21st century (2090-2099). Basically the models are based on the rate of econom-
ic development and the population growth.
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MethodologyRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
Further it has reported that the projections include a contribution due to increased ice flow
from Greenland and Antarctica at the rates observed for 1993-2003. But if this contribution
grows linearly with global average temperature change, the upper ranges of sea level rise for
SRES scenarios would increase by 0.1 to 0.2 m. The projected sea level rise due to increasing
ice flow affixed into the scenarios.
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MethodologyRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
For determining the reference heights of increased accumulated water levels, the tidal varia-
tions were considered. Tidal measurements done at Colombo by National Aquatic Research
Agency (NARA) were used.
IPCC Special Report on Emissions Scenarios (SRES, 2000)
Considering alternative development pathways, covering a wide range of demographic, eco-
nomic and technological driving forces and resulting GHG emissions, the scenarios aregrouped in to four families A1, A2, B1 and B2.
A1 World of very rapid economic growth, a global population that peaks in mid-century and rapid introduction of new and more efficient technologies.
A1FI - Fossil intensive A1T - Non-fossil energy resources A1B - Balance across all sources
B1 - Convergent world with the same global population as A1, but with more rapidchanges in economic structures toward a service and information economy
B2 World with intermediate population and economic growth, emphasizing localsolutions to economic, social, and environmental sustainabilityA2 - Heterogeneous world with high population growth, slow economic develop-
ment and slow technological change
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MethodologyRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
Even though the study was done for the south-west coast, Colombo measurements were ap-
plied. Due to the varying locality, the difference is mostly the phase of the tide, but for the
study it was used only the magnitude.
Using the event probabilistic analysis it was determine the tidal heights with annual,
monthly, and daily return period. In the development of scenarios it was considered that the
risk levels are increased with the increasing likeliness. Therefore the daily return tide were
considered as more eternal enough to consider as permanent water, monthly return moder-
ate and yearly return intermittent with less harm to the human life and other resources.
Since the tidal behavior is cyclic from hours to 19 years, for better result the probability shall
be analyzed on the time series.
The measurements have been reference to a control of height 0.935 m above mean sea level
(MSL), the measurements were reduced to the MSL.
1.862 0.927
1.806 0.871
1.591 0.656
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MethodologyRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
For estimation of the increased accumulated water levels and wave run-up for the hazard
analysis on permanent inundation, surge overtopping and increased coastal erosion calcula-
tions, wave measurements done by CCD at Galle offshore in 75m depth were used. Similar-ly as tidal analysis the event probabilities were done for determining the wave heights with
annual, monthly and daily return periods.
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MethodologyRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
Since the waves were measured at 75 m depth, it was transformed to shallow water on
MIKE 21 NSW model. But due to the unavailability of near shore bathymetry it was trans-
formed to the 7m depth and hence the usages in the analysis were meaningless.
5.21 4.45 237 8.0
3.66 3.06 244 6.5
2.50 1.89 232 5.5
The hazard matrix was developed for Hierarchical Analysis (HA) of different risk factors.
Wave dynamics Tidal climate Sea level rise Ice flows
The probability of the events and their intensities were evaluated for the HA. The hazard
matrix was eliminated the complexity of evaluating scenarios with different risk levels. The
probability of daily, monthly and yearly return factors were very clear. As per the IPCC re-
port and few other studies, the SLR and Ice flow probabilities would be increase with the de-
creasing intensities.
For the understanding of the intensities of factors of risks, both the water retention periods
and water column heights were considered. SLR and ice flows are permanent while wave
and tides are with varying retention times. Factors having daily return period have been
considered as permanent and factors with yearly return period make lesser impacts. Factors
with monthly return period tend to make considerable impacts. The criterion was applied in
developing the hazard matrix making justifications to each and every factor.
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MethodologyRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
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MethodologyRisk Profile on Sea Level Rise for Coastal Zone Management
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For describing the hazard in varying levels two scenarios were developed on the varying risk
levels of factors considered in the hazard matrix. Since the Mean Sea Level for Sri Lanka
was established in 1920s, sea level rice correction was considered as constant value based onthe observed global average rate of SLR, for the both scenario analysis. But the SLR observa-
tions have been available only for the period from 1961 to 2003 and hence it was only applied.
The Scenario End 2100 were based on the probable varying heights of each variables at year
2100. Even though the worst case has accumulated to the highest sea level, it has the least
probabilities, but least case has the highest probabilities. Hence the least case was considered
as the high hazard, worst case as low hazard and average case as moderate hazard.
1961 to 1999
38 yrs @ 1.8 mm
Model-based max-
imum
Yearly Return
Tidal Wave
Predicted Maxi-
mum
1961 to 1999
38 yrs @ 1.8 mm
Model-based Av-
erage
Monthly Return
Tidal WavePredicted Average
1961 to 1999
38 yrs @ 1.8 mm
Model-based Min-
imum
Daily Return
Tidal Wave
Predicted Mini-
mum
Scenario - Progressive examine the increasing impacts on time series with the progressing of
sea level rice. It was benchmarked at 2025, 2050 and 2100. Year 2000 value was determined for
the field verification at courser accuracy. Monthly tidal wave height was used for the scenar-
io considering its higher impacts at considerable frequency.
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MethodologyRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
The strength of the study is the LiDAR coverage of the coastal belt of the study area. Since
the sea level rice is in the range of sub meter level the accuracy of the DEM should be at a
higher degree. Hence the LiDAR DEM accuracy was checked by comparing a DEM generat-
ed using spot heights, which were taken at a nearly flat ground in Galle city, reference to 1 st
order control point. It was found that the mean error is around 7 cm.
1961 to 1999
38 yrs @ 1.8 mm
Daily Return
Tidal Wave
1961 to 1999
38 yrs @ 1.8 mm
Model-based
Quarter(Max)
Monthly Return
Tidal Wave
Predicted Quarter
(Max)
1961 to 1999
38 yrs @ 1.8 mm
Model-based Half
(Max)
Monthly Return
Tidal Wave
Predicted Half
(Max)
1961 to 1999
38 yrs @ 1.8 mm
Model-based
(Max)
Monthly Return
Tidal WavePredicted (Max)
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MethodologyRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
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MethodologyRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
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MethodologyRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
But the LiDAR coverage was limited to nearly 02 km from the coastline. Trial studies
showed that the permanent inundations are around inland water bodies and extend beyond
02 km. Then the LiDAR DEM merged with the DEM generated for the inland using con-
tours and spot heights of survey department maps.
The Coastal GeoDatbase (CGDB) was compiled for the identification of the elements at
risk and further it will be benefited coastal mangers in decision making and analysis. CGDB
was compiled on three major categories.
1. Natural2. Built Environment3. Human
All the resources within the coastal zone have been categorized in to one of the above cate-
gory.
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MethodologyRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
Natural
Hydo Poly
Land Cover Poly
Lagoon
Estuaries
Lake
Rivers
Sea
Water Log
Salt pan
Hydro Line
Streams
Barren Land
Forest
Grass Land
RocksSand
Marsh
Mangroove
Scrub
Terrain Line
Indexed Contours
Inter Contours
Terrain Point
Spot Height
Trig Point
Shoreline Poly
Off Shore Islands
Rocky Outcrops
Shoreline Line
Headlands
Major Cells
Minor Cells
Beach Slopes
Shore Alignments
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MethodologyRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
Human
Population
Age
Education
Employment
Gender
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ResultsRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
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ResultsRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
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ResultsRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
Vulnerabilities of resources in the coastal zone were analyzed in four sectors.
1. Social2. Economic3. Physical4. Environmental
The features in the CGDB were reclassified in the different data layers on the vulnerability
themes of Social, Economical, Physical and Environmental. Laying hazard zones over thevulnerability themes, the elements at risk were identified and displayed on maps.
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ResultsRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
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ResultsRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
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ResultsRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
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ResultsRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
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ResultsRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
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ResultsRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
Assessing the risk of land inun-
dation in each DS divisions, the
area to be inundated were esti-
mated at different scenarios.
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ResultsRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
The building features were
reclassified in to social, eco-
nomic and physical themes for
analyzing their vulnerabilities.
Since it is unreasonable to ana-
lyze the risk at 2100 for exist-
ing buildings, 2050 hazard lay-
er was used and elements atrisk in percentage of existing
were determined.
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ResultsRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
1,005.77
7.16
10.53
1,643.22
105.58
210.94
13.0
1847.1
2.9
4.393.10
7.03
1,968.69
610.34
The length of different
types of roads at risk were
determined and displayed in
stacked bar chart.
Land cover clas-
sified under theNatural Re-
source Profile
and Land use
under the Built
Environment.
Land use reclas-
sified in to Eco-
nomic and So-cial for analyz-
ing the vulnera-
bilities. Vulner-
able extent of
lands were esti-
mated and tabu-
lated for the ref-
erence.
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ResultsRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
Vulnerabilities have been
compared within the same
classes using Pie charts.
The Pie charts could be
use to illustrate compara-
tively the vulnerabilities
of different classes of So-
cial, Economic and Envi-
ronmental.
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ResultsRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
Percentage area vs altitude curves, which will be useful understanding risk of land inunda-
tion with the increasing sea water level, have been developed for each Divisional Secretariat
Divisions.
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ResultsRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
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ResultsRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
The hazard level layers were exported to .Kml for visualizing on the Google Earth. The .kml
could be uploaded to the web and those who have internet access could assess the risk indi-
vidually by a mouse click on the web.
It could be used for the verification of the results too. Since the GeoDatabase were compiled
on UTM projection, it was accurately position on the Google.
3D visualizations are much effective in public awareness on the impacts of SLR. Using the
updated GIS software it was captured 3D movie clip to illustrate the inundation zones.
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ResultsRisk Profile on Sea Level Rise for Coastal Zone Management
Galle District, Sri Lanka
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