slr report

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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

[email protected]

S. SivanandarajahSenior Superintendent of Surveys

Survey DepartmentSri Lanka

[email protected]
mailto:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]


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Table of ContentsRisk Profile on Sea Level Rise for Coastal Zone Management


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


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


"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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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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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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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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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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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


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


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


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


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


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


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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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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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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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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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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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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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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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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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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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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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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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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Human

Population

Age

Education

Employment

Gender


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ResultsRisk Profile on Sea Level Rise for Coastal Zone Management



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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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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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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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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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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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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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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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slr report

Documents