Welcome to the Presentation on - NCCARF · Welcome to the Presentation on Vulnerability of Coastal...
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Welcome to the Presentation on Vulnerability of Coastal Island and Adaptation Measures for Cyclonic Storm Surge and Climate Change in the Coastal Area of Bangladesh Md. Mobassarul Hasan Associate Specialist/ Coastal Hydraulic Engineer Institute of Water Modelling Bangladesh
Transcript of Welcome to the Presentation on - NCCARF · Welcome to the Presentation on Vulnerability of Coastal...
Welcome to the Presentation
on
Vulnerability of Coastal Island and Adaptation Measures for Cyclonic Storm Surge and Climate Change in the Coastal
Area of Bangladesh
Md. Mobassarul Hasan Associate Specialist/
Coastal Hydraulic Engineer Institute of Water Modelling
Bangladesh
Floods
Droughts
Erosion
Salinity intrusion
Cyclone and storm surge
Geographical Setting of Bangladesh
DEM (Digital elevation Model) of Coastal Area of Bangladesh
62% area is lower than 3 mPWD
86% area is lower than 5 mPWD
Vast river network
Coastal Area of Bangladesh
Total Districts 19 out of 64
Total population 35.1 million, 28 % of total population
Total area 47,201 km2, 743 people/km2
Total coastal polders 123, 5107 km embankment
Height of Coastal Embankment
3 – 4 m
4 – 5 m
5 – 6 m 6 – 7 m
Past Cyclones Attacked Bangladesh Coast
CS 62-88 km/hr
SCS 89-117 km/hr
During last 125 years 43 severe cyclones hit the coastal belt
Since 60s 29 severe cyclones occurred, while most severe ones in 1970, 1991 & 2007
Past cyclones attacked Bangladesh coast
Study Area
Sea Level Rise Consideration
IPCC-Inter-Governmental Panel on Climate Change - jointly organized by UNEP and WMO in 1988 to assess
the scientific and technical literature on climate change, the potential impacts of change in climate and response strategies to climate change
4th IPCC – 2007: Global prediction 18 – 59 cm sea level rise (1990-2100)
59 cm and 1 m SLRs have been selected for this Study
According to the Synthesis Report of Copenhagen Summit on March 2009 maximum SLR will be 1±0.5m by 2100
Selection of Cyclonic Track
Track of SIDR has been selected for the Study
Track Selection
Track 3
Track 2
Track 1
Track 3
Track 2
Track 1
Three different tracks have been selected for each Island
Option Selection
1. Track 1 + SIDR Cyclone + SLR 59 cm + High Tide
2. Track 2 + SIDR Cyclone + SLR 59 cm + High Tide
3. Track 3 + SIDR Cyclone + SLR 59 cm + High Tide
4. Track 1 + SIDR Cyclone + SLR 1 m + High Tide
5. Track 2 + SIDR Cyclone + SLR 1 m + High Tide
6. Track 3 + SIDR Cyclone + SLR 1 m + High Tide
Track 3
Track 2
Track 1
Track 3
Track 2
Track 1
Mathematical Model
MIKE 21 : Two-dimensional modelling system for estuaries, coastal water and seas.
Hydrodynamic Model
Cyclonic Model
Combination of these two is known as Storm Surge Model
Bed Level, mPWD
Bathymetry of Bay of Bengal Model
India Myanmar
Bangladesh
Bay of Bengal
Vishakahpatnam Gwa Bay
Chandpur
Tidal Fluctuation in the Meghna Estuary
Result of Cyclone Model
Result of Storm Surge Model
Hiron Point
Measured storm surge
Model computed storm surge
Verification of model for SIDR: Hiron Point
Hiron Point
Variation of Water Level due to SIDR at Hiron Point
Measured surge, m
Expected tide
Tidal condition during landfall
Hiron Point
Development of Local Models
India
Vishakhapatnam
Gwa Bay
Chandpur India
India
Bay of Bengal
Coarse Model
Coarse Model: 5400m X 5400 m
Intermediate Model
Intermediate Model: 1800m X 1800 m
Long: 89o58/16.32//
Lat: 21o20/21.48//
Fine Model
Fine Model
Fine Model: 600m X 600 m
Local Model 1: 200m X 200 m Local Model 1 Local Model 2: 66.66 m X 66.66 m
Local Model 2
Boundary Condition
Coarse model (5400m grid model)
Intermediate model (1800m grid model)
Fine model (600m grid model)
Local model (200m grid model)
Local model (66.66m grid model)
South Boundary
North Boundary
Generate Boundary for 1800m grid model
Generate Boundary for 600m grid model
Generate Boundary for 200m grid model
Generate Boundary for 66.66m grid model
South Boundary
North Boundary
Coarse Model Area
(a) (b) (c)
Maximum Water level in Different Track
SIDR Cyclone + SLR 59 cm + High Tide
Sandwip Island
Track 1 Track 2 Track 3
Mean Embankment Height 5.5 mPWD
Mean Land Level 3.8 mPWD
Maximum Water level in Different Track
Track 3
Track 2
Track 1
Sandwip Island
SIDR Cyclone + SLR 59 cm + High Tide
Maximum Water level in Different Options
Track 3
Track 2
Track 1
Options Maximum Water
Level (m PWD)
Track 1 + SIDR Cyclone + SLR 59 cm + High Tide 9.1
Track 2 + SIDR Cyclone + SLR 59 cm + High Tide 9.65
Track 3 + SIDR Cyclone + SLR 59 cm + High Tide 10.3
Track 1 + SIDR Cyclone + SLR 1 m+ High Tide 9.4
Track 2 + SIDR Cyclone + SLR 1 m+ High Tide 9.96
Track 3 + SIDR Cyclone + SLR 1 m + High Tide 10.62
Sandwip Island
(a) (b) (c)
Hatiya Island
Maximum Water level in Different Track
SIDR Cyclone + SLR 59 cm + High Tide
Maximum Water level in Different Track
Track 3
Track 2
Track 1
Mean Polder Height 6 mPWD
Mean Land Level 1.8 mPWD
Track 1 Track 2 Track 3
Hatiya Island
SIDR Cyclone + SLR 59 cm + High Tide
Maximum Water level in Different Options
Options Maximum Water
Level (m PWD)
Track 1 + SIDR Cyclone + SLR 59 cm + High Tide 10.52
Track 2 + SIDR Cyclone + SLR 59 cm + High Tide 10.98
Track 3 + SIDR Cyclone + SLR 59 cm + High Tide 11.0
Track 1 + SIDR Cyclone + SLR 1 m+ High Tide 10.84
Track 2 + SIDR Cyclone + SLR 1 m+ High Tide 11.3
Track 3 + SIDR Cyclone + SLR 1 m+ High Tide 11.3
Hatiya Island
Track 3
Track 2
Track 1
SIDR Cyclone + SLR 59 cm + High Tide
Impact Increased of Wind Speed
According to 4th IPCC Report temperature will increase by 2oC to 4oC in the year 2100
Temperature increase
Corresponding wind speed
increase
2oC 10%
4oC 20%
If the same cyclone comes with 10% increased wind speed then surge height may increase by 0.9 m for both the island
Adaptation Options
Early Warning System
Cyclone Shelter
Coastal Embankments
Afforestation
Sandwip
Point 1 Width of Mangrove
Water Level
(mPWD)
Current Speed (m/s)
Reduction in Surge
Height (cm)
Reduction in Current
Speed (m/s)
Point 1
Without Mangrove 10.01 2.35 - -
200m 9.88 0.88 13 1.47
400m 9.86 0.85 15 1.50
600m 9.82 0.84 20 1.51
Benefit of Afforestation
Cyclone Shelter
Location of Cyclone Shelter
Cyclone Shelter
We have 2500 shelters right
now
We need 5000 shelters according to our population
Coastal Embankment
Embankment Crest Level 5.5 mPWD (existing)
Land Level 3.8 mPWD
5.32 m
Embankment Crest Level 10.82 mPWD (required)
7.02 m
Sandwip Island
SIDR Cyclone + SLR 59 cm + High Tide + Free Board
Coastal Embankment
Embankment Crest Level 6.0 mPWD (existing)
Land Level 1.8 mPWD
5.5 m
Embankment Crest Level 11.5 mPWD (required)
9.7 m
Hatiya Island
Early Warning System
Cyclone 1991
Cyclone 2007 (SIDR)
Warning System
Not applied applied
Max Wind Speed
225 km/hr 240 km/hr
Death Toll 138,882 5,000
Conclusions
The impact of cyclonic storm surge and climate change on coastal livelihood and food security is significant. It is important to revisit the planning and design of existing coastal infrastructure and to rehabilitate these structures to make it climate and cyclone resilient.
The risk of climate change and cyclonic storm surge is to be considered for future planning and design of coastal structure.
Conclusions
Proper adaptation measures both structural and non-structural are to be planned in order to find a climate and cyclone resilient coastal environment for food security and livelihood security.
