1. NOVEMBER 28, 2016
COASTAL EROSION RISK ANALYSIS
Liton Chandra Mazumder Michael G. Tadesse Mohamed H.M. Elamen
BHOLA DISTRICT, BANGLADESH

2. Outline
1. Introduction
2. Study Area
3. Objective
4. Methodology
5. Results & analysis
6. Conclusions
7. Recommendation
8. References

3. Introduction
● With half of the world’s population living near the coast, an immense threat is posed by coastal
hazards to life and health, livelihood, and the economy.
● Coastal Erosion: wearing away of material from the coastal profile due to imbalance in the supply
and export of material from a certain section.
● Slow, silent disaster (Makenro, 2000)
● Adversely affects ecosystem, navigation, agriculture development, and drainage system
● 1 million people displaced and 9000 hectares of land are inundated annually in Bangladesh

4. Study area
● Area & Population
○ 3403.48 sq.km
○ 1.8 million
● Economy
○ Fishing (60%),
○ agriculture(30%)
○ other (10%)
● Natural Charact.
○ 2 -3 meters M.S.L
○ Annual rainfall is 2360 mm (Banglapedia) Bhola District, Bangladesh

5. Bhola District
● largest island in the coastline
● Emerged in the Meghna estuary 800 years ago
● Situated at the mouth of Meghna River
○ Exposed to cyclones and storms
● 90 km long and 20 km wide
● 6 Upazilas (Sub-Districts) chosen for the study
● Major sediment conduits through the Meghna
estuary raise the land whereas simultaneous strong
tidal waves accounts for land erosion.
● Squeezed to 3400 km2 (2004) from 6400 km2
(1960)

6. Motivation
Dynamic Delta
Consequential
cascading
impacts
Families
lose their
agricultural land

7. Potential Factors of Erosion
○ Large River Discharge through the GBM river system
○ Strong tidal action (Long wave action)-
○ Storm surges (Devastating action of major cyclones)
○ Accelerated Sea level rise(SLR)
○ Longshore current
○ Anthropogenic activities

8. 1. Large River Discharge through the GBM river system
● (GBM) is drained into the Bay of Bengal via the
Meghna Estuary
● Discharge is 15 times during monsoon period
compared to dry season
● 20,000 m3/s dry season Vs 100,000 m3/s monsoon
season
● Max 160,000m3/s in wet season.

9. 2. Tidal Range at different locations
Location Name of the channel Season MaxWL(mPWD) Min(mPWD) Max Tidal
Range(m)
Daulotkhan RB of West Shahabazpur Channel Dry 2.4 -1.02 3.4
Tazumuddin RB of West Shahabazpur Channel Dry
Monsoon
1.68
3.49
-1
-0.41
2.68
3.89
Char fession Channel between Charfession and
Monpura
Dry
Monsoon
1.3
2.8
-0.9
-0.43
2.14
3.2

10. 3. Cyclones in Bangladesh
• Cyclones hit the coastal regions of Bangladesh almost every year, in early summer (April‐May) or
late rainy season (October‐November).
• On average, a severe cyclone strikes Bangladesh every three years (GoB, 2009).
• Between 1877 and 1995 Bangladesh was hit by 154 cyclones (including 43 severe cyclonic storms,
43 cyclonic storms, 68 tropical depressions)
• Recently since 1995, five severe cyclones hit coast of Bangladesh coast in May 1997, September
1997, May 1998, November 2007 and May 2009.

11. OBJECTIVE
Identify and rank
hotspot areas in order
to define priorities and
support disaster
reduction plans by
calculating coastal
indexes for hazards
and the associated
exposure.

12. METHODOLOGY

13. Problem identification
Data Collection
F
F
F
F
F
F
F
F
F
F
F
f
Exposure
G
G
G
G
G
G
G
G
G
f
Hazard
V
V
V
V
V
V
V
V
V
v
Coastline
Digitization
Defining
Buffer Zone
Population Data
Population
indicator
map
Busi.settings
indicator
map
Landuse
indicator
map
Transport
indicator
map
Business
setting
digitizing
Supervised
Land use
classification
Road Asset
dataHazard
Map
Exposure
Map
Risk Map
Adaptation
strategies
Risk analysis

14. Data collection Landsat Satellite image (1978 -2015)
Supervised classification of land use
Population density of upazilas [Sub-District]
Transportation (Road Asset)
Business settings
EXPOSUREHAZARD

15. Imagery processing
Landsat (L1-5, L 4-5, L7, L8)
QGIS 2.18 & ArcMAP 10.2
Google Earth Pro 7.1.7.2606
Comparison of LANDSAT images
from 1978 to 2015

16. Coastline Change [1978-2015]
1989 1999 2008 20151978

17. Cross Sections
19 sections were selected to assess
the erosion rate along the coast

18. Defining Buffer Zone
Max Erosion rate = 132 m/Year
Projected for 60 years ~ 8Km
iPop iLU
iBus iTrn

19. Population Indicator
Upazila
Population
Density
(P/Km2)
Bhola Sadar 1040
Burhanuddin 730
Charfassion 309
Daulatkhan 480
Lalmohan 640
Tazumuddin 640

20. Landuse Indicator
Identifying Land Use types
Classifying areas
Google Earth Pro ™
(Pro7.1.7.2606)
FAO Data used as a
framework
Big Cities Residential areas
Cropland
Coast line

21. Business Settings
Indicator
Identifying the number of
business setting close to
the coastline from Google
map
Classifying the business
depending on priorities of
the total number settings

22. Transport Asset
Indicator

23. RESULTS & DISCUSSIONS

24. Hazard Map

25. Population Indicator
North upazilas
● High population density (1040 P/km2)
● High iPop→ high iExp
South upazilas
Low population density (230 P/Km2)
Low iPop→ low iExp

26. Land Use Indicator
Main classes :
Crop areas, residential areas, big cities and coastline & forest
South upazilas
• Higher exposure to erosion
• More area is planted with crops
• Big cities located close to coast
North upazilas
• Lower exposure to erosion
• More area is used for residential purposes
• Big cities are located away from coastline

27. Business Indicator
Main classes :
Big markets, small markets and ports
South upazilas
• Businesses are less exposed to erosion
• Decreased markets density decreased population
density
North upazilas
• Busniess highly exposed to erosion
• Increased markets density  decreased
population density
• Increased ports due to increased business
activities resulted in higher exposure rate

28. Transport Indicator
Main classes : Unpaved Roads, Paved Roads
North upazilas
Low percentage of the road asset
Low iTrn → low iExp
South upazilas
High percentage of the road asset
High iTrn → high iExp

29. Exposure Indicator Map

30. Risk Map
North upazilas
- Upper parts
High iPop, iBus→ high iExp
High iexp +Med iHaz→ high CI
- Lower parts
Med iPop, iBus→ Med iExp
High iHaz + Med iexp →Med CI
South upazilas
Low iPop, iBus→Low iExp
Low iHaz +Low iHaz→Low CI

32. ADAPTATION POLICIES FOR RISK REDUCTION

33. RESILIENCE APPROACH
Focused in the Upper Parts of northern upizals where the risk mainly derived from increased
exposure
● Promote green infrastructure solutions :
○ Floating ports-Business settings.
○ Waterways transportation -transportation.
● Identify hotspot areas
● urban planning to address and avoid areas prone to erosion
● Increase public awareness and educate stakeholders.
● Work toward more resilient building materials design codes

34. HAZARD MITIGATION APPROACH
- Relevant to Lower Parts of the northern upizzals where hazard is the main source of risk:
• Heightening and strengthening embankment.
• Putting sandbags and concrete block on the slope of the embankment polder.
• Proper management practices ;improved monitoring to potential breaching parts of the
coast
• Increase number of cyclone shelters.
• Enhance early warning and cyclone tracking system.
• Promote ecosystem services role in reducing hazard ; implement Healthy coastals.

35. CONCLUSION
● A preliminary risk analysis → identify hotspot areas in order to prioritize disaster reduction plans
● 6 upazilas were chosen for the study
● Shoreline retreat (hazard) was computed using geospatial techniques and a buffer zone was
demarcated in order to calculate the corresponding exposure
● Coastal Risk index was computed to analyse the risk of coastal erosion
● The Norther part of the island is susceptible to high erosion rate with a maximum erosion rate of
130 m/year

36. RECOMMENDATION
● Coastal managers should give high priority to the the northern part of the island and deploy the
necessary resources.
● Further, vulnerability need to be assessed and strategic planning should be carried out to increase
resilience reduce impact of climate change (Ashraful Islam, 2015 ).
● Using advanced geospatial techniques Digital Shoreline Analysis System (DSAS) for accurate
shoreline change determination.
● Integrated coastal zone management plays a vital role to mitigate the problem and define suitable
adaptation strategies.

37. REFERENCES
1. Hugh Brammer (2014). Bangladesh’s dynamic coastal regions and sea-level rise
2. Md. Ashraful Islam (2015). Assessment of Coastal Vulnerability Due to Sea Level Change at Bhola Island Bangladesh: Using Geospatial
Techniques
3. Bangladesh Bureau of Statistics. http://www.bbs.gov.bd/
4. Magnus Krantz(B178 1999),COASTAL EROSION ON THE ISLAND OF BHOLA, BANGLADESH,
5. Md. Shamsuddoha,Rezaul Karim Chowdhury;CLIMATE CHANGE IMPACT AND DISASTER VULNERABILITIES IN THE COASTAL AREAS OF
BANGLADESH
6. Rubayat Alam1, Md. Saiful Islam2, Md. Raqubul Hasib3, Md. Zahirul Haque Khan4;Characteristics of Hydrodynamic Processes in the Meghna
Estuary due to Dynamic Whirl Action
7. Mizanur Rahman;Bhola Island, Bangladesh,Risks of erosion and disasters on livelihood
8. The 5th International Coordination Group (ICG) Meeting GEOSS Asian Water Cycle Initiative (AWCI) Tokyo, Japan, 15-18, December 2009:Country
Report: Bangladesh
9. Susmita Dasgupta et al; Vulnerability of Bangladesh to Cyclones in a Changing Climate,Potential Damages and Adaptation Cost

38. In Memory of the 1970 Bhola Cyclone Casualties
Dhirobala Mazumder
(1930 - 1970)
The cyclone has left more than 500,000 people dead including my four
family members and 35 extended family members

39. ধন্যবাদ አመሰግናለሁ ‫شكرا‬ Gracias