River bank erosion is a major natural hazard in Bangladesh that causes significant land and property loss each year. Three key points: 1) Major rivers like the Jamuna and Padma have widened over 3 km and eroded over 130,000 hectares of land in the last 30 years according to satellite image analysis. 2) Case studies show river bank erosion displacing over 4,000 people and causing over 4 crore BDT in economic losses annually in some districts. A majority of affected people face poverty due to loss of land and livelihood. 3) While structural measures like embankments are used, long-term policies addressing resettlement, land zoning, and afforestation are needed to

1. “River Bank Erosion in Bangladesh.”
Composed by
H.M.A. Mahzuz
Assistant Professor (PhD Fellow),
Department of Civil and Environmental
Engineering,
Shahjalal University of Science & Technology
Sylhet,
Bangladesh.

2. Riverbank erosion is one of the most
unpredictable and critical type of disasters.
It is vastly influenced by rainfall, soil structure,
river morphology, topography of river and
adjacent areas, and floods.
Such calamity took less effect in lives but more in
livelihood as agricultural land and homesteads
along with other livelihood options that are
evacuated.

3. Deltaic sediments of Quaternary formation characterize
most of the lands of Bangladesh. The natural setting of
Bangladesh is between the Himalayas and the Bay of
Bengal together with the prevalence of tropical monsoon
climate.
The catchment area of the major rivers is about 1.65
million square km of which only 7.5 percent lies within
the border of Bangladesh that generates 1200 km3 of run-
off annually, only 10 percent of which is generated within
Bangladesh. In addition to vast quantities of water, these
rivers carry about 1.1 billion tons of sediment every year
and are responsible for the prevalence of flooding and
riverbank erosion in Bangladesh.

4. The combination of the large discharges and
heavy sediment loads with high water content
from the annual wet monsoon, a low degree of
compaction and dredging, and a large amount of
runoff materials result in highly variable and
dynamic channel morphologies to adjust their
bed configurations.
The river channel may shift laterally by more
than 300 meters in any season.

5. Study findings by Center for Environment and Geographic
Information Services (CEGIS) based upon analysis of 30-
year time series of satellite images reveals that the Jamuna
and Padma rivers have widened more than three kilometres
and destroyed about 1,30,000 ha of floodplain land.
One of the most influential phenomenon is that climate
change is expected to disturb the sediment balance. It is
difficult to forecast whether there will be net accretion or
erosion.

6. Riverbank erosion has important implications for channel
adjustment and long-term channel change, meander
development, catchment sediment dynamics, land loss and
downstream sedimentation problems.
Because of poor understanding of riverbank erosion processes,
river dynamics and sediment transport models are weakly
integrated into river management strategies.
Furthermore, such knowledge gap complicated the
relationship between flow energy and bank retreat rates
erosion processes take place in bank erosion system and
because of the duration of process and response along with the
lack of information on erosion or accretion.

7. Despite decades of research, the erosion of cohesive
riverbanks remains difficult to predict.
Models of cohesive river bank erosion must include a
wide variety of erosional processes including fluvial
erosion induced by hydraulic forces and mass wasting
processes related to soil strength and bank geometry.
Bank erosion is strongly influenced by the pore water
pressures and the moisture content within the bank,
which are influenced by hydrologic processes and
riparian vegetation.

9. Figure: A close look of
the eroding Jamuna River

11.  River bank erosion:River bank erosion:
 An endemic and recurrent natural hazard in BangladeshAn endemic and recurrent natural hazard in Bangladesh
 When river enters the mature stage they become sluggishWhen river enters the mature stage they become sluggish
and meander or braid, and continuous water oscillationsand meander or braid, and continuous water oscillations
cause massivecause massive River bank erosionRiver bank erosion..
 It is estimated that about 5% of total flood plain ofIt is estimated that about 5% of total flood plain of
Bangladesh is directly affected and it is seen that bankBangladesh is directly affected and it is seen that bank
erosion is taking place 94 out of 489 upazilla.erosion is taking place 94 out of 489 upazilla.

13.  Some Historical Changes of Physiography & RiverSome Historical Changes of Physiography & River
Morphology in Bangladesh:Morphology in Bangladesh:
 The changes of course of theThe changes of course of the TeestaTeesta from the Ganges to thefrom the Ganges to the
BrahmaputraBrahmaputra during the flood of 1787.during the flood of 1787.
 Recurring floods in Rangpur, Bogra & Pabna districts betweenRecurring floods in Rangpur, Bogra & Pabna districts between
1787 & 1830 accentuated the process of course changes of1787 & 1830 accentuated the process of course changes of
thethe BrahmaputraBrahmaputra from the oldfrom the old BrahmaputraBrahmaputra, which flowed, which flowed
passed Mymensingh town & joined thepassed Mymensingh town & joined the MeghnaMeghna at Bhairabat Bhairab
bazaar, to the Jhenaidah, later developed in to thebazaar, to the Jhenaidah, later developed in to the JamunaJamuna ..
 TheThe Ganges (Padma)Ganges (Padma) flowed separately to the Bay of Bengalflowed separately to the Bay of Bengal
through Tetulia channel during (1764-1772). It has changed tothrough Tetulia channel during (1764-1772). It has changed to
its present course by joining theits present course by joining the MeghnaMeghna near Chandpur.near Chandpur.
 The 1762 earthquake uplifted the Madhupur tract creating theThe 1762 earthquake uplifted the Madhupur tract creating the
Sylhet basin through subsidence compensatory to theSylhet basin through subsidence compensatory to the
elevation of the Madhupur tract.elevation of the Madhupur tract.

14. CAUSE:CAUSE:
-Bends
-Meandering

15. Disaster ManagementDisaster Management
Pre disaster During disater Post disaster
Administrative
-prediction
-govt movement
-awareness campaign
- foreign aid and fund
collection
Technical:
-Marginal embankment
-guide banks
- groynes or spurs
-artificial cut off
- pitching of banks
- pitched island
-miscellaneous methods
Administrative:
-local contribution
-govt guidence
-rehabilitation
Technical:
-temporary protection
-foreign aid
-rehabilitation
-relief fund
-damage assesment

16. Recent Exposure on the Buriganga:
Fig: Bank erosion on the Buriganga

17. Recent Exposure on the Meghna:
Fig: Bank Erosion On The Meghna

18. A Government Project to Protect River Bank Erosion:
The Ministry of Planning & Planning Commission jointly took a project to protect
different eroding places on the both banks of the Surma river flowing through Sylhet at a
length of about 10km by river bank protection of 2352m(new) and repair of existing
revetment works at length of 2395m erected earlier.
The name of the project is Protection of Both the Banks of the River Surma in Sylhet
Town. The project is under the plan of Fifth Five Year Plan.
The project area is located under Sylhet Sadar upazilla in the district of Sylhet.
Some gross information about the project:
Investment cost & annual operating expenditure:
EventEvent
Total (in lakh Tk)Total (in lakh Tk)
Investment cost of the project (including costInvestment cost of the project (including cost
escalation)escalation)
1461.001461.00
Annual operating / recurring expenditure onAnnual operating / recurring expenditure on
completion of the project at normal capacitycompletion of the project at normal capacity
34.3634.36

19. Estimated
quantitative
measurement
of wealth
protection by
the project:
Sl. no.Sl. no. Description of propertyDescription of property No./QuantityNo./Quantity Apporx. value(lakh Tk)Apporx. value(lakh Tk)
11 Mazar of Hazrat Borhanuddin(R:)Mazar of Hazrat Borhanuddin(R:) 11 100.00100.00
22 High School & Primary SchoolHigh School & Primary School 7 (3+4)7 (3+4) 800.00800.00
33 Large scale MadrasaLarge scale Madrasa 55 400.00400.00
44 Bridges on the Surma riverBridges on the Surma river 22 2000.002000.00
55 ShopsShops 780780 2000.002000.00
66 Paved roads on both banksPaved roads on both banks 23km23km 700.00700.00
77 Meghna petroleum depotMeghna petroleum depot 11 700.00700.00
88 Technical collegeTechnical college 11 300.00300.00
99 GraveyardGraveyard 22 200.00200.00
1010 Large rice millLarge rice mill 11 200.00200.00
1111 Police stationPolice station 11 200.00200.00
1212 Circuit houseCircuit house 11 200.00200.00
1313 Leprosy hospitalLeprosy hospital 11 200.00200.00
1414 Forest officeForest office 11 150.00150.00
1515 Water supply machine roomWater supply machine room 11 300.00300.00
1616 Ancient public libraryAncient public library 11 300.00300.00
1717 R&H officeR&H office 11 250.00250.00
1818 BuildingsBuildings 210210 450.00450.00
1919 MarketsMarkets 33 1000.001000.00
2020 Other private buildings & installationOther private buildings & installation L.S.L.S. 750.00750.00
TotalTotal 11200.0011200.00

20. Fig: Photograph of bank erosion on the Surma

21. Fig: Photograph of bank erosion on the Surma

22. Fig: Photograph of bank protection on the Surma

23. Fig: Photograph of bank protection on the Surma

24. Case Study
(Effects of Riverbank Erosion on Livelihood , January 2012
A.F.M Azim Uddin and Jayanta Kumar Basak, Unnayan Onneshan - The
Innovators, 16/2, Indira Road, Farmgate, Dhaka-1215, Bangladesh ):
Two case studies are presented those were conducted in the most
vulnerable regions of Bangladesh
1) Kapasia Union of Gaibandha District, and
2) Kazipur and Khasrajbari Union of Sirajganj District)

26. 1) The study findings revealed that on an average, 256.1 ha and 622.2 ha of
total land area of Gaibandha and Sirajganj respectively were eroded per year
during the period of 1973-2009.
2) During this period, the study areas i.e., Kapasia, Kazipur and Khasrajbari
observed 5.82 ha, 6.89 ha and 9.36 ha erosion per year respectively. In
2011, the erosion was found 60.8 ha, 178.76 ha and 203.36 ha of land
respectively that is an indication of increased erosion rate. The main reason
of such variation is because of climate change induced intensifying rainfall
pattern and unplanned interverntions.
3) From the study, it has been observed that the total economic loss arising
from such erosion were 44,48,736 and 4,19,39,962 BDT in Gaibandha and
Sirajganj respectively.

27. 4) A vast majority of the effected people (45.3 and 40.8 percent in
Gaibandha and Sirajganj respectively) are in the income group of 3001-
4000 BDT (i.e. poor income level ).
5) Empirical data showed that bank erosion displaced a total number of 486
and 4028 inhabitants in Gaibandha and Sirajganj respectively during the
study period.
Table: Eroded area due to bank erosion during 1973-2009 District

28. Figure: Causes of Riverbank Erosion

29. Figure: Comparison of Erosion by Year

30. Figure: Way to Cope Up with Household Loss

31. Table: Migration Pattern observed in Gaibandha
Table: Migration Pattern observed in Sirajganj

32. GOVERNMENT STRATEGIES TO LESSEN THE IMPACT
Government response to this problem at local, regional and national levels
has been limited to structural measures i.e., embankments, barrages, etc.,
and very little attention has been paid in developing non-structural and self-
help strategies.
Most often, measures are taken immediately after the disasters and
interventions are taken in the form of relief provisioning.

33. CONCLUSION:
The marginalized and poor people not only lose property but also
experiences socioeconomic deprivation through displacement. Because of
the dynamic character of the rivers and the failure of structural measures,
the sufferings of the people are assumed to continue. Long-term policies
and strategies should be taken to cope up with the bank erosion taking into
account the social and institutional adjustment measures. Land relocation
assurance is one of the appropriate strategies to cope up with such disaster.
In addition, a floodplain zoning is essential to lessen the vulnerability of
riverbank erosion.

34. Furthermore, measures should be taken in different level to minimize the
loss:
a) Sustainable embankment construction and its maintenance
b) Training on disaster preparedness involving local institution/ local
government
c) Massive afforestation with the experience of local knowledge and its
maintenance
d) Action against deforestation
e) Form an alliance among SAARC countries in order to ensure water
distribution within the subcontinent.

35. THANKS TO ALLTHANKS TO ALL