This presentation was given as a part of the partial fulfillment of my master's degree.

1. RIVER BANK EROSION IN
BANGLADESH
Md Asif Hasan

2. Introduction
Rivers which cover about 3.4 million hectares of lands are
susceptible to widespread bank erosion. A network of 250
rivers having a total length of 2400km cover the country
flowing down into the Bay of Bengal. In an average year
775000 Mm of water flows through the river systems of the
Ganges, the Brahmaputra and the Meghna and their tributaries
during the monsoon month i.e. from june to October . The
marked seasonality of river flow in this country is responsible
for erosion during the monsoon due to strong current.

3. Causes
 Geological Shape: The flat delta lands of Bangladesh offer little
resistance to the hydraulic forces of its rivers, particularly during
periods of high flow. As a consequence, in many regions rivers
such as the Jamuna run wide rather than deep.
 Mature stage of River: When rivers enter the mature stage (as in
the case with the three mighty rivers, ganges, brahmaputra and
meghna) they become sluggish and meander or braid. These
oscillations cause massive riverbank erosion.
 Sedmientaion in the River beds: 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. In this country about 70% of the total area is formed by
alluvial deposit where silts and silty clays predominate the
top 15m to 25m and clays , sandy silts and sands dominate at
the deeper depths. The soil in the upper layers are mostly
non cohesive and therefore, easily vulnerable to erosion and
scouring .
The alluvial plains consisting largely of unconsolidated
sediments through out the country are not resistant to erosion
by river current and wave action.
Erosion is rapid on the outer circumference of the meanders
Sudden changes of river course known as avulsion are
common during floods and cause rapid bank erosion.
Occurrence

5. Rivers No. of
location
of bank
erosion
Length of
erosion in
km.
a)Brahmaputr
a-Jamuna 38 160
b) Ganges-
Padma 30 94.4
c) Meghan 6
12.8
d) Teesta 8
35.2
e) Minor
Rivers 18 31.2
f) Flashy and
other Rivers 165 77.6
g) Tidal
Rivers 18 83.2
Table: Length of Bank Erosion
in various Rivers of Bangladesh.

6. Table: Month Wise Erosion in Different Upazilas

8. Loss And Damage

9. Factors that Accelerate Erosion
 Stream bed lowering or in fill
 Flooding of bank soils followed by rapid drops in flow
 Saturation of banks from off-stream source
 Redirection and acceleration of flow within the channel
 Poor Soil Drainage
 Wave Action
 Excessive Sand/Gravel Extraction
 Intense Water from Rainfall

10. Impacts of River Bank Erosion
• Social Impact
 Homelessness
 Migration
 Identity Crisis
• Economic Impact
 Loss of Productive
Land
 Loss of Employment
 Risk of Poverty
• Other Impact
 Health Damage
 Criminal Activities
 Building Collapse

11. BANK PROTECTION MEASURES
 Structural measures
 Hard material protection
 Barrier across the river
 Non-structural measures
 Flow area increase
 Flow diversion
 Geo-bag dumping
 Biological protections
 Bank vegetation
 Wooden piling
 Crisscross porcupines