Rivers of Bangladesh

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Rivers of Bangladesh

Meghna, Ganges, Brahmaputra

The Drainage Basin

Extensive, covering much of Bangladesh, parts of India, Nepal and

China. The Himalayas and Tibetan Plateau form the rivers' watershed.

The river Brahmaputra detours over a thousand kilometres as the river

has not been able to cut a valley through the resistant rock of the

Himalayas. The flood plain covers about 50% of Bangladesh's land area.

The river erodes material in its upper course in China, India and

Nepal, carrying huge amounts of sediment to be deposited as the river

slows crossing the floodplain and delta of Bangladesh. The river

enters the Bay of Bengal through its distributaries in the delta.

How and why does the river flood ?

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1. MONSOON & SNOWMELT : along the delta, huge tidal waves can be

whipped up in the storm conditions of the Monsoon season (May to

October). These waves can reach 7 metres in height and therefore have

very destructive effects. Islands in the delta such as Sandwip island

house the very poorest of people in Bangladesh. They are forced to

live on the stretches of land with greatest flood risk. They argue

that no one in government is interested in protecting their land.

2. DEFORESTATION: some scientists argue that large scale clearance of

forests in the Himalayas for firewood, furniture and sporting

equipment for other countries is one cause. Forest clearance exposes

the soil to rainsplash which loosens soil particles and surface run

off.

3. OVERFLOW: The increase in soil erosion adds to the silt / sediment

load of the river. The rivers in Bangladesh carry 1600 tonnes of silt

per kilometre. River's channel fills with debris & there is less room

for water which overflows.

4. CHANNEL STRAIGHTENING / CANALISATION: increasing control of the

river through concreted sections & straightening can actually increase

the river's speed (smooth sides reduce friction). This means more

water is carried faster downstream. This can be controversial -

building up concrete or stone levees can prevent floodwater draining
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