Sunday, 30 March 2008

Ganges Delta

Describe the main physical features of a delta and explain how they are formed. You may use labelled diagrams if you wish. (5 marks)

Main physical features of the delta:
Triangular shape
Low lying marshy land
Many distributaries
Banks of sediment

Deforestation which causes soil erosion, and erosion of the highland areas of the Himalayas provides a lot of material which is transported downstream by the River Ganges and its many tributaries. The river slows down as it approaches the sea and, as its current is checked by the sea, it begins to deposit its load of silt. These deposits build up because the sea has a small tidal range and a weak current. This means that the rate at which the river is depositing sediment is greater than the rate at which the tide can remove the material. The river channel becomes choked with the sediment causing the river to split into many channels called distributaries which flow round the banks of sediment. Eventually these banks may become colonised by marsh plants. Gradually the delta is extends out into the coastal waters of the Bay of Bengal.

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