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Flashcards in Bangladesh Flooding Causes Deck (16):
1

Name of rainy season in Bangladesh

Monsoon

2

When did the monsoon rains begin

June 2004

3

3 main causes

Climatic, Terrestrial processes, Human activity

4

How are monsoon rains caused

In winter ITCZ moves south (leaves high pressure north of India). Dry winds blow out from land to sea.

June, July & August ITCZ moves north- low pressure brings summer monsoon winds which bring moist air off sea

5

What happened late June 2004

Heavy rain swelled Meghna which reached peak early July. Brahmaputra burst early July due to heavy rain in north --> flash floods in N and W central districts --> 38% was covered by water

6

What happened in September 2004

Monsoon hit again- worst in 50 years. 1 week average rain fall was 300mm daily (highest since 1952). This time Ganges caused most of flooding

7

Effect of Himalayan snow melt

Gangori Glacier feeds Ganges- retreats at average of 25 metres a year

8

Effect of cyclones

Bring storm surges and slow down rate at which river water flows into sea

9

What was the type of rainfall that was a key contributor

Relief rainfall from Himalayas

10

How much of country is a delta and floodplain

1/3 on Ganges delta and 80% is floodplain

11

Height above sea level

Most of country is 10 metres below sea level

12

Effect of global warming

Rising sea levels & melting glaciers --> water cannot go away quickly & more water being put into river

13

Effect of storing of water

Stored for irrigation upstream in reservoirs reduced amount of silt deposited so level of land not build up

14

Extraction of groundwater

Lowered water table & caused land to subside by approx 2.5m

15

Urbanisation & population growth

More urbanisation means higher peak flows with shorter lag time and greater peak discharge

Nepal (stage 2) increasing so pressure to provide food and fuel (deforestation) --> SRO, land slides, soil erosion --> river carrying capacity & channel flow decreases

16

GLOF

Glacial Lake Outburst Flood- dam at Tsatitsu Lake burst spilling water into tributaries of Ganges