bangladesh flooding 2004 Flashcards
human causes of flooding
Deforestation reduces interception - increases surface run-off. Increased soil erosion. More water enters rivers. eg timber
~ population growth in Himalayan headwater countries like Nep puts pressure to produce more food by increasing the area of land farmed so deforestation has increased leading to increased run-off - no leaves to intercept
~ Soil erosion has led to a large amount of silt been washed into rivers and subsequently being deposited on the river bed - reducing channel capacity + increased likelihood of flooding
Bangladesh is an LEDC and it’s lack of money and heavy national debt means little money is available to spend on flood protection methods and defences
increased amounts of urbanisation has led to higher peak flow on the rivers with much shorter lag times and a greater frequency of floods
natural causes of flooding
Bangladesh is a low-lying country with 70% of its land area less than 1 m above sea level and 80% being floodplain made up of fertile alluvial lowland
receives large amount of water passing through from major rivers (the Ganges and Brahmaputra) converging and forming a huge Delta. Both have large volumes of water due to large drainage basins which increase flood risk.
Bangladesh has a tropical monsoon type climate with a hot and rainy summer and a dry winter the hot season prior to the monsoon bake the soil making it’s impermeable and the following annual torrential rains July-September lead to rivers exceeding their capacity and flooding
- about a third of the country floods every year during the monsoon
melting snow from Himalayas increase the flood risks as torrents of melt water enter the river at source - climate change increases this*
eg Gangotri glacier, in the indian Himalayas, feeds the Ganges river. The glacier is retreating an average 25 metres yearly.
- global warming leading to sea level rise - high sea levels cause flow of water coming from the Himalayas to be restricted - Bangladesh will be even more flood-prone in the future because of this
long term effects
people had no electricity for weeks
1 million forced to live in temporary accommodation
crops ruined - food shortages
$7 billion in damages
short term effects
50% off the country was flooded
40% of Dhaka was under water
7 million homes were destroyed
30 million people were homeless
wells polluted - 100,000 suffered water borne diseases
short term management (responses)
emergency supplies for food,water, tents and medicines
boats to rescue people
fodder for livestock
repair and rebuild houses / services
aid from other countries
long term management (responses)
soft and hard engineering
hard:
- build 7 large dams in Bangladesh to store excess water. $30-$40 million and 40 years to complete
- build 350km of embankment
soft:
- reduce deforestation in nepal and himalayas
other examples:
- develop an effective flood warning scheme, flood satellite
- build 5000 flood shelters
opportunities offered by river flood plains and deltas
- natural pond and fields flooded during monsoon season allow people to farm fish and shrimps. income/balanced diet
- sundarbans national park, natural mangrove swamps, gives job opportunities for locals
- Average temperature 20° +, rich alluvial soil and plentiful supply of water allows land to produce three different crops a year eg rice, maize, wheat and sugar cane. therefore a high population density can be supported
- many farmers and living from producing and selling jute as it is the most important natural fibre used in textile industry after cotton
difficulties offered by river floodplains and deltas
- when the Delta is hit by tropical storms fish and shrimp enclosures may be inundated
- tropical storms / river floods can also kill people ~ 2004 july, 800 people
- expensive to transport goods. Roads/ railways have to be built ~ often flooded
- Storm surges and strong winds produced by cyclones have potential to flood large areas, harming water supplies and people can suffer diseases
