Pakistan Flooding 2010

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CASE STUDYPakistan 2010, flooding LEDC

Background 

  • Annual rainfall in central and southern regions - below 250mm
  • The rainfall in the north is only sufficient to feed the headwaters of the nations biggest drainage basin- the Indus
  • Pakistan has a monsoon climate which is divided into dry and warm cool winters and a hot wet  summer monsoon
  • Monsoon usually begin in late June and lats for around three months
  • This rainfall is good as it helps with the growth of many crops such as rice and wheat
  • The rainfall also supports aquaculture and fish farming 
  • As a predominantly rural and therefore agricultural based national economy, these rains are critical to the survival and development progress of its people  

Causes

Physical

  • In the summer monsoon, there was exceptional heavy rainfall, with some of the area reaching twice their average rainfall
  • The nature of the rainfall was short but intense meaning that the Indus river system was overwhelmed so flooding it extensive floodplain.  
  • Some annual flooding was expected but the inundation (flood) was the worst for over 80 years
  • Unusual flows in the upper atmosphere blocked the normal flow of the jet stream that guides the rains, including very heavy rain over the Western Himalayan mountains. 
  • This created a huge deluge of water into the upper tributaries of the Ganges 
  • Many meteorologists have linked the unusual patterns to the 2010 – 2011 La Nina (reversal of normal weather conditions)

Human

  • It is clear that some human activities in Pakistan have contributed to the increased risk of flooding and during the high flow, the River Indus carries a large load of silt especially on the bed
  • This reduces the channels carrying capacity and frequently the river embankments have been raised to ensure that flood water can be contained. In 2010 the exceptionally high river discharge overtopped then 
  • With such a large population of 191 million that is also increasing by 3 million people each year. 
  • Due to the increasing population urbanization has increased deforestation and increased the number of impermeable surfaces, such as tar, surface runoff has

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