Causes

• What are physical causes of flooding?

  • Geology
  • Weather
  • Relief
• How does Geology impact flooding?

  • Areas with permeable/porous rock don't flood as easy as water is able to flow through the rocks
  • Areas with impermeable rock is more prone to flooding due to more surface run off - the water will reach the river more quickly
• How does weather increase risk of flooding?

  • Heavy or prolonged rainfall can lead to soil no longer being able to infiltrate - increase in surface run off, so the water will get to the river quicker causing it to flood
• How does relief impact flooding?

  • Flat plains have increased flood risk due to lack of run off
  • Steep gradients such as mountains also have increased flood risk as water will run off into the river quicker
• What are human causes of flooding?

  • Urban - less green space, more homes, more infrastructure
  • Rural - Deforistation, less green space, more farming
• What are urban causes of flooding?

  • Less green space - gardens are being turned into driveways and patios, which means rain/water has no place to soak into
  • New houses - 2011, 72% of available greenfield sites where built on floodplains - less open spaces and more impermeable surfaces lead to rain being washed into gutters which leads to flooding
  • Infrastructure - urbanisation and new buildings lead to everywhere being impermeable which increases flooding
• How does deforestation cause flooding?

  • reduced interception (slows down water movement) of water and trees
  • Trees roots no longer taking water from soil
  • Water moves to rivers quicker and also leads to more loose soil which fills the river beds
• How does farming cause flooding?

  • Pastures are overgrazed and quality of soil decreases - less water can soak into ground
  • Farmers remove hedges between fields, meaning there is more space for small water channels to be created, causing run off