River Flooding - Causes

Prolonged rainfall
1. Long period of rain - soil become saturated
2. Further rainfall can't infiltrate - increases run-off into rivers
  1. Increases discharge
Heavy rainfall
1. A lot of runoff - increases discharge quickly
Snowmelt
1. A lot of snow or ice melts into river in short space of time
  1. Increases discharge quickly
Relief
1. If steep sided valley - water will reach river channel much quicker
  1. Increases discharge quickly
Geology
1. If river in area of impermeable rock, more water flowing on surface
2. More runoff - risk of flooding higher
Deforestation
1. Trees take in water (leaves, roots)
2. Cutting down trees increases volume of water that goes to river
  1. Increases discharge
3. Causes soil errosion
4. So soil washed away - raises river bed
  1. Reduces volume of water river can hold
Urbanisation
1. Buildings with impermeable surfaces (roads, concrete)
  1. Increases surface runoff
    1. Increases discharge quickly

Resource summary

	Created by Emily Gibson almost 11 years ago