Causes of floods
Relief
Rock
Rainfall
Soil
Impermeable rocks
Land use
Clay soils
Water takes longer to pass through due to its small pores.
The impermeable rocks don't let the water pass through them so the water flows directly to the river making it overflow.
Land is steep so the water flows fastly into the river causing it to overflow
Towns and Cities
Water cannot soak into the concrete and tarmac, so the water stays where it landed.
Natural
Natural
Natural
Human
Heavy Rain
Large amounts of rain can make the river overflow.
Natural
Snowfall
Long period of rainfall
The soil underground gets filled with water (until there is no more space for more), so the water has to flow through the surface directly into the river.
Natural
Natural
When temperature rises the snow melts and large amounts of water are released into the rivers.