Heavy rainfall

This could affect the shape of the hydrograph because if the rain is coming down heavily non stop the river will rise and cause a flood.

Melting snow

This could have a big impact because the more snow that  comes down the more water there will be on the floor and this could case a flood.

Long periods of rain

If rain keeps coming down for at least 3  days this could cause a flood because 3 days of rain is a lot. Also if the rain keeps coming down into the river Thames it will over flow.

 

Describe how 2 human factors could affect the shape of the hydrograph.

DEFORESTATION

because removing trees reduces the amount of water intercepted and increases run-of.

URBANISATION

towns and cities have more impermeable surfaces.