The reasons why river levels discharge fluctuate (relief (Gentle slopes or…
The reasons why river levels discharge fluctuate
Amounts and type of rainfall
However, when temperture warms and that snow melts many days' worth precipitation can end up in rivers and cause flooding.
Snowfall in another factor to take into account, rivers fall in the UK as precipitation is often sotred as snow during cold snaps.
The most obvious rasons for river flooding. Long steady prolonged rainfalll will produce rivers which rise slowly but can flood.
Gentle slopes or flat land allow water to penetrate into the soil and increase lag times.
In addition, steep slopesalso can cuases more through flow within the soil.
Steep slopes tend to reduce the amount of infiltration of water into the ground, this water can then flow quickly down to rivers as overload flow.
The relief of the land can also have an impact.
GEOLOGY Rock Type
Impermeable rocks such as shales and clays encourage water to flow overland and into river channels. This speeds up water flow and makes flooding more likely.
Permeable rocks encourage a slow transfer by groundwater flow
This is increased if the land is ploughed up and down steep slopes, as water can flow quickly along the furrows.
This can lead to more surface runoff.
In arable farming, soil is left unused and exposed to the elements for periods of time.
When trees are removed much more water is suddenly availble and transmitted rapidly
Trees also use up water as they grow.
Much of the water that falls on trees is evaportated or stored temporarily on leaves and branches.
Water is transferred quickly to drain and sewers and then into urban river channels.
Building on a floodplain creates impermeable surfaces such as tarmac roads, concrete driveways and slate roof.