River Severn Flashcards
Describe the upper course of the River Severn.
The source of the River Severn is on the slopes of Plynlimon.
Annual rainfall exceeds 2500mm and runoff is high.
In the upper course the river mainly erodes vertically cutting down into the landscape forming V shaped valley.
Geology is mainly hard, impermeable.
Describe the middle course of the River Severn.
Average annual rainfall under 700mm.
Rocks are softer and more permeable.
The river channel is wider and deeper
Has more flood plains due to lateral erosion
As more tributaries join the River the discharge increases.
Describe the lower course of the River Severn.
Geology is mainly soft mudstones and lias, sands and gravel.
The river channel widens by the time it reaches Tewkesbury it is 70m wide
The river’s velocity is greatest as there is less friction with the river bed.
Sediment load is high.
More deposition
Explain the River Severn flooding in 2007.
Very high rainfalls in the UK in summer 2007
Rainfall in England and Wales was double the average for June and July.
The period of May to July was the wettest since 1766 leading.
Rain fell on saturated soils leading to runoff to already swollen rivers.
Along the Severn and Avon the large catchments and large volumes of runoff contributed to the flooding.
Tewkesbury located at the confluence of these two rivers was badly hit.
