Thames Basin Flashcards
Where is the River Thames?
England
How long is the River Thames?
346km
What is the course of the river?
- The Thames rises in Cotswold Hills (made out of Jurassic limestone)
- Then it flows Eastwards through a gap between the Chilterns and Berkshire Downs (made out of permeable chalk)
- For the rest it flows over impermeable London clay into the North sea
Where is the driest region in the country?
- The South-East region
- The Thames flows here
What is the effect of the driest region?
- Puts pressure on water resources as the area already struggles to meet the demands
- Growing population doesnt help
What is the average rainfall a year in the driest region?
690mm
Where does London get 40% of its water supply from?
Groundwater in the chalk that lies beneath the city
How does London get water from the groundwater?
- Boreholes are drilled through the clay
- To get groundwater from the chalk aquifer
- Aquifer: underground layer of water bearing rock
What type of river is the Thames?
A lowland river
Why does the Thames not have waterfalls or gorges?
- Its source in Cotswolds is 108 metres above sea level
- It has less force from gravity
- So it lacks in the energy of an upland river that has a source in the mountains
How was the Thames meander formed?
- Thames has a gentle gradient and little downward erosion
- The river does have energy for lateral erosion
- Because it carries large volumes of water
- It flows side to side across its valley
- This forms a meander
What is the effect on the River Thames when sea levels rise?
- The river gained energy
- Because it had to drop further to seal level
- It eroded downwards into its old floodplain
What is the effect on the River Thames when sea levels fall?
- The river lost its energy
- Began depositing more material on its floodplain
Rejuvenation
A river that has eroded down into its old floodplain due to a fall in sea level
What happened each time the river was rejuvenated?
- Formed a new floodplain at a lower level
- Leaving an old floodplain as a river terrace at a higher level
Where are river terraces found?
- Along the Thames valley
- West and East of London
River Terrace
An old floodplain of a rejuvenated river
When was the Thames flood?
February 2014