Greater London - Water Supply Flashcards
How much water does the Thames supply each day?
2.6 billion litres of drinking water to 9 million people every day.
This is increasing due to larger populations and rising wealth demanding more water.
How does the climate impact water supply?
Below average rainfall of 690 mm making it one of the driest places in the UK.
Furthermore, only 250mm can be used by the population as the rest is lost by evapotranspiration.
Luckily frequent winter rainfall recharges aquifers faster than the alternate occasional storms.
How does the geology impacts water supply?
The geology of the Thames basin is a relatively even split between chalk (permeable) and clay (impermeable).
This means that around 1/3 of London’s water supply can be pumped directly from aquifers.
However, nowadays water levels have dropped so significantly that bore holes are now 200m deep to access the groundwater reserves.
Where does London get its water supply from?
Around 80% of London’s water supply is taken from the river Thames upstream.
Groundwater is a very important store of water as it supplies the majority of this river water.
The other smaller source is from the tributaries of the Thames that flow over impermeable clay so overland flow is higher.
The remaining 20% comes from groundwater abstraction outside of Greater London.
