Water Abstraction In The London Basin FINISH Flashcards
What do the chalk layers form beneath the London area with the uplands of the Chilterns and North Downs?
A syncline
Is chalk porous?
Yes
How is water in London normally extracted?
Though boreholes and Wells
What became exploited and when?
During the 19th and the first part of the 20th century, the chalk-basal sands aquifer had been increasingly exploited.
Why was the chalk-basal sands aquifer becoming increasingly exploited?
Due to increased industrialisation and the associated development of groundwater sources.
When was the peak of abstraction?
1960s
How far did the groundwater levels in central London drop in the 1960s?
Groundwater levels beneath central London had dropped to 88m below sea level
What did the 1960s drop in water lead to?
A large depression in the water table and a small cone of depression to the east below the River Roding in Essex
What has happened since the mid-1960s?
Industries such as brewing in central London relocated or were closed down
What replaced the industries that closed down?
Economic activity turned to service industries and commerce rather than heavy industry.
Why did groundwater levels start to recover?
There was no more heavy industry to abstract the water
By how much each year were groundwater levels increasing by the early 1990s?
By the early 1990s, groundwater levels were recovering by as much as 3m/year
What is a threat concerning rising groundwater levels?
The London Underground and building foundations could be affected by flooding.
What does GARDIT stand for?
General Aquifer Research, Development and Investigation Team
What has led to the implementation of GARDIT?
The threat of rising groundwater levels
