Water Abstaction From The Chalk Of Southern England Flashcards Preview

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Flashcards in Water Abstaction From The Chalk Of Southern England Deck (18)
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1
Q

Where does the water come from that supplies the chalk aquifer?

A

Rainfall that lands on the chalk hills of the North and South Downs and the Chilterns.

2
Q

When does recharge take place?

A

During winter months when potential évapotranspiration is low and soil moisture deficits are negligible.

3
Q

How do groundwater amounts vary?

A

Seasonally

Levels rise from autumn through winter into spring.

4
Q

What happens to évapotranspiration and rainfall during the summer months?

A

Potential évapotranspiration generally exceeds rainfall.

5
Q

What happens to soil deficits and percolation in the summer?

A

Soil moisture deficits build up and little percolation takes place.

6
Q

Where does water abstraction happen?

A

At boreholes.

7
Q

Why is the pattern of water transfer not constant?

A

It varies overtime and location.

8
Q

What can rivers fed by groundwater from chalk aquifers have?

A

Intermittent sections.

9
Q

What are the intermittent streams known as?

A

Bournes

10
Q

What are bournes a natural characteristic of?

A

Chalk downlands

11
Q

What aspect of the springs that feed the rivers changes each year?

A

The positions change

Greater altitude at winter and spring

12
Q

What can happen if there are one or more dry winters?

A

The effective rainfall available for recharge is low and therefore these rivers can dry up altogether.

13
Q

Where have some of the most acute problems with over abstraction been found?

A

In chalk stream systems

14
Q

What percentage of flow for chalk stream systems is derived from underground aquifers?

A

95%

15
Q

What do the catchments of chalk stream systems provide?

A

Underground reservoirs of high quality water that can be abstracted for public supply.

16
Q

What has dramatically reduced the flow in many chalk streams?

A

Abstraction for public water supply and industry

17
Q

When is public water demand the highest?

A

During dry summers

18
Q

What are the human problems associated by overabstraction?

A

Inability to fish
No river views due to encroaching vegetation
No recreational activities