Water Abstraction - Factor affecting Water Cycle

Question 1

Define Water Table

Answer 1

. Top surface of the zone of saturation — zone of the soil or rock where all the pores in the soil or rock are completely saturated with water

Question 2

Define Aquifer

Answer 2

. Huge bodies of porous rock or sediment saturated with groundwater

Question 3

Define Groundwater Abstraction

Answer 3

. Process of taking water from a ground source

. It is often pumped through boreholes and wells from underground aquifers, as source of freshwater

Question 4

Define Over Abstraction

Answer 4

If rate of abstraction exceeds recharge within an aquifer

. When demand for water exceeds the amount of water available

Question 5

Name the effects of Over Abstraction of Groundwater

Answer 5

. Level of Water table lowers
. Reduction of Water in Rivers and Lakes
. Salt Water Intrusion
. Land Subsidence

Question 6

When and where might Over Abstraction Occur?

Answer 6

. Area with low rainfall
. Area with high population density
. Area with intensive agricultural activity

Question 7

Explain ‘Salt Water Intrusion’

Answer 7

. When groundwater is over abstracted, the groundwater stores lowers and saline water from the ocean or sea can migrate inland into aquifers

. The groundwater will be contaminated and may be undrinkable

. This occurs in costal regions

Question 8

Explain ‘ Reduction in Water in Rivers and Lakes’

Answer 8

. Rivers get some of their water from ground water flow

. Removing water from groundwater stores through abstraction reduces amount of water for rivers on the surface.

.This can cause rivers to dry up

Question 9

Explain ‘ Water Table Lowers’

Answer 9

. If the level of water table lowers, wells can dry up

. Unless the well is deepened, there will be a water shortage

Question 10

Explain ‘ Land Subsidence’

Answer 10

. Water is sometimes part of the subsurface support of the land above

. When water is removed out of the rock and soil, the rock and soil compacts and collapses

Question 11

Why may water abstraction for a country be low?

Answer 11

. They may have other sources of water e.g. more surface stores of water

Question 12

Can there be salt water intrusion without abstraction of water?

Answer 12

.Yes, there can be salt water intrusion without abstraction of water.

. This is due to rising sea levels along the coast

. Storm surges or high tides in areas of low elevation are also another cause

Question 13

What can cause ground water levels to high and be in high supply?

Answer 13

. If aquifers are located near in permeable rock such as chalk or limestone, there will be be more percolation, hence more groundwater. This also means more supply of water from groundwater stores and less supply from surface stores.

If the aquifers were located near impermeable rock there will be less percolation, into the groundwater stores. It means more water will have to be abstracted from surface stores