Groundwater Abstraction

Question 1

Abstraction

Answer 1

• water is taken from groundwater, mostly used in irrigation snd treatment to produce drinking water
• where water demand is higher than supply water is used up more quickly than it is replenished
• in major aquifers average recharge significantly exceeds average abstraction

Question 2

groundwater discharge

Answer 2

• artificial abstraction
• evaporation
• natural discharge by spring flow and groundwater leakage
• outflow intoadjacent aquifers

Question 3

abstraction process

Answer 3

• accessed via boreholes/wells
• a pump generates a suction in the borehole where water is drawn in
• water table of potentiometric surface depressed to provide gradient to well known as the cone of depression

Question 4

Lowering of potentiometric surface

Answer 4

• excessive amount of abstraction over a prolonged period of time
• chalk aquifer in London, groundwater in steady decline from 1820-1960 after abstraction was in decline
• happens especially in low rainfall areas

Question 5

disruption to streamflow

Answer 5

• reduction
• water is taken up and used artificially less being delivered to the stream
• cause significant drying to soil and plant growth
• Conjunctive Use: abstracted water is used to augment streamflow
• major aquifers can be responsible for widespread streamflow reductions

Question 6

Saline Intrusion

Answer 6

• coastal aquifers
• from adjacent aquifers or direct seepage from ocean
• fresh water is less dense than saline water: floats on the deeper layers
• abstraction lowers pressure head, saline water rises into boreholes

Question 7

Recharge

Answer 7

• only occurs in winter months
• highest demand in summer
• limit summer abstraction form borehole near coast

Question 8

Artificial recharge

Answer 8

• can be used to manage aquifers within the UK
• pump excess water into aquifers during winter months to be covered for summer
• meet demand, lower saline intrusion, reduction in lowered water table
• put back into public supply

Question 9

Rising groundwater levels are also problematic

Answer 9

• rebound near mines
• London underground undermining for foundations are built above water table
• flooding of basements

Question 10

The Environmental agency

Answer 10

• issues licensing for groundwater abstraction based on impacts and conditions
• Kirk & Herbet, 2002
• first step for making water use sustainable is awareness and knowledge of human impacts on the environment

Question 11

Environmental Flow indicator

Answer 11

• Rivers in England
• measures where abstraction may have undesirable impact
• 4 quantitative tests that aim to protect surface water flows, groundwater levels, spring discharged and water quality

Question 12

Abstraction Progress

Answer 12

• since 2008 the environmental agency have changed over 270 licences
• prevents over 30 billion litres of water per year being removed
• aim is to end damaging abstraction of water from rivers and groundwater wherever it is cost beneficial to do so