abstraction Flashcards
(18 cards)
what is water/groundwater abstraction (extraction)
process of taking water from any source either temporarily or permanently
what is most abstracted water used for
irrigation or treatment to produce drinking water
water table
level beneath ground at which the rock becomes saturated
what happens to water in this saturated zone (water table)
water will flow from where it has infiltrated to a point of discharge (a spring, river or sea)
what are aquifers
permeable rocks that contain groundwater
what is groundwater abstraction
-process of taking water from a grounf source
-often pumped through boreholes and wells from underground aquifers as source of freshwater
what happens due to water abstraction
the water table is lowered around the borehole / well
when does the water table fall across a wide area
when rates of abstraction exceed rates of groundwater recharge within an aquifer
effects of over abstraction
-wells dry up
-reduction of water in streams and lakes
-deterioration of water quality
-land subsidence
why is reduction of water in streams and lakes an effect of over abstraction
rivers get a lot of their water via throughflow and groundwater flow from soil and groundwater sources
what causes the amount or proportion of stream water from groundwater inflow to vary
-geogrqphy
-geoloyy
-climate
why does abstraction of water cause a deterioration of water quality
-saline water can migrate inland and upward when freshwater is pumped out of the ground in these locations (saltwater intrusion)
-contaminates water supply
why is land subsidence a result of abstraction of water
-water is part of subsurface support for land above
-when water is taken out of soil and rock, the soil and rock collapses, compacts and drops
how much of Europe’s total freshwater is abstracted anually
approx 10%
how much water does europe abstract a year and what does this mean
-350km^3 a year
-groundwater abstraction is within sustainable levels as much of it will be recharged from infiltrating water
where are issues of water abstraction in Europe greatest
-in countries with lower precipitation totals and high potential EVT
-e.g. Mediterranean coasts of italy, spain, malta and turkey
what is common in Greece
boreholes 400m deep contaminated by sea- water intrusion
example of groundwater abstraction effects in Italy
-overexploitation of the Po river
-region of the Milan aquifer
-Led to a 25m decrease in groundwater levels over last 80 years
