2.
WJEC – Geology of the Human Environment (GL3) – Jan 2003
Figure 2 is a geological map and cross section of the geology around
Cambridge. The water supply for the region is mainly obtained from
wells located within the Chalk aquifer.
Adapted from N.H. Woodcock
“Geology and Environment in Britain & Ireland”
Figure 2b
(a)
(i)
Draw an arrow (labelled F) on Figure 2a to show the probable
direction of groundwater flow through the Chalk along the line
X - Y.
[1]
(ii)
Draw an arrow (labelled S) on Figure 2b to show the probable
location of a spring associated with the Chalk.
Explain your answer.
[2]
Explanation ……………………………………………………………….…………….
…………………………………………………………………………………………..
(b)
(i)
Aquifers are permeable. State one other property of an aquifer that
makes it suitable for groundwater storage.
[1]
Property ……………………………………………………………………..….
(ii)
Explain how rock texture affects this property.
[2]
…...…………………………………………………………………………………..….
…………………………………………………………………………………………..
…………………………………………………………………………………………..
(c)
Figure 2c shows a section through a supply well in the Chalk during
pumping.
Figure 2c
(i)
Estimate the original depth to the water table in the well prior
to pumping.
[1]
…………………………………………….. metres
(ii)
Describe and explain the local effect of pumping on the
water table in Figure 2c.
[2]
…………………………………………………………………………………………..
………………………………………………………………………………………….
……………………………………………………………………………………….…
(d)
Using your knowledge, state one potential source of
groundwater pollution of aquifers and explain how this might be
identified and controlled .
[3]
Source ………………………………………………………...……………………………
Explanation…………………………………………………………………………………
………………………………………………………………………………………………
………………………………………………………………………………………………
………………………………………………………………………………………………
Total 13 marks
Notes for answers
These represent suggested answers and do not necessarily represent all the possible
acceptable alternatives of a mark scheme.
2.
(a)
(i)
(ii)
Question 2
Arrow to NW.
Arrow at Chalk boundary (including outliers)
Explanation - Water table in permeable Chalk
forced to surface by impermeable Gault Clay
(max 2)
(b)
(c)
(d)
[1]
[2]
(i)
(ii)
High porosity(1) or Good specific yield
Gaps between grains large/interconnected
Well rounded grains
Well sorted grains
Non cemented pore spaces.
Accept - Interconnected joints, faults, fractures, solution cavities
(max 2)
[1]
(i)
(ii)
[1]
15m (accept 13 - 17)
Describe (max1 mark)Cone of exhaustion/depletion/depression
Dimensions (1)Max 10m deep
Max width - ~7m
Explain(max1 mark) - Pumping is greater than recharge
[2]
[2]
Holistic depending upon choice.
Possible pollution sources: E.G.
Septic tank waste, Leachate from landfill
Farm pollutants (Nitrates/pesticides), Industrial chemicals
Mining waste/drainage
Identification:
Chemical testing of water samples from springs/boreholes
Identify the extent of pollution plumes.
Control: E.G.
Saltwater incursion - reduce and/or rearrange borehole pattern of
abstraction (summer v winter pattern)
Farm pollutants better land management (e.g.
reduce use of artificial fertilisers/
reduce ploughing in autumn etc.
Landfill - use of containment - synthetic/clay liners/leachate
collection and drainage system.
[3]
Total 12 marks
ESTA would like to thank the WJEC for allowing this question to be published on GEOTREX. Any
comments should be directed to the Subject Officer for Geology at the WJEC.
15/04/2007