WJEC Geology of the Human Environment (GL3) Jan 2003

WJEC – Geology of the Human Environment (GL3) – Jan 2003

2.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 BritainIreland”

Figure 2b

(a) (i) Draw an arrow (labelled F) on Figure 2ato 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 probablelocation of a spring associated with the Chalk.

Explain your answer.[2]

Explanation ……………………………………………………………….…………….

…………………………………………………………………………………………..

(b)(i) Aquifers are permeable. State one otherpropertyof an aquifer that

makes it suitable for groundwater storage. [1]

Property ……………………………………………………………………..….

(ii)Explain how rock texture affects this property.[2]

…...…………………………………………………………………………………..….

…………………………………………………………………………………………..

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.

Question 2

2.(a) (i) Arrow to NW.[1]

(ii)Arrow at Chalk boundary (including outliers)

Explanation - Water table in permeable Chalk

forced to surface by impermeable Gault Clay

(max 2)[2]

(b)(i) High porosity(1) or Good specific yield[1]

(ii)Gaps between grains large/interconnected

Well rounded grains

Well sorted grains

Non cemented pore spaces.

Accept - Interconnected joints, faults, fractures, solution cavities

(max 2)[2]

(c)(i)15m (accept 13 - 17)[1]

(ii)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]

(d)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