Date | November 2015 | Marks available | 6 | Reference code | 15N.2.sl.2 |
Level | SL only | Paper | 2 | Time zone | |
Command term | Suggest | Question number | 2 | Adapted from | N/A |
Question
(i) Briefly outline how the natural recharge of an aquifer takes place.
(ii) State two methods that can be used to artificially recharge an aquifer.
Suggest how three human modifications of a floodplain can help to reduce flooding.
Evaluate the strategies that have been used to resolve competing demands for water in one named river basin
Markscheme
(i) Natural recharge happens through normal percolation after rainfall/snowfall [1] and/or a gradual seepage from rivers or other water bodies [1].
Credit any valid extension of either point or any comment that relates to the geology/porosity of rock [1] of the area that allows downward movement of water.
(ii) Through creation of recharge basin lakes [1] or water pumped down the bore hole [1]. Credit any other logical reason why more water could be introduced to a region where an aquifer is present, eg drainage diversion [1].
In each case award [1] for explanation of what the modification is and [1] for link clearly established with flooding.
Modifications should be exclusive of each other. Modifications could include:
- afforestation
- changing agricultural practices
- urban changes eg “greening”
- river management schemes ie any measures that decrease the flood (eg flood relief channels, land-use zoning/river restoration schemes, channelization, levees).
For example: Flood relief channels are artificial channels parallel to the river [1] which divert water away from the river in a controlled manner, reducing flood risk [1].
For example: Restoration of rivers allows them to meander and deliberately flood an area [1], reducing the risk of floods downstream [1].
Only modifications on the floodplain may be credited.
Responses will depend on the river basin chosen. The river basin should be named and located.
The competing demands should be outlined and could include farming, industry, domestic supplies, recreation and power supply.
Strategies depend on the river basin selected but could include: customer metering of water, dams and reservoirs, transfer of water, zoning, water use restriction (temporary or permanent), customer advisory services, the use of incentives for installation and/or retrofitting of water efficient equipment, reduction of water use by the water utility, leakage detection and repair programmes and pressure reduction, regulation of the efficiency of water using appliances, especially in new buildings, and use of reclaimed water (eg waste water/grey water) to reduce the need for fresh water supplies.
Good answers may discuss the varying power and/or perspectives of different user groups in relation to how a resolution is arrived at (commercial/human need for water may ultimately take precedence over the needs of ecosystems/wetlands, for instance) Another approach might be to evaluate the importance/success of strategies/actions.
Answers that do not refer to a named river basin and focus on demands only should not move beyond band C.
At band D, expect description of some strategies used to tackle water demand problems in a recognizable river basin.
At Band E, expect either more in-depth explanation of strategies, or some critical evaluation of how successful the strategies have been.
At band F, expect both.
Marks should be allocated according to the markbands.