IB ESS HL 4.2.8 Water Scarcity Mitigation Strategies Questions

Cons: [2] max
a. people relocated from the area to be flooded / loss of communities/villages / loss of livelihoods in the area;
b. loss of habitat to area that was flooded / loss of habitat to construction of the canal/pipeline that carries the water from the reservoir to Beijing / destruction of habitat caused by building of road to the construction site;
c. reduction in flow into the Yangtze river affecting wildlife/fish populations/human settlements / loss of water for the Shanghai area;
d. dam blocks fish migration;
e. dam disrupts/reduces flow of sediments downstream;
f. (weight of water in dam) can trigger seismic movement/earthquakes;
g. increase in insect vectors/water-borne diseases (e.g. bilharzia/malaria);
h. rotting vegetation in dam can release greenhouse gases (methane and carbon dioxide) / it is energy intensive to build and equipment used release greenhouse gases $/ \mathrm{CO}_{2}$;
i. potential loss of water from canals/dams due to evaporation / potential loss of water from canals due to long distance of transfer to Beijing ( 1200 km );
j. it is expensive to construct / pipelines will require continual maintenance which is expensive;
k. over-dependency on a single source could be an issue e.g. drought in the Shanghai region;

Pros [2] max
I. production of hydroelectric power / generates electricity sustainably;
m. provides flood control;
n. provides water supply for Beijing residents / improves availability of safe water / decreases water scarcity;
o. water available for irrigation;
p. water available for industry;
q. avoids use of groundwater/polluted surface water;

Note: Award [2] max if only pros or only cons given
Conclusion [1 max] needs to be balanced considering both sides of the argument for credit and makes a clear value judgement e.g.: While the benefits to Beijing in terms of addressing water scarcity would be enormous, the environmental impacts (e.g. of loss of habitats) and social impacts (e.g. loss of villages and communities) of increasing the dam size would outweigh the benefits.

Conclusion is not mandatory and 3 marks can be achieved through consideration of both cons and pros.