Dams and Reservoirs
Disadvantage of Awsan Dam (8)
- Displacement of population - Seismic Stress - Channel Erosion - Erosion of Nile Delta - Loss of nutrients (no flooding to supply) - Decreased fish catches - spread of diseases due to stagnant water - still doesn't provide expected amount of water
Advantages of Aswan Dam (5)
- flood/drought control - irrigation - hydroelectric power - improved navigation - tourism
Hydrological Changes Upstream because of Dams
- increased evaporation because reservoirs cover larger area - increase in surface stores - reduction in velocity of river - increased sedimentation
Hydrological Changes Downstream because of Dams
- river discharge decreases because water held behind dam = can also decrease velocity - river discharge can be more regular because dam can control it - erosion can lower river bed as there is less sediment to replace after erosion - amount of load transported decreases because less sediment goes across dam = less depositional landforms - salinity of water and ground can increase - water temperature can decrease because water released from reservoirs is colder - water may be less oxygenated than natural flowing water
Reservoir
Artificial store
Dam Case Study
Aswan Dam
Megadam
Higher than 15 m
Upstream of Dam
above the dam and towards the source.
Dam
barrier placed across a river
Downstream of Dam
below the dam and towards the mouth.
Multipurpose scheme
built to serve more than one purpose