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