Human activity impacts on surface processes - Leaving Cert Geography - Question C - 2014

Dams significantly alter river processes through modifications to the natural flow of water and sediment transport.

Impact on River Processes

1. Flow Regulation: Dams create reservoirs that regulate river flow, which can lead to reduced flooding downstream but may also lower water levels during dry periods. This alteration can impact aquatic habitats that rely on seasonal flooding for ecosystem function.

2. Sediment Trapping: Dams trap sediment that would naturally replenish downstream areas. This can lead to increased erosion downstream and a loss of nutrient-rich sediments that support agriculture and ecosystems.

3. Water Quality Changes: The stagnant water behind dams may experience changes in temperature and oxygen levels, affecting fish populations and other aquatic life.

Examination of Impact on Processes

• Dams often lead to a more controlled and less dynamic river environment, which can have ecological impacts such as altering habitats for fish and other wildlife.
• Further, when sediment is trapped, downstream habitats may suffer from a lack of necessary materials, affecting plants and animals that depend on these resources.

In summary, while dams provide benefits like flood control and water supply, their impact on river processes can have significant ecological and environmental consequences.