16-Jan-2023: Water Crisis Due to Dam Sedimentation
United Nations Institute for Water, Environment and Health report on dam sedimentation
- In 2050, 50,000 large dams across the world will lose 24-28% water storage capacity due to sediment trapped in them
- Water reservoirs have already lost about 13-19% capacity to sedimentation
- United Kingdom, Panama, Ireland, Japan, and Seychelles will experience the highest water storage losses by 2050 from 35-50% of their original capacities
What is Sedimentation with Respect to Dams?
Sedimentation is the accumulation of sediments such as sand, gravel, and silt at the bottom of a reservoir created by a dam. This reduces the overall storage capacity of the reservoir and may require dredging to remove the sediment.
What is Dredging?
- Dredging is the process of removing sediment that has accumulated at the bottom of a reservoir
- Mechanical dredging with a dredge machine or hydraulic dredging with a high-pressure water jet can be used
- The sediment removed during dredging is typically disposed of in a designated area away from the dam
Causes of Sedimentation
- Erosion upstream of the dam
- Runoff from urban and agricultural areas
- Natural processes
- Climate change
- Deforestation
- Poor dam maintenance
Consequences of Dam Sedimentation
Environmental:
- Reduced water storage capacity in the reservoir
- Increased risk of dam failure
- Loss of habitat for aquatic species
Economic:
- Increased cost of maintenance and dredging
- Loss of hydroelectric power generation
- Reduced irrigation and water supply for agriculture and industry
- Loss of revenue from recreational activities
- Damage to dam structure and turbines
Solutions:
- Regular inspections and monitoring
- Emergency action plans
- Environmental impact assessment
- Public consultation and participation in the decision-making process