SILT CONTROL OF RESERVOIRS
Entrance of silt into the reservoir may be controlled by adopting following preventive measures.
- Reservoir site should be properly selected.
- If nature of catchment soil contributing water to the reservoir is very soft, the rate of silting will he more, as soft sand will be easily carried by run-off.
- If slope of the catchment is steep, it will also cause more of silting, as steepness would cause increased velocity of flow of run-off and thus more erosion of the catchment soil.
- The tributaries carrying more of silt load to the reservoir should be provided with check bunds
- some where upstream of the tributaries. Check bunds would cause sedimentation of silt load upstream and comparatively clear water will reach the main reservoir.
- The small reservoirs created at the back of the check bunds also supply stored water to the main reservoir when supplies in the tributaries have receded considerably.
- … By increasing the vegetation growth on the catchment, silt entry into the reservoir can be reduced.
- . Silt deposition in the reservoir can be considerably reduced and deposited silt can be scoured by operating sluice gates properly. During floods the inflow of silt is more and scour sluices should be kept open.
- The deposited silt should be dredged from time to time.
- If dam is constructed in stages, the rate of silting in the reservoir is kept low.
- In this measure the dam should be constructed of smaller than the required height and operated for five years.
- After this, dam is further increased in height and again operated for few years.
- By this method capacity / inflow rate is kept small and trap efficiency is kept under check.