Question : Removal of Silt from Dams- Reservoirs-Lakes

(a) whether the Government has made any survey/study about the silt accumulation in the dams/reservoirs/lakes across the country and if so, the details thereof along with the dams which have reduced the water holding capacity more than 50 per cent;

(b) whether the Government has any proposal to remove silt therefrom and received any proposals from certain States for adopting new technology for the purpose;

(c) if so, the details thereof, Statewise and the action taken on the said proposals;

(d) whether the Government is establishing any new mechanism using modern technology to remove silt from such dams/reservoirs to bring them back to their full water holding capacity and if so, the details thereof including the details of such technology; and

(e) whether the Government has planned any silt-removal programme in the country and if so, the details thereof, State-wise?

THE MINISTER OF STATE FOR WATER RESOURCES, RIVER DEVELOPMENT AND GANGA REJUVENATION & PARLIAMENTARY AFFAIRS

(SHRI ARJUN RAM MEGHWAL)

(a) to (e) A statement is laid on the Table of the House.



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STATEMENT REFERRED IN REPLY TO PARAS (a) TO (e) OF LOK SABHA STARRED QUESTION NO. *155 TO BE ANSWERED ON 20th DECEMBER, 2018 ON “REMOVAL OF SILT FROM DAMS/ RESERVOIRS/LAKES” RAISED BY SHRI BHAGWANTH KHUBA AND SHRIMATI RAKSHATAI KHADSE

(a) Central Water Commission (CWC) has carried out sedimentation assessment studies of 243 reservoirs through Hydro graphic survey which assesses current gross capacity and live storage capacity assessment studies of 124 reservoirs through remote sensing technique.

As per the study, the reservoirs have experienced annual rate of siltation in live storage zone in the range of 0-1% normally. Six reservoirs viz. Sanandro, Gujarat (57.33% in 30 years), Baira, HP (84.27% in 30 years), Mhaswad, Maharashtra (52.04% in 102 years), Kundah, Tamil Nadu (63.07% in 22 years), Nizamsagar, Telangana (60.47% in 62 years), Chandan, Bihar (52.24% in 37 years) have experienced a loss of more than 50% of gross storage capacity.


(b) to (e) While designing a storage project, provision for the Dead Storage is kept to accommodate the silt coming from upstream catchment. The dead storage is so kept as to accommodate the silt for 100 years of project life assuming a certain design rate of siltation which is based on certain factors. Any deposition of silt in the Dead Storage Zone does not affect the performance of the reservoir.

Desiltation of dams to increase its storage capacity is primarily the responsibility of dam owners who are generally State Govts. or Central / State PSUs.

Usually de-silting of large dams is not techno-economically feasible. However, de-siltation work has been taken up at limited scale by some of the dam owners. Under World Bank assisted Dam Rehabilitation & Improvement Project(DRIP), provision has been kept for need-based desiltation of dams.



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