Reservoir Sedimentation Analysis through Field studies and Hydrographic Survey

The objective of the research is to analyse the field data obtained from hydrographic survey and estimate the rate of sedimentation and storage capacity of the reservoirs. In this study, two major reservoirs, namely Srisailam reservoir and Sriramsagar reservoir, in South India are considered. On the Srisailam reservoir, the soundings were recorded at an interval of 5m and on the Sriramsaga reservoir, the soundings were recorded at an interval of 2m along the predetermined ranges. Average speed of the boat for accurate data collection is usually 3.5 to 4.5 knots. The collection of data during the survey and data editing is done using Navisoft Survey software. The hydrographic surveys were conducted to the extent of maximum water level (MWL), the balance from MWL to FRL ( full reservoir level) is supplemented by remote sensing techniques. The capacity of the reservoir are estimated using Prismoidal formula. From the field data, it can be stated that there is loss in the storage capacity with this sedimentation process and is about 2612Mm³ and 850Mm³ respectively for Srisailam and Sriramsagar reservoirs. It is estimated that rate of sedimentation is about 12.367ha.m/100km²/year at Srisailam and 30.1ha.m/100km²/year at Sriramsagar reservoir. It is observed that rate of sedimentation in the Sriramsagar reservoir is very high and hence authorities have to take precautionary measures.