Monitoring Capacity Loss of a Coastal Reservoir Using Satellite Data

Abstract

Periodic surveys of reservoirs are essential to evaluate the decrease in storage capacity due to inflow and trapping of sediment. Conventional hydrographic surveys are time consuming, labor intensive, and expensive. Satellite remote sensing techniques provide time- and cost-effective estimation of the periodical capacity surveys. Water-spread area, estimated from satellite data at different storage levels in a hydrologic year provides an important input for estimation of the revised capacity of a reservoir. In this study, Somasila reservoir located on Pennar river that flows through Nellore district of Andhra Pradesh, South India, has been chosen for evaluating the capacity loss using satellite image data. Digital satellite data pertaining to the years 2012 and 2013 was acquired for different reservoir elevations and the revised water spread areas were extracted. Trapezoidal formula was utilized to estimate the revised capacity of Somasila reservoir. The results show that the loss in capacity is 31.16 M m3 during the period 1987 to 2013. If uniform rate of sedimentation is assumed, in 26 years of operation of the reservoir, then the sedimentation rate would be 1.19 M m3 per year.