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.
