Assessment of sedimentation in Nanak Sagar reservoir of Uttarakhand, India using remote sensing technique

Abstract

In present scenario excessive siltation leading to drastic deduction in water storage capacity is a stumbling block for reservoirs. Reduction in water spread area at a specified elevation over a period is indication of sediment deposition in the reservoir. Reduction in the storage capacity of a reservoir hinders the purpose for which it was proposed. Thus assessment of sedimentation becomes very indispensible aspect for the management and proper operation of the reservoirs. For this purpose, an observation was proceeded to fathom the sedimentation of Nanak Sagar reservoir, located on the Deoha River in the Tarai region of Uttarakhand using multi-dated Remote Sensing (RS) images. IRS LISS III remote sensing data for the year 2007 and original capacity curve were optimized in the study of the capacity loss to various water levels. The morphology of the reservoir has been changed significantly due to sedimentation during the period 1962 to 2007. The reservoir has lost a total of 56.19 Million Cubic Meter (Mm3) by dint of sedimentation which is accounted as 26.78% of the total capacity during last 45 years and average deposition was computed as 1.25 Mm3 (0.59%) per year. It's concluded that the maximum siltation deposited on upper region of the reservoir on the basis of huge difference between original cumulative water volumes and derived cumulative water volume at corresponding elevation of the reservoir.