Study of morphometrical changes and suspended sediments in Nanak Sagar reservoir of Uttarakhand, India, using remote sensing data & its impact on Ichthyofaunal diversity

Abstract

The present study was undertaken for assessment of morphometric changes and sedimentation rate on thebasis multidated remote sensing data (IRS- I C LISS III) in Nanak Sagar reservoir. The water spread area atFull Reservoir Level (FRL) was 4900 ha from the original survey in year (1962) which was reduced to 2202ha in year 2007 derived through remote sensing data at same elevation. The results obtained indicated areduction of 2698 ha of reservoir area which is about 55 % of the total area. The loss in reservoir capacitywas determined to be 56.19 million m3 (Mm3) (26.78%), which gave an average sedimentation rate of 1.25Mm3 (0.59%) per year due to sediment deposition for the period of 45 year (1962-2007). Total catch declinedyear after year and result on the fish catch presented here are based on ten year fish catch composition datafrom 2000-01 to 2009-10. The total catch during year 2000-01 was 3982.36 quintals (Q) and suddenly declinedto 1350.47 Q in 2009-10. A decline in catch composition of group ‘Ka’ (IMC, Exotic Carp, Mahseer) wasobserved in comparisons to that of other groups ‘Kha-1 (Tengan, Moy, Saul), Kha-2 (Khursa, Patara), Kha-3 (Magur, Singhi, Godi) and Ga (Suiya, Jhinga, Weed Fishes) fishes. The fish catch in group Kha-1 showedan increase from 15.30% to 72.97% in from 2000-01 to 2009-10.