50-Assessment of revised capacity of Kharo Reservoir using Remote Sensing & GIS

Abstract

Reservoirs are artificial lakes created by constructing barriers across the river to arrest the flow of excess water. The silt, which gets deposited at different levels of reservoir, reduces its storage capacity. Reduction in the storage capacity beyond a limit prevents the reservoir from fulfillment of the purpose for which it is designed. Conventional methods of reservoir sedimentation survey are tedious, costly and require lot of man power. Data from space platforms can play a significant role in reservoir capacity estimation surveys. Satellite data provide information in the form of contours of revised water spread at different levels. In the present study, the revised capacity and rate of sedimentation in Kharo reservoir of Gujarat has been estimated using remote sensing data and image analysis technique of !MIS 3.0 GIS. The Kharo reservoir is situated on river Kharo in the Palitana block of Bhavnagar district. The total catchment area up to reservoir site, gross storage capacity and live storage capacity are 241.06 sq. km, 15.25 MCM and 14.225 MCM respectively. Seven digital images of IRS 1D/P6 have been used to cover the whole range of live storage. From the analysis of results, it has been observed that the 4.332 MCM of gross storage has been lost in 22 years which is about 28 % of original gross storage. The average rate of siltation in the reservoir has been computed as 8.17 ha-m/100 km2/year. The results obtained from the present remote sensing survey has been compared with the silt survey of 2000 which indicates that the rate of siltation in Kharo reservoir increased from 0.067 M cum/100 sq km/year (1985 to 2000) to 0.115 M cum/100 sq km/year (2000 to 2007). The rate of siltation which has doubled during last seven years emphasized the need for conservation measures and development of catchment area treatment plan.