Tank study in Belgaum district of Karnataka– A research report by National Institute of Hydrology

The report presents a study of the Rakaskop tank, which caters to the drinking and domestic water purposes of the Belgaum city of Karnataka. In recent past, it has been observed that the amount of water stored during the monsoon season is not sufficient for domestic purposes in the city throughout the year. The study estimates the dependable yield of the tank and also the evaporation from the tank.

The yield of the Rakaskop tank was estimated using the water balance approach. The results obtained were analyzed for dependability. The estimate indicates that the seventy-five per cent dependable yield is 680 mcft. The total utilization works out to 800 mcft leading to a deficit of 120 mcft of water. This deficit can be met by heightening the bund by 8 ft, at which an additional storage of 352.35 mcft of water can be stored. On the other hand, this heightening by 8 ft creates a submergence of about 13 sqmile of agricultural land from the foreground of the tank. Before undertaking the heightening of the bund, a cost-benefit analysis should be carried out to know the benefits that are expected by impounding the water at the cost of the submerging agricultural land.

The estimates of the evaporation indicate that a large amount of water is lost in the form of evaporation especially in the summer period, when there is no inflow into the tank. If the evaporation losses from the tank are minimized, the extra quantity of the water can be made available for domestic and other uses in the summer months.

Also, it is suggested that, an improved pipeline network is needed in the city to minimize the conveyance losses. It is also suggested that, the regression relationship established between rainfall and estimated yield using the logarithmic and power can be made use of for extending the yield results.

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