The report deals with water conservation measures in the arid and semi arid area of the hard rock region viz Somadevarahalli watershed (Bijapur taluka) and Herehalla watershed (Hangund taluka) of the Bijapur district of Karnataka. Soil and water, the most valuable natural resources for farming, are not preserved in-situ and conserved for future use owing to the inadequacies and ineffectiveness of the existing structures and measures. In view of this, to assess the overall situation of water resources for the development and management of watersheds, the annual and monthly rainfall and its distribution over the study area, and the status of groundwater occurrence has been analyzed.
The water yields of watersheds were estimated using Soil Conservation Services (SCS) method with different initial abstraction conditions and peak discharges for peak annual rainfall series. The probable maximum one-day precipitation and corresponding runoff was also estimated for the design of conservation structures. A survey was carried out in order to find the effectiveness, merits and demerits of the soil and water conservation structures. Recommendations for the improvement of the existing structures were also made.
The boulder bunds, field boundary bunds, nala bunds and check dams constructed by the farmers get very limited success in controlling the problems of runoff and soil erosion as well as in providing irrigation to the crops through surface or groundwater sources. More percolation tanks at the appropriate locations and land leveling, especially in the middle and lower reaches, would help not only in containing the problems of runoff and soil erosion but also in providing irrigation to the crops. Farmers are most likely to accept improved soil water conservation techniques that address their priorities.
As a result, the soil conservation technique that is best for the farmer may not be those that conserve the soil well. The recommended Soil and Water Conservation (SWC) structures are positioned on the contour while farmers choice of technologies are boundary based leading to problems in implementation.
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