Land Resource and Hydrological Inventory of Ganganal Sub-watershed for Watershed Planning and Development Koppal Taluk, Koppal District, Karnataka (AESR 3.0) ICAR - National Bureau of Soil Survey and Land Use Planning, Bangalore Watershed Development Department, Govt. of Karnataka, Bangalore ICAR-NBSS&LUP Sujala SWs-LRI Atlas No. 47

Abstract

The average annual rainfall of 631 mm in the Ganganal sub-watershed as recorded from the Irrakalagada station data by KSNDMC. 68 percent, 15 percent and 17 percent of the annual rainfall occurs during kharif, rabi and Summer seasons respectively and exhibited a higher temporal variability. The evapotranspiration estimation tool developed indicates that the watershed water balance is in deficit. The cropping & irrigation choices are not appropriate and need to be altered to shift the deficit water balance. The estimated runoff available to use is 23 mm for an average annual rainfall of 706 mm (2009-2017). The utilizable groundwater is 31 mm (70% of 44 mm recharge estimated). This means the total available water resource combining the soil moisture store for kharif & rabi (124 mm) and utilizable runoff plus recharge is 178 (=124+31+23) The average actual evapotranspiration estimated in the watershed based on the current land use and irrigation practices for the kharif and rabi seasons is 514 mm. Hence the amount of water use for kharif and rabi seasons may be estimated as 642 mm (i.e 125% of AET). This demand for the two seasons is higher by 464 mm, i.e. (642-178). The AET in June-Sept months is 73 % of rainfall. Hence, there is a less opportunity to harvest the excess water through watershed management practices for utilizing during rabi season. The total number of wells present in Ganganal Sub-watershed as per LRI data is 236 (231-Borewells & 5-Openwells). The groundwater level was found from the data obtained from KSNDMC for the nearest station Honnahunsi.