Integrating remote sensing and GIS for groundwater recharge assessment in upper don river basin of Karnataka

The present study was taken up in upper Don river basin of Karnataka, India. The semi arid climate prevails in study area, it is occupied by basalt and other trap intrusions while, vertisols (black soil) is a dominant type of soil. Natural recharge is a vital parameter to be known for ground water budgeting, management and modeling. Ground water recharge was calculated on the monthly time steps using water balance method. All the elements of Thornthwaite-Mather water balance elements were computed using GIS. For micro level planning, the entire watershed (643.5 km²) was sub divided into ten sub watersheds. For analysis, ten years (1998–2007) daily rainfall data was used. Most of the times recharge takes place during September and October months only. Whereas South-West rains during June to August contribute to recharge the soil profile. The annual recharge was in the range of 0 to 20.21% of the annual rainfall, while about 49.50 mm/years i.e., 7.86% of annual rainfall was the average annual recharge of the study area. Further, the yearly average of sub watershed wise annual recharge available was in the range of 46.50 to 503.20 ha m, with an average of 283 ha m. The spatially distributed recharge map for the study area was prepared and annual rainfall-recharge relationships in the form of second order polynomial equations were developed.