Generation of monthly irrigation maps for India using spatial interpolation techniques

Abstract

Considering the current water resources problems and rapid increase in its demand, the importance of effective utilization of water resources cannot be underestimated if India has to remain self reliant in food production. Point ETc (crop evapotranspiration) can be calculated by multiplying point ETo (reference evapotranspiration with appropriate kc (crop coefficient) values on a monthly temporal scale. Subtracting the monthly point effective rainfall values from corresponding monthly cumulative point ETc, the point net monthly irrigation requirements can be estimated. Spatially interpolating the point net monthly irrigation requirements by kriging, monthly net irrigation requirement (NIR) maps can be generated. Such maps, although readily available for most of the developed countries, have not yet been developed for developing countries like India. This kind of readily available standard net irrigation requirement maps can be very useful in obtaining reliable irrigation demands in new areas. Therefore, in this paper, an attempt has been made to develop monthly net irrigation requirement maps for India. To grasp the spatial distribution characteristics of the net irrigation requirement for the dominant crop of the season and agroecological region (AER), geostatistical analysis was performed on the normal monthly NIR derived from 32 years (1971-2002) data of 133 IMD (India Meteorological Department) stations uniformly distributed over the country. It was observed that ordinary kriging produced best results and hence was used to produce the final net monthly irrigation requirement surfaces for all the months.