The maps of land preparation, percolation and seepage losses, evapotranspiration and effective precipitation are integrated using GIS to prepare the maps of irrigation water demand in northwest Bangladesh.
The irrigation water demand of each subdistrict of the integrated layer is calculated using by Eq. 1.
The sub-district level
map of irrigation water demand of northwest Bangladesh is shown in Fig. 9.
The irrigation water demand in the study area varies between 839 and 1,210 mm with an average of 1,057 mm.
The pattern of irrigation water demand is the study area shows that it mainly depends on soil characteristics. Evapotranspiration is the second most responsible factor and then rainfall.