Past, present and future land use changes and their impact on water balance

Landuse change influences the water balance of a region affecting the available water along with the change in the evapotranspiration (ET). The major objectives of this study are to assess the landuse change and its impact on the water balance of the study area, which is a part of the Narmada river basin in Madhya Pradesh, India. Landuse changes of 1990, 2000 and 2011 have been analyzed and the Markov Chain model has been used to predict decadal change of 2020, 2030, 2040 and 2050 landuse. The influence of the past, present and future landuse change on water balance has been analyzed with the SWAT (Soil and Water Analysis Tool) model in the study area. The effect of changes are shown in 12 different sub-watersheds of the area, reflecting an increased water yield (runoff, including ground-water outflow) and surface runoff but decreased ET, which is due to change in the curve number (CN) values (79.85 in 1990 to 84.63 in 2050). Increased CN value in different sub-watersheds of the region has been observed due to a reduction in the vegetation areas, and increase in the agricultural land and settlements. This has caused an increased runoff and decreased ET. The water yield has increased by 6.98% from 1990 to 2011 (1.92 CN increase) and by 17.5% as projected in the 2050 (4.78 CN increase). The actual ET decreases by 3.37% from 1990 to 2011 and by 8.40% in 2050. Simulation with the SWAT using landuse change showed reduction in ET and increased runoff in different sub-watersheds, which needs to be considered in terms of management.