LAND USE LAND COVER CHANGE IMPACT ON THE HYDROLOGY OF WAINGANGA BASIN UNDER CHANGING CLIMATE

Abstract

The present study analysed the impact of Land Use Land Cover (LULC) changes on the streamfiows in Wainganga basin at Ashti station under changing climate. Changes in rainfall and temperature trends were analysed using Mann-Kendall test and Sen's Slope Estimator test. Detection of change point in trends of rainfall and temperature were carried out using Pcttitt-Mann-Whitney test. Overall, it was found that annual rainfall has decreased by 8.45% in the basin during 1901-2012. and 2.93 % during 1972-2007. The most probable change point in annual rainfall was found at 1948. Analysis of temperature trends shows an increase in temperature by 2.530C during 1901-2012. and by 0.81°C during 1972-2007. The probable change point in annual temperature was detected at 1975. LULC data were derived from remote sensing data for the years 1972, 1989 and 2008. Analysis of LULC classes have shown that there are two prominent classes in the basin namely Crop Land and Forest cover. Overall, Crop Land has increased by 3.51% during 1972-2008 whereas Forest cover has decreased 4.67 % during the same period. Variable Infiltration Capacity model was used for simulating streamflows in the basin at Ashti station. Nash-Sutcliffc efficiency. Coefficient of Determination and Relative error during calibration period (1972-1991) was found 0.8422, 0.9197 and -4.05 % respectively. and 0.72. 0.85, and 0.01% during the validation period (1992-2007). Simulation with different land use land cover during 1972-2008 depicts reduction in mean annual streamfiows by 0.42%. The model was run with 2008 LULC data during 1972-2008 to assess the impact of climate change only. Analysis demonstrate a non-significant decreasing trend in the basin showing 3.98 % decrease in mean annual flows. VIC model was also run to study the combined effect of LULC and climate change for the entire period (i.e from 1972 to 2007) using three LULC data 1972, 1989 and 2008 representing durations 1972-1980, 1981-1998 and I 999-2007, respectively. Annual streamfiows demonstrate a non-significant decreasing trend in the basin with a 4.34% decrease in mean annual flows.