Impact of Land Use and Land Cover Change on Streamflow of Upper Baitarani River Basin Using SWAT

Abstract

Any changes in the land use and land cover pattern in a watershed can severely impact the hydrological properties of the watershed by changing its streamflow and groundwater characteristics which may lead to further changes in LULC pattern in the area. Hence, it is essential to assess the impact of LULC changes on various hydrological aspects of a watershed. Such an analysis can be carried out by using a simulated hydrological model of the watershed which integrates the GIS data of the area. This study deals with the impact of LULC change on the hydrology of the upper Baitarani river basin. The hydrological model of the study area was simulated in Soil and Water Assessment Tool (SWAT) on a daily time step concurrently from the year 1979 to 2013 using the LULC data of 1995 and 2013 as well as slope and soil data with a warm-up period of five years. The sensitivity analysis is carried out to find the most sensitive parameters which influence the streamflow of the basin. Calibration and validation are done to gauge the performance of the simulated model using global sensitivity approach of Sequential Uncertainty Fitting (SUFI2) algorithm in SWAT Calibration and Uncertainty Procedure (SWAT-CUP) software. Streamflow obtained from the model using 1995 LULC is calibrated from the year 1986 to 1992 and validated from the year 1993 to 1995 using observed streamflow data at Anandapur hydrological gauge station. Similarly, the model simulated using 2013 LULC is calibrated from the year 2004 to 2010 and validated from the year 2011 to 2013. The objective functions in terms of R2, NSE and PBIAS in SWAT-CUP show that the SWAT model has worked satisfactorily. The analysis of LULC change in eighteen years from 1995 to 2013 shows that the area of forest cover, barren land, and agricultural land has decreased by 0.59%, 1.62% and 6.18%, respectively. In contrast, the built-up area has increased by 8.26% during the same duration. The comparison shows that due to land use and land cover change in the Upper Baitarani basin, the mean annual streamflow has increased by 3.78%.