GEOSPATIAL ASSESSMENT OF LAND USE AND CLIMATE CHANGE IMPACTS ON HYDROLOGY OF THE THAMIRABARANI RIVER BASIN, INDIAR. Vidhya and T. Arulkumar
Impacts of land use and climate changes on the stream flow of river basins are a main concern. The study area namely Thamirabarani river basin in Tamilnadu, Southern India experiences an increase in population, wasteland and loss of agricultural land and in terms of climate variables, increasing and decreasing trend in temperature and rainfall respectively. This paper investigates the effect of Land Use and Land Cover (LULC) and the climate change on the water resource components of the basin and the future trends. CLUE-S model is used to simulate land use change, in space and time. Auto-Regressive Integrated Moving Average (ARIMA) time series model is used to analyze temporal pattern of the climate data. Soil and Water Assessment Tool (SWAT) integrated with Geographic Information System (GIS) is applied to predict future impact of the projected land use and climate changes on hydrological component. The results of ARIMA indicate that monthly precipitation predicted value increases in north east monsoon and decreases in southwest monsoon. It also suggests an increase in annual rainfall by 108cm in 2018 and internal variability indicates a changed seasonal peak discharge. Time series analysis of temperature shows an increasing trend in temperature; increase in of monthly average temperature during south-we st monsoon and decrease in monthly average temperature during north east monsoon. Up to 20C increase in temperature is predicted for the year 2018. The CLUE-S model is used to predict the land use as on 2020 with past land use data of 1996, 2006 and 2012 as input and validated with the land use data of year 2006 and 2012. Here, agriculture land use area is predicted to decrease by 4.27%, while waste land, built-up and wetland area were predicted to increase by 1.93%, 1.84% and 0.5% respectively, based on base line data of 1996. Peak discharge has been estimated using GIS enabled SWAT for years 1996, 2006 and 2012. When the land use change has been included in the model, it is found that there is a decrease of 12.4% as against 10.8% with climate parameters alone. The analysis of model results indicates that predicted increase in precipitation will have a greater impact on stream flow than the predicted land use changes, but land use change also plays an important role because it can magnify these impacts. The result shows that the man-made land use change has a greater influence on the stream flow of the river basin.
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