INVESTIGATIONS ON LAND USE/LAND COVER CHANGE AND CLIMATE VARIABILITY ON RUNOFF GENERATION - A CASE STUDY OF VALAPATTNAM RIVER BASIN, INDIA

摘要

The Land use Land cover (LULC) change and climate variability are the important factors that affect the runoff generation in watershed/river basin. In India, Western Ghats have the characteristics of rich biodiversity and high biological productivity in India. Valapattanam river is one of the important west flowing river in Western Ghats originating in Kerala and flow to the Arabian Sea. In this study, Enhanced Thematic Mapper Plus (ETM~+) images of 2000 and Operational Land Imager (OLI) images of 2014 are used to analyze the LULC for basin and classified as forest, agriculture, wasteland, grassland, plantation and water bodies and urban area. Soil and Water Assessment Tool (SWAT) was used to assess the impact of potential LULC and climate change over the last 14 years (2000-2014) on the discharge with SWAT-CUP for calibration and validation analysis for the Valapattnam River basin. The results revealed that forest area, agriculture land and builtup area were highly dynamic than other classes. During 2000-2014, the catchment area was changed mainly from forest to grassland, grassland to agriculture and agriculture to builtup, and climate change to warmer and drier. The land use change increased the surface runoff but climate change decreased runoff strongly while combined effects of LULC and climate variability decreased runoff. In the catchment area, increased urbanized area and deforestation were the strongest contributors to the increase of runoff at the sub-basinal scale. The results indicated that the SWAT model appears to be useful as a tool to assess the impact of LULC changes and climate variability for the surface hydrologic cycle and to better understand the connection among the surface runoff in the Valapattnam River basin.