Abstract:
Land-use change is a dynamic and multidimensional process that links nature with human activities. It directly influences soil, water and atmosphere and hence is directly related to many global environmental issues. Understanding the hydrologic response of watersheds to physical (land use) and climatic (rainfall and air temperature) change is a critical element of water resource planning and management. Land-use changes can significantly affect surface water runoff, flood frequency, baseflow and annual mean river discharge. Hence, the specific objective of this study was to understand the land-use change that has occurred over the years in five river watershed areas in Goa, India, from the hydrological modeling perspective. The watershed areas of five rivers across the state of Goa were selected for this study. These rivers are the Kalna, Sal, Talpona, Galjibag, and Khandepar. Satellite images for five years from 1977 to 2018 were used. The remote sensing data (from LISS III, Landsat 1-5, and Landsat 8) were geo-referenced and merged. The image classification for change analysis and the various spatial analyses were performed using software, such as ArcGIS 10.3, TerrSet 18.31 and Microsoft Office 2010. The most recent data (2009 to 2018) show that there has been a decrease in the forest cover in all the five watershed areas, except in the Galjibag watershed. This decrease was greatest for the Sal watershed (5.75 percent). The Kalna and Galjibag watersheds showed the greatest increase in the built-up area. The results indicate that the Sal watershed is witnessing rapid urbanization and the Khandepar watershed is experiencing the least. These results can provide useful insights for generating future land-use scenarios to carry out hydrological modeling exercises in these five watersheds and to facilitate prediction of water flows.
