GIS APPLICATION FOR ASSESSING THE EFFECTS OF LAND USE CHANGE ON SURFACE RUNOFF AND SOIL EROSION IN PHATTHALUNG WATERSHED, SOUTHERN THAILAND

摘要

Phtthalung watershed is one of the agriculture dominated watershed of southern Thailand. Paddy cultivation was previously major agricultural activity of Phatthalung watershed but it has been converted to rubber plantation since 1990 due to the increasing rubber price in the local and global market. The study investigated changes of land use resulting in various environmental issues and the surface runoff and soil erosion in Phatthalung watershed of Thailand using Landsat images for two time periods (1976 and 2006) and field measurements. The surface runoff of the same period was simulated by SCS model and the soil erosion was assessed by MUSLE. The results showed that the highest runoff depth was found at the area under paddy field for both observed years. In case of soil erosion, the highest average soil erosion rate was found at the area under rubber plantation, followed by forest and paddy field area.