Future runoff projections based on land change using integrated Markov-Cellular Automata model and Soil Water Assessment Tool in Lam Pachi Basin, Thailand

Abstract

Surface runoff is a key component of the hydrological cycle. Land use/land cover is a main factor affecting runoff processes. This research quantified the future changes in the runoff yield based on land use/land cover change (LULCC) using as a case study the Lam Pachi (LPC) Basin, a tropical watershed located in western Thailand. Future land change scenarios were projected using the integrated Markov model and cellular automata simulation (CA-Markov), and the impacts of LULCC on runoff yield were evaluated using the Soil and Water Assessment Tool (SWAT). The result revealed that more than half of the Lam Pachi Basin was covered by forest. From the CA-Markov simulation, approximately 7.6% of the LPC Basin would be converted from forest to agriculture in the next 35 yr. The simulation study using SWAT showed a minor increase in the water yield at a basin-wide level, while substantial changes were observed at the sub-watershed level. The increased water yield occurred in the watershed due to land conversion from forest to agriculture, particularly on steeper topography, whereas the same conversion in the flat lowlands resulted in reduced water yield.