Application of SWAT model to evaluate forest land area change impact on flow regime in upper Ma River basin, Vietnam

Abstract

Assessment of land use change, especially forestland area change effects on hydrological conditions is considered to be indispensable in planning and management of any river basin. The upper part of Ma river basin, Northwest of Vietnam is a typical river basin in Vietnam with variable flow regime and topography, and has been undergoing tremendous land use changes in the last few decades. The present study is an attempt to use SWAT model to evaluate impacts of different forestland area change scenarios on hydrological regime of the upper part of Ma river basin. The SWAT model was calibrated and validated in accordance with the observed daily streamflows at selected gauging stations, using available meteorological and hydrological monitoring data series during 1998 to 2004. Simulated flow regime of the river was analyzed for quantifying implications of different re-forested area (25% and 50% of total 2005-year forested area in the river basin). The result of assessing the forestland area change scenarios effects on flow regime shown that: increasing forest land causes decreasing the mean stream flow in wet season. The preliminary results of this study can be used as decision support information for natural resource planning and management.