IMPACT EVALUATION OF LAND USE-LAND COVER CHANGE ON THE HYDROLOGY OF SALIPIT RIVER BASIN CAVITE, PHILIPPINES

Salipit River Basin is an important tributary of the Maragondon River Watershed in the Philippines, as it is a major source of domestic and agricultural water supply. With that, it is crucial to develop a prediction model for the management of its water resources. The main objective of this study was to quantify the impact of land use-land cover change (LULC) on the hydrology of the Salipit River Basin using the Soil and Water Assessment Tool (SWAT). Since the basin is ungauged, the calibration and validation were performed using the area-discharge ratio-adjusted streamflow records from the nearby Maragondon River from years 2015 to 2018. The model calibration and validation demonstrated satisfactory Pearson correlation values of 0.81 and 0.77, respectively. The calibrated model was used to simulate five (5) future LULC scenarios: baseline scenario, urban development, reforestation, agricultural expansion, and intensified afforestation. A 23% increase in the urban area resulted in a 9%increase in average annual flow. In contrast, a 53% increase in forest cover resulted in an 11% decrease in average annual flow. Overall, decreased (increased) forest and vegetation cover resulted in increased (decreased) surface runoff and decreased baseflow. Land use and land cover changes, therefore, influence the hydrologic response of the Salipit River Basin.