SWAT+-based water balance assessment of Ipil watershed in Bohol, Philippines: Spatial and temporal patterns of water availability
Paper Details
SWAT+-based water balance assessment of Ipil watershed in Bohol, Philippines: Spatial and temporal patterns of water availability
Abstract
The Ipil Watershed in Bohol, Philippines, was evaluated for water balance using the Soil and Water Assessment Tool Plus (SWAT+) Model. Geospatial datasets, including a digital elevation model, land use, soil type, and slope data, were used to define the watershed, while climate inputs from Department of Science and Technology-Philippine Atmospheric, Geophysical and Astronomical Services Administration (DOST-PAGASA) covering 2014–2024 were used for simulation. To estimate the main hydrological components, such as precipitation, evapotranspiration, surface runoff, groundwater recharge, and water yield, the model was assessed under uncalibrated, calibrated, and validated conditions. The results demonstrated that by reducing excessive runoff and increasing evapotranspiration, calibration improved model realism and produced more balanced hydrological outputs. Water production and runoff were unevenly distributed among subbasins, with larger values concentrated in the eastern and central areas of the watershed, according to spatial analysis. Strong seasonal variation was revealed by temporal analysis, with an extraordinary annual peak flow of 131.17 m³/s recorded in 2021 and a larger average flow during the rainy season (31.39 m³/s) than the dry season (15.83 m³/s). However, the insignificant baseflow and groundwater outputs indicate constraints in subsurface parameterization. In general, the SWAT+ model performed well in evaluating watershed hydrology and pinpointing regions susceptible to seasonal water scarcity and flooding. The results provide a solid scientific foundation for the Ipil Watershed’s planning for climate adaptation, watershed management, and the sustainable distribution of water resources.
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Anselmo M. Aurestila*, Proceso M. Castil, Manolito C. Macalolot, 2026. SWAT+-based water balance assessment of Ipil watershed in Bohol, Philippines: Spatial and temporal patterns of water availability. J. Biodiv. Environ. Sci., 28(6), 30-41.
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