Water Recharge Variability Across Serayu Watershed Using Soil Water Assessment Tool (SWAT)

Abstract

Climate change and land use have an influence on the process of groundwater replenishment. Serayu watershed is categorized as one of the critical watersheds in Indonesia due to groundwater conditions. One that affects groundwater is the ability to replenish groundwater. The purpose of the study was to predict groundwater replenishment in the Serayu watershed. The hydrological model approach (SWAT/Soil Water Assessment Tool) was applied. Spatial data is used in SWAT model analysis, namely: Elevation data, stream, soil types, land use land cover, and climate data. Data analysis using QGIS 3.18 and QSWATPlus tools. The model calibration uses cn2 values while NSE and R2 values are used to evaluate the model. Based on cn2 values, SWAT models show performance that can be used for model implementation. Model validation between before and after the calibration process is (R2) 0.86 while the NSE value is 0.66. When viewed from the water equilibrium ratio, the average water recharge value in the Serayu watershed is 49.5 mm.yr-1 from the total precipitation of 2473.6 mm.yr-1. The largest hydrological component occurs in evapotranspiration and surface runoff (1879.9 and 549.2 mm.yr-1, respectively). The high value of surface runoff indicates that the Serayu watershed needs attention regarding the ability of the land in the water recharge process