Assessment of the water cycle impact by the Budyko curve on watershed hydrology using SWAT and CO2 concentrations derived from Terra MODIS GPP

Greenhouse gas and aerosol emissions from human activities continue to alter the climate and are likely to have significant impacts on watershed hydrological cycles and stream water quality. We applied the Soil and Water Assessment Tool (SWAT) to evaluate how CO2 impacts the hydrology of a watershed. The goal of this study is to evaluate how potential CO2 changes would impact the hydrologic components in the forest-dominant Seolma-cheon watershed (8.48 km2) in South Korea. Using an image from the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard Terra, the CO2 flux was estimated as the sum of the Gross Primary Productivity (GPP) and Ecosystem Respiration (Rec) following the method of Lloyd and Taylor (1994). To assess the water cycle impact, the SWAT results for certain hydrological components, such as total runoff (TQ), surface runoff (SQ), lateral runoff (LQ), soil water content (SW) and evapotranspiration (ET), were analysed to generate Budyko curves. In the field of watershed management, SWAT modelling using CO2 concentrations as an additional parameter provides a better understanding of the role of ET and soil moisture in ongoing and future climate changes.