ASSESSMENT OF MIROC3.2 HIRES CLIMATE AND CLUE-S LAND USE CHANGE IMPACTS ON WATERSHED HYDROLOGY USING SWAT

The aim of this study was to evaluate hydrologic impacts of potential climate and land use changes in a mountainous watershed in South Korea. The climatic data predicted by MIROC3.2 HiRes GCM A1B for three time periods (2010-2039, 2040-2069, and 2070-2099) were prepared using a change factor statistical downscaling method. The future land uses were predicted using the Conservation of Land Use and its Effects at Small regional extent (CLUE-s) model by establishing logistic regression model for five land use types with 11 driving forces represented by spatial information. By applying the climate and land use predictions to the Soil and Water Assessment Tool (SWAT), the watershed hydrologic components (including evapotranspiration, surface runoff groundwater recharge, and streamflow) were evaluated. For the predicted 2070-2099 temperature and precipitation changes (+4.8 degrees C and +34.4%), and 6.2% decrease in forest areas and 1.7% increase in urban areas, the combined land use with climate change scenario resulted in more streamflow change (+55.4%) than the single climate and single land use change scenario (+39.8% and +10.8%), respectively. The predicted large increase in future precipitation and the corresponding decrease in forest land are predicted to have substantial impacts on watershed hydrology, especially on surface runoff and streamflow. Therefore, to mitigate negative hydrologic impacts and utilize positive impacts, both land use and climate changes should be considered in water resource planning for the Chungju dam watershed.