First, precipitation is infiltrated into subsurface or is discharged through surface. Infiltration water is discharged into groundwater or is evaporated. This is called precipitation partitioning. This phenomenon can be quantified by the Horton index. This study analyzed effect of climate and watershed characteristics on precipitation partitioning using the Horton index. In the Nakdong river basin, the Horton index is primarily affected by precipitation of climate factors. Considering precipitation and landscape characteristics of watershed, predictability of the Horton index is improved. Especially, average slope of watershed is significant indicator among landscape characteristics.Key words

For the assessment of climate change impacts for the Byeongseong stream, CSIRO-Mk3.0 is selected as future climate information. The projections come from CSIRO Mark 3.0 used to simulate the green house gases emission scenario known as A2. Air temperature and precipitation information from the global climate model simulations are converted to regional scale data using the statistical downscaling method known as multi-site precipitation generator. Downscaled climate data from global climate model are then used as the input data for the soil and water assessment tool to generate regional runoff and water quality estimates in the Byeongseong stream. As a result of simple sensitivity analysis, the increase of CO 2 concentration leads to increase water yield through reduction of evapotranspiration and increase of soil water. Hydrologic responses to climate change are in phase with precipitation change. Climate change is expected to increase water yields in wet season. In dry season, stream flow is expected to be reduced slightly. Soil losses and nutrient discharges are also in phase with precipitation change. However, it should be noted that there are many uncertainties in such multiple-step analysis used to convert climate information from global climate model based future climate projections into hydrologic information.

For the assessment of climate change impacts for the Byeongseong stream, CGCM 3.1 T63 is selected as future climate information. The projections come from CGCM used to simulate the GHG emission scenario known as A2. Air temperature and precipitation information from the GCM simulations are converted to regional scale data using the statistical downscaling method known as MSPG. Downscaled climate data from GCM are then used as the input data for the SWAT model to generate regional runoff and water quality estimates in the Byeongseong stream. As a result of simple sensitivity analysis, the increase of CO2 concentration leads to increase water yield through reduction of evapotranspiration and increase of soil water. Hydrologic responses to climate change are in phase with precipitation change. Climate change is expected to reduce water yields in the period of 2021-2030. In the period of 2051-2060, stream flow is expected to be reduced in spring season and increased in summer season. While soil losses are also in phase with water yields, nutrient discharges (i.e., total nitrogen) are not always in phase with precipitation change. However, it should be noted that there are a lot of uncertainties in such multiple-step analysis used to convert climate information from GCM-based future climate projections into hydrologic information.

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