Soil loss is one of the most remarkable environmental problems in the world and causes various negative effects to watersheds. Sediment Assessment Tool for Effective Erosion Control (SATEEC) model is a GIS-based model developed to estimate soil loss using the Universal Soil Loss Equation (USLE), however the previous SATEEC model computes annual average annual soil loss over a long period of time.
In this study, the input data (rainfall erosivity index, soil erodibility factor, topographic factor, cover and management factor, and conservation practice factor) of the USLE model were prepared for the four major river basins to reflect domestic conditions. In addition, SATEEC model capable of only average annual soil loss was improved so that the model is able to estimate monthly soil loss. The improved one, ArcSATEEC, provides an opportunity to classify subwatersheds by soil loss, thus was applied in the four major rivers to define the area of concern that soil loss is significant than others. ArcSATEEC was applied to estimate soil loss in the water supply source protection zones of the Geum river watershed and compared with the area of nonpoint source pollution management in Korea.
As a result of comparing the soil erosion by the ArcSATEEC model with the soil erosion by the ''Notification of Survey on the Topography Erosion Status'', the notification led to overestimation of 124.4% in the Han-gang watershed, 153.1% in the Nakdong-gang watershed, 17.3% in the Geum-gang watershed, 17.6% in the Youngsan-gang watershed, and 16.5 % in the Sumjin-gang watershed. As a result of classifying the possibility of soil loss by the subwatershed in the 4 major rivers, the subwatersheds with the highest soil loss was 175.33 Mg/ha/year in the Han-gang watershed, 182.08 Mg/ha/year in the Nakdong-gang watershed, 154.60 Mg/ha/year in the Geum-gang watershed, 154.60 Mg/ha/year in the Yeongsan-gang watershed, and 163.82 Mg/ha/year in the Seomjin-gang watershed. Analysis of the two areas with the greatest potential for soil loss in the reservoir water reservoir in the Geum-gang watershed indicates that the areas include farmlands or have the vulnerable topographic condition to soil loss. As a result of analyzing the possibility of soil loss in the nonpoint pollution source management area in Korea, it was estimated that 60.7% of Geojeecheon watershed exceeded 50Mg/ha/year and that the 70.5% of Jawoon watershed exceeded 50Mg/ha/year.
As a result, it is possible to estimate the soil loss considering the seasonal changes of Korea using ArcSATEEC model, and the model can be used as a means to manage the area of soil erosion or nonpoint source pollution management area. However, since the prediction of soil loss based on the general soil loss formula is to derive a possibility, it should be used as a means of relative comparison evaluation rather than focusing on the magnitude of the predicted value. Long term monitoring studies are required to derive accurate soil loss.