Daegwallyeong area in representative slope upland of highland located in Baekdu mountains remains bare for more than six months and is vulnerable to soil erosion after harvest. Therefore, this study was performed to know the characteristic of soil loss by rainfall according to soil series and reduction of soil loss using cover crop and prediction of pollution loading according to change of future rainfall using a specific survey data by rainfall events in small watershed.
Artificial rainfall experiments were conducted to know the soil loss with 16 treatments of 4 slopes × 4 rainfall intensities using 2 different soils, Chahang-series and Saprolite. Saprolite showed low soil loss than 7% of slope, and Chahang-series was increased with increasing slope and rainfall intensity.
In slope upland of highland, soil disturbance by whole plowing is increasing to the possibility of soil loss. For this reason, the soil erosion reduction effect was evaluated by improving soil covering methods in radish planting. 8 different lends of treatments including rye cutting cover, rye planting cover and black plastic mulching in the soil covering methods were examined about characteristics of the runoff and soil loss and radish growing in non-bottom lysimeter with slope 17%. Results of the tests, conventional treatment whereas 2,994 m3 ha-1. For the results of experiment Festuca planting cover and rye cutting cover is might be recommend for soil conservation technology of slope upland.
Results of scenario analysis of changes in rainfall of Daegwallyeong, changes in rainfall 2010s∼2030s, 2040s∼2060s and 2070s∼2090s are increased respectively 6.7%, 9.5% and 19.0% in comparison to rainfall of the average year in highland small watershed. As a Result of the predicted soil loss along BMP scenario, filter strip 4 m is 26∼27%, there is soil loss reduction effect 45∼50% in filter strip 12 m. Changes in soil and water quality due to the farming activities at Chahang small watershed, concentration of CODMn, T-N and T-P in rainy season is higher than non-rainy season, which was higher at the beginning of agriculture in particular.
From the above results, in order to reduce the soil loss and runoff generated in the slope upland, it must be done in a way applicable to small watershed by a combination of these methods that the crop planting methods such as cultivation of cover crops and the physical method such as bypassing, settling pond and the prediction and assessment of changes in future rainfall.