Prediction of 137Cs-Contaminated Soil Losses by Erosion Using USLE in the Abukuma River Basin, Japan

Abstract

The 2011 Great East Japan Earthquake and tsunami triggered a significant nuclear power plant accident. Subsequent measurements of the concentration of cesium-137 (137Cs) showed that the litter and surface layers in the forest areas near the plant were significantly contaminated. This study applied the Universal Soil Loss Equation (USLE), which has been widely used to estimate soil losses from erosion, in the Abukuma River Basin. The greatest soil loss was predicted to be 1762.75 t ∙ yr−1 ∙ ha−1. To predict losses of 137Cs-contaminated soil, a 137Cs-soil transfer factor was applied in place of a crop factor, and it yielded an average contaminated-soil loss rate of 190.65 t ∙ yr−1 ∙ ha−1, whereas the standard USLE calculation yielded an estimated average soil loss rate of 184.14 t ∙ yr−1 ∙ ha−1. Higher soil losses were predicted in steeper areas west of the river. However, contaminated soil may be deposited along a comparatively flat area, such as that on the east side of the river.