NUMERICAL MODELING AND ESTIMATION OF RADIOACTIVE CESIUM MOVEMENT AT THE KUCHIBUTO RIVER BASIN, FUKUSHIMA

Abstract

Radioactive cesium (Cs-134 and Cs-137) dispersed from the Fukushima No.1 Nuclear Power Plant is strongly attached to surface soil layers. To estimate a movement of radioactive cesium with suspended sediment in a catchment scale, a distributed rainfall and sediment runoff model was developed. Radioactive cesium attached to suspended load was modeled by considering a sediment particle size distribution. A constructed simulation model reproduced an observed rainfall runoff as well as an estimation of sediment runoff considering the origin of the source of sediment generation and an estimation of the cesium movement contained in the suspended load.