Abstract
Radioactive substances that were widely dispersed by the accident at TEPCO's Fukushima Daiichi Nuclear Power Plant were adsorbed by soil and can be discharged with suspended solids during rainfall. It is therefore important to quantify the movement of the radioactive substances adsorbed by the suspended solids. We have developed a model to simulate the production and transport of suspended solids depending on their particle sizes, because finer soil particles tend to adsorb more radioactive substances than coarser particles. We then integrated the model into a catchment-scale distributed hydrological model to evaluate the spatiotemporal variation in radioactive transport associated with suspended solids in streamflow. With this model, a continuous hourly simulation was carried out in a dam catchment in Fukushima Prefecture. The results show that the model captures the discharge of radioactive substances both in large and small flood events, indicating that the model can be used for event-based prediction as well as for evaluating long-term influences of radioactive substances on water resources.
