Assessment of potential suspended sediment yield in Japan in the 21st century with reference to the general circulation model climate change scenarios

In recent decades, soil erosion by water has become a worldwide problem, especially with climate change and progressive declines in the ratio of natural resources to human populations. Changes in future climate will influence soil erosion, particularly suspended sediment (SS) yield, and alter the effectiveness of water resources management strategies from a water quality perspective. We qualitatively assessed future changes in SS yield in Japan. We focused on the impacts of future hydrological changes projected by two models, the Model for Interdisciplinary Research on Climate (MIROC) and the Meteorological Research Institute Atmospheric General Circulation Model (MRI-GCM), whose results have produced monthly data sets for the whole of Japan. The impacts of future climate changes on SS in Japan depend on the balance between changes in climatic and geologic factors. Methods for assessing impact using the Catchment Simulator were expanded to estimate the SS yield for the whole of Japan. The results indicated that SS generation will increase by the 2090s, with an 8% increase predicted using MRI-GCM data and a 24% increase using MIROC data, compared to present-day values measured by the Automated Meteorological Data Acquisition System (AMEDAS) of the Japan Meteorological Agency. Analysis by month showed the largest increases in SS in September, related to the frequency of extreme events such as typhoons. Increased SS can have negative effects on both society and the environment, including reduced crop productivity, worsened water quality, lower effective reservoir water levels, flooding and habitat destruction. Prediction of the impacts of future climate change on SS generation is crucial for effective environmental planning and management. ⺠We qualitatively assessed the importance of interactions for climate change impacts on SS yield in Japan. ⺠The SS generation increases from 8% to 24% per year for the MRI-GCM and MIROC models. ⺠Monthly analysis showed that a large impact appears during typhoon season in September.