A DISTRIBUTED RIVER RUNOFF MODEL FOR SETO INLAND SEA BASIN AND TREND IN TOTAL NITROGEN LOADING FOR THE DECADE 2006–2015

Abstract

 Accurate prediction of climate change impacts on nutrient loading from watershed is important to discuss adaptive strategies in coastal management. The present study developed a distributed river runoff model for Seto Inland Sea basin to evaluate water and nutrient discharge. Using this model and disclosed observations, we investigated the trends in total nitrogen (TN) concentration and loading in 21 major rivers for the decade 2006–2015. The observed TN concentration had a significant decreasing trend in almost all rivers, which was consistent with the simulation. By contrast, increase trends were found in TN loading and freshwater discharge from all river basins in the simulation. The results suggest that the significant trends in TN concentration and loading are caused by precipitation increase for the period.