EVALUATING THE RISK OF EROSION FROM RAPID FLOWING RIVERS USING A LARGE ENSEMBLE DATA-SET

Abstract

 This study aimed to analyze external forces and to estimate high erodible sites under the current and future climate scenarios using d4PDF downscaling data. The Toyohira River is a rapidly flowing river that flows through the urban Sapporo area; therefore, high-speed currents develop, leading to conditions that have traditionally made the area vulnerable to flooding, from which erosion is likely to occur. To estimate high erodible sites, we first calculated the outflow of 3000 and 5400 cases of d4PDF data based on current and future climate forecasts, respectively . Next, the current and future climate scenarios were classified according to the rainfall distribution using cluster analysis, and external forces were analyzed. In addition, the high erodible sites were evaluated from the calculation of the hydraulics on the Toyohira River channel using the results of outflow calculations in the present climate scenario as an external force. Thus, it is estimated that greater flooding than has ever been previously experienced will occur owing to climate uncertainty, even in the present day. It is further estimated that some areas are highly erodible, and care should be taken when planning river management strategies.