CLASSIFICATION AND FUTURE CHANGES OF THE UPSTREAM-DOWNSTREAM BALANCES IN 109 RIVER BASINS, JAPAN

Abstract

 The upstream-downstream balance of population and assets is widely used to understand flood risk in a river basin and minimize it. Although conventional flood control strategies have been developed based on the past balances, now it is required to consider the future balances to handle with flood risk because population declining must cause changes in population distribution patterns. This paper aims to estimate current and future flood risk (flood exposure) and clarify basin characteristics focusing on upstream-downstream balances. The result shows that metropolitan regions have a significant amount of flood exposure in the downstream and balance shifting will hardly occur there. In addition, basins with larger flood exposure in the up-midstream areas show greater balance shift towards downstream.