BY IMPROVING THE GREEN INFRASTRUCTURE FUNCTION OF FORESTS MEASUREMENT OF DISASTER DETERRENCE EFFECT

Abstract

In this study, we measured the disaster deterrence effect by improving the green infrastructure function by forest management in order to control the risk of sediment-related disasters and flood disasters caused by heavy rains that have become severe in recent years. Specifically, we measured the effect of preventing surface erosion and the effect of preventing surface collapse due to forest management in the forest land that is currently abandoned. The former calculated the change in the amount of eroded sediment depending on the presence or absence of forest management by the USLE method, and the latter calculated the change in the slope safety factor obtained from the action of the tree root system to anchor the surface soil to the slope. As a result, it was shown that if forest management such as thinning is carried out appropriately, the frequency of surface collapse will decrease and the amount of eroded sediment will be reduced by an average of 330,000 tons per year. It was also shown that monetary valuation of them using alternative methods would result in a benefit of approximately 7.3 billion yen.