Study of Flood Damage Reduction by Spillway Installation on a Riverine Levee in a Protected Area

Abstract

　In light of the frequent occurrence of unprecedented heavy rains and floods attributable to climate change effects, the importance of the “River Basin Disaster Resilience and Sustainability by All” initiative is being emphasized and promoted strongly. This paper proposes a flood damage reduction measure by spillway installation on a riverine levee in a protected area. It can prevent levee breaches to reduce flood waters and flood damage. Moreover, this paper presents results of trial application of the method to an area where severe flood disasters have occurred in recent years. Results show that the measure considerably reduces the flooded area, the days required for drainage, and house flood depths. Results also indicate that the average annual damage to paddy fields in the area can be expected to decrease, although the inundation frequency will increase.