EVALUATION OF IMPACT OF VEGETATION ON FLOOD WARER LEVELS IN THE UMEDA RIVER AND STUDY OF APPROPRIATE CUTTING PLANS

Abstract

 The Umeda River is a small to medium-sized river located in Toyohashi City, Aichi Prefecture, which is prone to rising water levels during floods due to vegetation growth. This study utilized a combination of field survey and numerical modeling to assess the impact of in-channel vegetation on flood levels. Sensitivity experiments were conducted on vegetation height, considering vegetation conditions, and vegetation management plans were proposed. The sensitivity experiments revealed that it is crucial to maintain vegetation height below 2 meters to mitigate flood risks effectively. Furthermore, the study identified that vegetation on the right bank significantly contributes to the rise in water levels during flood events. Notably, the Umeda River experiences the highest frequency of floods in September. Consequently, clearing vegetation on both sides of the river by the end of August is considered to reduce the risk of flooding.