Development and Application of Evaluation Model for Interior Flood Damage Mitigation Effect of a Paddy Field Dam

Abstract

Low-lying agricultural reservoirs under the pressure of urbanization in Japan are subject to increasingly higher risk of inundation disaster due to the change in the runoff characteristics by decreasing the area of paddy fields and the recent increase in the frequency and magnitude of heavy rainfall events. The objective of this study is to develop an inundation analysis model for the evaluation of the flood mitigation effect of a Paddy Field Dam project, specifically aiming at low-lying agricultural lands. The model developed in this study is composed of three modules: runoff calculation module in which the runoff from each landuse cell is calculated using water balance analysis, one dimensional unsteady flow module in which flood routing is performed to calculate flow in the channel network, and inundation flow module in which the behavior of flooded water is demonstrated using topographically adjustable cells. One of the unique characteristics of this model is that the runoff from landuse with different attributes are reflected in a realistic but concise manner in the calculation as the origin of runoff. As a result of applying the model to two type of study field, inundation process was verified to be reproduced well.