WIDE-AREA EVALUATION OF FLOOD CONTOROL FUNCTION OF RICE FIELD STORAGE USING 2D FLOOD FLOW MODEL

Abstract

 We quantified the disaster mitigation effect when the agricultural land was converted into a rice field dam over a wide area in the basin on the left bank of the middle course of the Kuma River using a flood analysis model. We also calculated the difference in effect between the case where the rice field dam is placed in the flooded plain and the case where it is placed in the tributary alluvial fan area.

 The peak time of the tributaries became slower due to the wide-area rice field damming, while the water level rose before the peak. Although the rice field dam in the alluvial fan area contributed to the reduction of inundation near the confluence of the main tributary, the conversion of the rice field dam in the inundation plain area increased the inundation depth in the surrounding area and tended to raise the tributary peak slightly. As a result, it was suggested that when positioning the rice field dam in the flood control plan, the difference in function depending on the arrangement should be strategically considered.