Author(s): Yasunori Muto

Linked Author(s): Yasunori Muto

Keywords: Retarding Capacity; Paddy Fields; Inundation Simulation; Climate Change; Land Use Change;

Abstract: Inundation processes and retarding capacity of wetland paddy fields were evaluated using a commercial inundation simulation software, AFREL, based on a 2-D shallow flow model. In addition to the present precipitation, predicted precipitations for the end of this century based on RCP8.5 were given to the model, and how the flood control function is affected was examined. Moreover, how land use change in the test field including housing land development and highway embankment construction will change the flooding characteristics there is also of interest. A scenario of the housing land development was considered based on a prediction by an urban development model and the highway planning. The simulation results successfully illustrated temporal variations of the inundated area and its depth distributions for both the present and future scenarios. The annual maximum 24-hours precipitation in the future adopted in this study was only about 10% larger than in the present condition, therefore inundation process does not change so much by only adopted the precipitation change. However, when adopted the tidal level change together, inundation depth and volume become quite larger. The water level in the rivers and channels there strongly affected by the tidal level, so that change more markedly influences inundation than the precipitation change in the tested range. Land use change by raising its elevation for housing reduces the total inundation volume, whereas, in contrast, inundation depth in the paddy fields clearly gets worse, 10 to 20cm deeper than before. Although the developed lands themselves is secured from inundation by land elevation rise, flood risk and the cost of its alleviation can become higher in total.

DOI: https://doi.org/10.3850/38WC092019-1265

Year: 2019