DEVELOPMENT OF A SIMULATOR FOR FLOOD DAMAGE MITIGATION, AND INVESTIGATION ON FLOOD DAMAGE MITIGATION EFFECTS OF FLUVIAL WOODS ZONE

为了模拟城市地区河水和堤内的复杂淹没过程，并分析防洪措施的经济评价，研制了数值模拟系统。该模拟器包括：(1)模拟流域降雨径流过程的分布式水文模型，(2)基于通量差分割方案和非结构化有限体积法的二维非定常自由面流模型，(3)基于通量差分割方案结合Preissmann槽的污水管网动态网络模型，以及(4)淹没经济调查。以2003年九州暴雨灾害中翁加河流域水鹤市地区的淹没过程为例，对模拟结果进行了模拟，包括假设降雨模式下的淹没过程、防洪措施的效果和经济评价等。此外，还从实验、理论和数值上研究了陆面河流木带对洪水溢流特性的影响。通过实验和数值研究，提出了一个考虑了林区和堤防特性影响的流量公式，并对其进行了验证。

A numerical simulator was developed for simulating complex inundation processes by river water and inside a levee in urban area as well as analyzing economic evaluation of flood control measures. The simulator comprises(1) a distributed hydrological model for simulating rainfall-runoff process in watershed,(2) a 2D unsteady free-surface flow model, based on flux-difference splitting scheme and unstructured finite-volume method, for flood flows in rivers and inundation process,(3) a dynamic network model, based on flux-difference splitting scheme combined with the Preissmann slot, for sewer network, along with(4) inundation economic survey. The simulator was tested against the observed inundation processes in the Iizuka-city area in the Onga river basin in the Kyushu storm disaster in 2003, and then several simulations, which include inundation processes under hypothetical rainfall patterns, effects and economic evaluation of flood control measures and so on, were conducted. In addition, the effects of the fluvial wood zone in landside on overflow characteristics of flood flows were investigated experimentally, theoretically and numerically. A discharge formula, that includes both effects of characteristics of the wood zone and levees, was developed and validated through experimental and numerical investigations.