Urban Flood Control Considering River Basin

本文从流域（含城区）的角度研究城市洪水及其治理问题。研究了近年来城市洪水发生的机理，探讨了适宜的由结构性和非结构性措施组成的防洪体系。得到的主要结果如下：1。在日本有道河流域，考虑大坝对水流的控制，建立了分布式降雨径流预报系统。试验模拟结果表明，该系统能定性和定量地再现大坝的预泄、降峰和群控等洪势控制。建立了由山区、河网、污水网和流域4个子模型组成的暴雨淹没流模型，并应用于日本内雅河流域。通过与实际淹没面积或河网水位的比较，验证了该模型的有效性。同时，利用相似的模型，研究了小型蓄雨设施的防洪效果。研究发现，它们可以减少重现期小于50年的降雨的淹没面积。提出了一种既能处理城市地面空间又能处理地下空间的蓄水池模型。模型采用了连续性方程、动量方程和下降公式。将该模型应用于日本福冈市，对1999年福冈洪水进行了模拟。计算结果与实际记录吻合较好。

This study treats an urban flood and its control from the viewpoint of river basin including urban area. The mechanism of recent urban flood is studied and the suitable flood control system constituting structural and non-structural measures is discussed. The main results obtained are as follows.1.A distributed rainfall-runoff prediction system is developed considering flow regime control by dams in the Yodo River basin in Japan. The test simulation results show that the system can reproduce qualitatively and quantitatively flood regime control by dams such as pre-release, peak cut and group operation.2.An inundation flow model by heavy rainfall is developed which consists of four sub-models (mountainous area, river network, sewerage network and drainage basin) and applied to the Neya River basin in Japan. The validity of this model is confirmed by comparing the numerical results with the actual inundation area or the water level of the river network. Also, by using the similar model, the effects of small rain storage facilities for flood control are studied. It is found that they can reduce the inundation area for rainfall whose return period is less than 50 years.3.A storage pond model is developed which can treat inundation of both ground and underground spaces in urban area. The continuity equation momentum equation and drop formula are used in the model. The model is applied to Fukuoka City in Japan, and Fukuoka flood in 1999 is simulated. The computation results show good agreement with the actual record.