Study on the flood weakness of cities and the flood emergency management system

以大阪府内牙河流域为例，研究了暴雨淹水的发生机制。研究流域分为四个部分：(1)山区；(2)河网；(3)排水管网；(4)流域。(1)径流流量采用运动波模型计算，(2)特征线法用于一维非恒定流分析。在(3)中，基于连续性方程，考虑排水上限进行了分析。(4)采用非结构网格的二维水淹流模型。通过与近期洪水记录的对比，验证了模拟结果的有效性。通过仿真分析，讨论了地下空间淹没的危险区域和防洪设施的作用，并针对地下空间淹没问题，建立了基于蓄水池的数学模型。在该模型中，地下商场和地铁由c-…来处理。多个蓄水池的组合较多，相邻池塘之间的水量交换简单地用溢流公式或流量公式来处理。该模型应用于大阪的内田地下商场及附近的地铁。结果表明，该模型可以适用于实际的复合型地下空间。通过模拟分析，讨论了地面水位和淹没水深对水入侵地下空间的影响，考察了淹没水在地下空间的传播情况。在应急管理和应对城市洪水方面，以福冈和名古屋(东开区)的严重城市洪水为例，总结了这些城市洪水的特点。通过研究指出，日本许多城市在自身恶劣的自然和社会条件下，往往会因江水或海水泛滥或暴雨而遭受洪灾，并且随着城市化的推进，洪灾的脆弱性变得更加突出。同时，讨论和强调了非结构性对策的重要性，如预警系统和信息传递、疏散计划和教育活动。较少

The mechanism of inundation occurrence by heavy rainfall is studied for the Neya river basin in Osaka Prefecture. The studied river basin is divided into four parts ; (1) mountainous area (2) river network (3) sewerage network and (4) drainage basin. In (1), runoff discharge is calculated by the kinematic wave model.In (2), the method of characteristics is applied to one-dimensional unsteady flow analysis. In (3), the analysis based on the continuity equation, considering the upper limit of drainage is conducted. In (4), twodimensional inundation flow model by the unstructured meshes is applied. The validity of simulation results is confirmed by the comparison with the recent inundation records. Through the simulation analysis, the dangerous zone of inundation and the effect of flood control facilities are discussed.With regard to the inundation in underground space, a mathematical model based on storage pond is developed. In this model, underground mall and subway are treated by the c … More ombination of multiple storage ponds, and the water volume exchange between adjacent ponds is simply treated by overflow formula or discharge formula. This model is applied to Umeda underground mall and adjacent subways in Osaka. The results show that this model can be applicable to the real compound underground space. Also, by the simulation analysis, the effect of ground level and inundation water depth on water intrusion into underground space is discussed, and the inundation water spread in underground space is examined.As for the emergency management and countermeasures against urban flood, the heavy urban flood in Fukuoka and that in Nagoya (in Toukai district) are taken and the characteristics of these urban floods are summarized. Through the studies, it is pointed out that many of cities in Japan tend to suffer flood disasters by overflow from the river or the sea or by heavy rainfall under the natural and social severe conditions of their own, and that their flood weakness becomes more conspicuous as urbanization proceeds. While, the significance of non-structural countermeasures is discussed and emphasized such as warning system and information transmission, evacuation plan and educational activity. Less