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

以大阪府内雅河流域为例，研究了强降雨淹没发生的机理。研究的流域分为四个部分；(1)山区；(2)河网；(3)污水管网；(4)流域。式(1)中，径流量采用运动波模型计算。(2)将特征值法应用于一维非定常流场分析。(3)中，考虑排水上限，基于连续性方程进行分析。(4)采用非结构化网格二维淹没流模型。通过与近期洪水记录的对比，验证了模拟结果的有效性。通过模拟分析，讨论了洪涝危险区域及防洪设施的效果。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，地下商场和地铁采用c…More多个蓄水池组合处理，相邻蓄水池之间的水量交换简单采用溢流公式或排放公式处理。该模型应用于大阪梅田地下商城及邻近的地铁。结果表明，该模型可适用于实际复合地下空间。并通过模拟分析，讨论了地表高度和淹没水深度对地下空间积水的影响，考察了淹没水在地下空间的扩散。在城市洪水的应急管理和对策方面，以福冈和名古屋（东海地区）的特大城市洪水为例，总结了这两次城市洪水的特点。通过研究指出，日本的许多城市在自身的自然条件和社会条件恶劣的情况下，容易遭受河流或海洋溢流或强降雨的洪水灾害，随着城市化进程的推进，其洪水脆弱性更加突出。同时，讨论和强调了预警系统和信息传递、疏散计划和教育活动等非结构性对策的重要性。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