Study on Reclamation and Flood Hajard Mitrgation in Estuarine Area.

在日本的大多数大城市，河口地区都有大量的大型填海工程。在垦区建设的城市是高度集聚和高度发达的。为从防洪减灾的角度预测围垦引起的流域变化，探讨防洪减灾对策，以期为湾区城市防洪减灾提供理论依据和对策。1.填海对河流泄洪的影响2.填海对洪水、风暴潮和波浪的影响3.洪水和风暴潮的淹没行为，包括对地下空间的入侵.4.填海对海底形态的改变.5.封闭基地水环境的改善。从工程角度探讨了围垦项目的确定方法(规模、形状、施工时机和顺序)。为了减轻洪水和风暴潮淹没造成的预期损失，还讨论和评估了建设性对策和非建设性对策(如预警系统和疏散规划)的效果。

In most of metropolitan cities of Japan, there are a lot of large-scaled reclamation projects in estuarine area. The cities which will be constructed in reclaimed area are conglomerate and highly-developed. Once those cities of high concentration with multi-functions are inundated due to floodings, tangible and intangible damage would be very serious, and an unfathomed socioeconomical impacts result from inundation.This study aimed to predict water basin changes due to reclamation from the viewpoint of flood hazard mitigation, to investigate countermeasures against the flood and/or storm surge inundation, and to contribute to the improvement of flood hazard security in bay area cities. In this study, following subjects were focused.1.Influence of reclamation on river flood efflux2.Changes of flood, storm surge and waves due to reclamation3.Behavior of flood and storm surge inundation including invasion into underground space4.Changes of sea bottom configuration due to reclamation5.Improvement of water environment in a closed basinBased on those results, the influences of reclamation were assessed. The methods to decide the reclamation project (size, shape, timing and order of construction) were descussed from the engineering aspects. To mitigate the expected damage due to flood and storm surge inundation, the effects of constructive countermeasures and non-constructive countermeasures such as warning system and evacuation planning were also discussed and assessed.