Examination of Flood Countermeasures Utilizing a Yokohama City Main Rainwater Pipeline and Public–Private Anti-Flood Measures

Abstract

Continuing urbanization has reduced permeable land areas, causing rainwater runoff volumes to rise, which not only increases the drainage burden placed on rivers and sewerage system, but also increases flood damage risk with the increases in torrential rains brought about by climate change. As physical flood control infrastructure has high costs and requires long planning and construction times, more effective utilization of existing infrastructure is required in addition to new construction. Moreover, as urbanization continues, the use of privately owned land for flood control as well as the limited publicly owned land available is increasingly important. This article reports the results and efficacy of a project to create a rainwater management network by connecting multiple pumping stations with the city’s main rainwater pipeline in coordination with river development in a major river drainage basin region, while rebuilding aging pumping stations for continued use, as well as the effectiveness of rainwater storage facilities in underground locations beneath privately owned buildings.