Model Project for Basin-Wide Flood Risk Management

In response to increasingly frequent and severe water and sediment-related disasters caused by torrential rains, linked to recent climate change, a nationwide initiative known as “River Basin Disaster Resilience and Sustainability by All” is being promoted, in which all stakeholders involved collaborate on flood management efforts.
Sendai City is likewise shifting from conventional government-led infrastructure development, to a basin-based flood control approach involving cooperation with citizens. To implement targeted and intensive “River Basin Disaster Resilience and Sustainability by All” initiatives, the City launched the “Sendai River basin Disaster Resilience and Sustainability by All Promotion Model Project” in FY 2024. A total of 20 initiatives are being carried out across various departments, not only in sewage but also in roads, rivers, parks, agriculture, urban planning, education, and disaster risk reduction departments.

Rice Paddy Dams

By utilizing the water retention function of rice paddies, this initiative temporarily stores rainwater in the paddies during heavy rainfall, thereby reducing the volume of water discharged into drainage channels. By allowing the water to flow into the drainage channels gradually over time, flood damage to downstream areas is reduced. Looking ahead, Sendai City is studying implementation methods that will enable effective and efficient countermeasures by referencing case studies from other cities that have already adopted similar efforts.

Stormwater Runoff Reduction for Existing Houses

This is a citizen-participation initiative that reduces the outflow of stormwater from homes into gutters and stormwater pipes by installing a perforated cap on the existing 15 cm diameter pipe that connects each house to the stormwater system. This allows stormwater to be temporarily stored within the residential drainage pipe, thereby easing the load on downstream facilities.