Transforming Flood Management in Japan through River Basin Resilience Approach

Challenge

Japan faces more frequent, intense floods as climate change and urbanization expose the limits of dam- and levee-centric river management.

Solution

The RBDRSA initiative applies basin-wide planning, structural and nature-based measures, digital tools, and community action to reduce flood losses and support climate adaptation.

Overview

In recent decades, Japan has experienced more intense and unpredictable rainfall, and recent typhoons have exposed the limits of conventional flood control based mainly on dams and levees. During Typhoon Hagibis in 2019, for example, several rivers overflowed despite extensive flood control infrastructure, causing widespread damage. These events highlighted the need for a broader, more integrated approach to managing flood risk in a changing climate.

In response, the Ministry of Land, Infrastructure, Transport and Tourism (MLIT) introduced the River Basin Disaster Resilience and Sustainability by All (RBDRSA) initiative. RBDRSA is a comprehensive framework that treats each river basin as a connected system, from headwaters and catchments to river channels and floodplains. The approach brings together national and local governments, private companies, and residents to share responsibility for reducing flood risk and supporting recovery.

The Subcommittee on Climate Change Adaptation Measures for River Basins, River Bureau, Council for Social Infrastructure Development (MLIT, 2020), calls for a shift to basin-wide flood risk management. It recommends expanding comprehensive flood control concepts, previously focused on urban basins, to rural river areas as well. The subcommittee also notes that measures to control runoff should involve many actors and address pressures from both urbanization and climate change.

Four components of the RBDRSA approach

The RBDRSA framework is organized around four main components, each addressing a different aspect of flood risk across the river basin.

1. Preventing flooding and reducing floodwater volumes

This component focuses on structural measures and natural retention areas that slow, store, or divert water. Structural measures include levees, reservoirs, and rainwater infiltration and storage facilities. In cities, public parks and schoolyards can function as rainwater retention basins that absorb excess rainfall. Farmland and forests can serve as natural retention areas, storing water in soil and vegetation and reducing runoff.

2. Reducing exposure to flood risks

The second component addresses where and how people live and work in flood-prone areas. Land use planning reassesses development in high-risk zones, encouraging growth in safer locations and limiting new construction in areas with high flood hazard. Flood-resilient building design promotes flood-resistant construction techniques and elevated structures where relocation is difficult. In some high-risk areas, the government supports collective relocation of communities to safer sites.

3. Minimizing impacts and ensuring rapid recovery

This component focuses on preparedness and response tools – including digital information systems – that reduce losses when floods occur. Detailed hazard maps help residents and local governments identify flood-prone areas and plan evacuation routes. Evacuation plans are reviewed and practiced for maintaining readiness. Early warning systems and reliable communication channels support timely evacuation and coordinated responses during flood events.

4. Disaster recovery systems

The fourth component addresses how communities and systems recover after floods. It includes streamlined procedures for restoring essential services, financial support for affected households and businesses, and technical assistance for agriculture, industry, and local governments.

Implementation challenges

The RBDRSA initiative recognizes that no single measure can remove flood risk. Instead, it promotes combining engineering works with natural processes and community-based actions. This requires strong coordination among national and local agencies, upstream and downstream communities, and private actors.

Implementation faces several challenges, and coordination across sectors and administrative boundaries can be complex. Raising awareness about flood risks and promoting community participation require time, resources, and trusted communication. When relocation is considered, authorities must work closely with residents over long periods to build understanding and consent. Sustaining investment in both structural and non-structural measures also demands stable financial and human resources.

Future outlook

RBDRSA represents a shift in Japan’s flood risk management from infrastructure-focused control toward basin-wide, multi-actor resilience as part of climate change adaptation. The initiative’s focus on whole-basin planning, combined structural and nature-based measures, and community engagement reflects current efforts to address more extreme rainfall and river flooding under climate change. As implementation progresses, lessons from RBDRSA can inform continued refinement of policies and practices that support safer, more resilient river basins.

Acknowledgements

This report is based on documents from the Ministry of Land, Infrastructure, Transport and Tourism (MLIT) on the River Basin Disaster Resilience and Sustainability by All (RBDRSA) initiative.

Related information

• MLIT (2020) How to deal with water disasters in light of climate change – A shift to sustainable “watershed flood control” implemented by all stakeholders across the entire watershed (in Japanese) https://www.mlit.go.jp/river/shinngikai_blog/shaseishin/kasenbunkakai/shouiinkai/kikouhendou_suigai/pdf/03_honbun.pdf
• MLIT, Japan, “Promoting River Basin Disaster Resilience and Sustainability by All” (in Japanese)
  https://www.mlit.go.jp/river/kasen/suisin/?utm_source=chatgpt.com
• MLIT, “River Basin Disaster Resilience and Sustainability by All”
  https://www.mlit.go.jp/river/kokusai/pdf/pdf21.pdf