Land Use Planning on Debris-Flow Fans

Land use planning is the most influential option for managing levels of natural hazard risk, as high-risk land uses can be avoided before an event occurs; and existing uses can be regulated to reduce risks. With international responsibilities for countries to address risk reduction for disasters—including land use planning—the Sendai Framework for Disaster Reduction and the United Nations Sustainable Development Goals provide two sources of mandates for countries to reduce risks through land use planning. Three key roles can be identified for planners in creating and maintaining resilient and sustainable communities: 1. ‘Mainstreaming’ resilience into planning—integrating resilience into land use and development considerations via the planning and implementation process; 2. Enhancing risk management processes—ensuring land use planning issues and opportunities are built into natural hazard management processes; and 3. Building back better—driving pre- and post-event recovery planning as it relates to land use and the built environment. To enable planning for debris flows, mapping the debris-flow extent is key, so that appropriate risk-based zoning and policies can be developed and implemented. Three case studies are presented to highlight the role of planning in managing the risk from debris flows, from increasing restrictions to the managed retreat of a high-risk area. The case studies present proactive and reactive planning responses to the debris-flow hazard and risk, examples of how the debris-flow extents can be mapped, and associated land use restrictions applied to reduce risk. While our perspective is predominantly from Aotearoa New Zealand, there are many themes and challenges raised that will be common across many countries. These include how to manage existing development on debris-flow fans.