Improving flood maps through community engagement
Developing locally relevant flood hazard and risk maps requires more than advanced modelling. By engaging directly with communities on remote atolls in the Republic of the Marshall Islands, Deltares is learning from local knowledge to improve flood projections and support climate-resilient planning.
Low-lying atoll islands in the Republic of the Marshall Islands (RMI) are highly vulnerable to coastal flooding driven by waves, high water levels, tropical cyclones, and rainfall. These hazards are expected to intensify under climate change and sea level rise. At the same time, data availability and logistical constraints in remote atoll environments pose challenges for robust risk assessments.
As part of a new project under preparation, the Strengthening Coastal Protection and Food Security for Rural Climate Resilience Project, supported by an Asian Development Bank (ADB) ADF-14 grant, Deltares is developing high-resolution flood hazard and risk maps for the atolls of Arno, Jaluit, and Mili under present-day and future sea level rise scenarios.
The study is financed by the Water Resilience Trust Fund under the Water Financing Partnership Facility (Financing partner: Government of the Netherlands).
Deltares’ work integrates environmental data, exposure and vulnerability information, and advanced numerical modelling with our models Delft3D, XBeach, SFINCS and Delft-FIAT, to quantify flood hazards and their impacts on communities, infrastructure, and livelihoods. For this, we develop the first atoll-scale flood hazard and risk maps for Arno, Mili, and Jaluit atolls as a core planning tool.
Alessio Giardino, Principal Climate Change Specialist, and Mark Bezuijen, Principal Environment Specialist, Co-Team Leaders of the Strengthening Coastal Protection and Food Security for Rural Climate Resilience Project, Asian Development Bank:
“Building climate resilience starts with understanding risk. By combining advanced flood modelling with the knowledge and experience of local communities, this project is developing the first high-resolution flood hazard and risk maps for rural atolls in the Republic of the Marshall Islands. These maps will provide a strong evidence base for better planning, targeted investments, and long-term climate resilience.”
Engaging with local communities
“It is one thing to conceptually know how atolls are formed, modelling how the waves break on the reefs and knowing these sandy islands are just 2 meters above sea level – but it is eye-opening to see it in person”, says Tim.
“Beyond all the detailed flood mapping and software development work I do day-to-day from Delft, in the end it is all about people and their resilience in living at the coast.”
To develop locally relevant results, Deltares works with an experienced community consultation and data collection team through its subconsultant Tonkin+Taylor and partners. During a field visit to the atoll of Mili, the team engaged with local communities to learn about their experiences with flooding from the ocean, lagoon and rainfall. Community members shared their knowledge by mapping flood experiences and identifying valued assets and impacts on their livelihoods.
These insights provide valuable context for interpreting model results and improving the accuracy and relevance of the flood hazard maps. The team also received direct feedback on the first SFINCS flood maps, strengthening the connection between local knowledge and technical modelling.
Tim: “In order to develop locally relevant flood hazard and risk maps for remote atolls in the Marshall Islands, I had the opportunity to travel far away from home and visit two remote atolls in the RMI. By joining our community consultation team, I could learn first-hand about people’s flooding experiences and use this to improve our ongoing modelling efforts”.
Results
The survey results will support the design and prioritization of interventions under the ADB-financed project, including coastal protection and community-based adaptation measures. The Deltares team also joined site visits to Arno Atoll by an ICEM-led consortium that is leading design of the other project components forcoastal protection and food security. This helped ensure integrated work between the team teams supporting the project design.
With the field visits completed, Deltares is now advancing the modelling of multiple flood hazards across all inhabited islands of the three atolls and translating these results into risk assessments. The outcomes will contribute to spatial planning and adaptation guidance, supporting evidence-based decision-making and strengthening long-term climate resilience in the Republic of the Marshall Islands.
