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Flood risk assessments

A flood risk assessment is a process used to understand how likely flooding is in a specific area and what the possible consequences might be. It helps identify both where floods may occur and how severe their impacts could be. To do this, four main factors are examined. The first is flood hazards, meaning the probability and size of potential floods. The second is exposure, which refers to the buildings, infrastructure, and assets that could be affected. The third is vulnerability, or how sensitive these assets are to flood damage. The final factor is performance, which looks at how well existing flood protection systems, such as levees, drainage networks, or natural barriers, can reduce risk.

Flood risk assessments use information such as rainfall patterns, land elevation, drainage capacity, and proximity to rivers or the sea. They are usually carried out when planning new developments or infrastructure projects, or when reviewing and updating flood management plans. Geographic Information Systems (GIS) and computer modelling are often used to map areas at greatest risk. Assessments can also test how effective different adaptation strategies are, such as mangrove restoration, wetland protection, or the construction of flood walls.

In the Caribbean, several issues deserve particular attention. One is compound flooding, which happens when different events—like heavy rainfall and storm surges—occur at the same time, making flooding worse. Another is cascading impacts, where flooding causes a chain of problems, such as damaged roads, contaminated water supplies, or disruptions to ports and trade. Vulnerability assessments are also important for identifying critical infrastructure and at-risk communities that need extra protection. As part of climate adaptation, flood risk assessments give communities and governments the information they need to plan safely. They support decisions on where to build, how to design stronger structures, and where to invest in drainage systems or protective barriers. 

Feasibility & Local Applicability

In Aruba, Curaçao, and St. Martin, conducting flood risk assessments can be challenging. Limiting factors include limited access to detailed topographic and hydrological data, outdated drainage infrastructure, and rapid urban development in vulnerable areas. In St. Martin, steep terrain and informal hillside settlements increase flash flood risks, while Curaçao struggles with coastal modeling uncertainties and urban expansion. Aruba, though less flood-prone, lacks consistent rainfall projections and community-level preparedness. Across all three islands, integrating social vulnerability and climate projections into assessments remains a key hurdle for effective climate adaptation planning. Flood risk assessments require specific and recent data as well as technical capacities. Generally, the support of knowledge institutes and funding organizations is needed to carry out detailed, large scale assessments. 

Co-benefits

Flood risk assessments offer several important co-benefits. By identifying areas at high risk of flooding, they help prevent economic losses by guiding safer land use and infrastructure planning. This means fewer damages to homes, businesses, and public services during extreme weather events. Assessments also support the design of effective evacuation routes and emergency plans, making it easier and safer for communities to respond during floods. 

Equity & Vulnerability Considerations

When conducting flood risk assessments, it's important to consider equity and vulnerability to ensure that all communities are protected. This means identifying groups who are more exposed to flood risks—such as low-income households, informal settlements, elderly populations, or people with limited mobility—and ensuring their needs are reflected in the assessment. These communities often live in high-risk areas with poor infrastructure and limited access to emergency services. Including these communities in the assessment process will add valuable insights. 

Costs

Medium – High | Costs of flood risk assessments will vary depending on the scale, location and complexity of the project. Especially the need for site specific, high quality data, modelling skills and stakeholder engagement can drive up costs. 

Case-studies & Examples

Literature

Adaptation Options Overview