PROCOAST - a probability based tool for coastal flooding

Rising sea levels pose an increasing risk to Sweden’s coastal municipalities. Storms and extreme weather have already caused significant damage to buildings and infrastructure, and as sea levels continue to rise, coastal flooding is expected to become both more frequent and more severe. At the same time, there is substantial uncertainty about how much and how quickly sea levels may change. This makes it difficult for municipalities, businesses, and public authorities to make well‑founded decisions about long‑term planning and investments.

Today, simplified and static methods are often used to plan for future sea levels, which seldom provide sufficient understanding of the actual flood risk. The project addresses this challenge by further developing SMHI’s Sea Level Simulator 1.0 (SLS) model (Hieronymus, 2023) and creating a national tool for probabilistic sea‑level projections. The model is based on a probabilistic approach that accounts for the large uncertainties in future sea‑level rise and calculates risks for specific locations and time periods.

The project has three overarching objectives: to develop an open and accessible tool for probabilistic sea‑level projections; to support users in integrating the tool into planning and risk management; and to contribute to a new standard for coastal planning in Sweden based on probabilities rather than static water‑level estimates.

The model will be made available as open‑source software and complemented with a dynamic database that can easily be updated with new research findings and measurement data. The project is carried out in close dialogue with users and includes a case study in Trelleborg Municipality.

The project strengthens Sweden’s capacity for climate adaptation and contributes to more sustainable and resilient coastal communities. It also has the potential for international outreach as a part of the research network BLUECO‑TAP through the Sustainable Blue Economy Partnership.