The recent increase in climate change impacts has led to consequences such as more frequent and intense rainfall events. Gävle is a municipality that has been particularly affected by this development, with the August 2021 rainfall standing out as a significant event in this context. The August rainfall corresponds to a 300-year rainfall event, with a total precipitation of 167.9 mm recorded between August 17 and 18.

This study aims to identify vulnerable areas to intense cloudbursts within three study areas in Gävle municipality, and to propose measures for how municipal land can be used to reduce the risk of flooding. The method used is a precipitation simulation of the August 2021 rainfall event in Gävle, carried out to complement the municipality’s existing cloudburst data. The precipitation modelling was carried out using the software Hydrologic Engineering Center – River Analysis System (HEC-RAS). To identify vulnerable areas, a multicriteria analysis was conducted, where the identification of vulnerable areas was carried out in relation to the objective of reducing the adverse effects of flooding on human health, the environment, cultural heritage, and economic activity.

Results highlight the most exposed areas according to the defined objectives within the three study sites, showing impacts on infrastructure and critical functions such as a school and a care facility. In addition, the study also identifies existing structures that are considered important to preserve due to their current role in mitigating cloudburst impacts and reducing flood risk. Based on an overview analysis of the characteristics of the high-risk areas, additional cloudburst mitigation measures are proposed, which are then intended to be further developed by the municipality through more detailed site analysis.

Generated cloudburst mapping provides a foundation for identifying critical areas in relation to future climate change with increased precipitation. However, it should be interpreted with caution, as factors such as infiltration should be included to obtain more realistic results in the modelling. Regardless, the results of combining different layers and data to identify risk areas within the municipality are of great significance for their climate adaptation efforts, with the aim of reducing the adverse impacts of flooding on human health, the environment, cultural heritage, and economic activity.