Integrated evaluation of flood mitigation measures: A multidisciplinary approach combining hydrology, economics, and public perception

Increased flooding is becoming more prevalent under an increasingly variable future of weather extremes, highlighting the need for effective mitigation strategies. Different flood mitigation measures are available, ranging from classical structural (grey) solutions to nature-based solutions (NbS). This study assessed and compared the hydrological effectiveness, cost-effectiveness, and public perception of green (NbS), grey, and hybrid flood mitigation measures in the Gradaščica River catchment, Slovenia. For the hydrological assessment, a SWAT+ model simulated wetland, retention polder, and dam scenarios. Results showed that wetlands had a minimal effect on flood hazard, reducing flood peaks by up to 3%, while retention polders and dams reduced flood peaks by 51% and 73% and flood volumes by 28% and 58%, respectively. The economic analysis found wetlands to be less cost-effective than retention polders and dams. However, it should be noted that wetlands provide additional diverse co-benefits. The public perception analysis revealed significant discrepancies in perceived effectiveness, feasibility, and acceptability of flood mitigation measures across target groups, including the general public, water engineers, researchers, and agricultural advisors. While most groups ranked dams as most effective and wetlands as least effective, aligning with hydrological findings, researchers held a directly opposing view, and the public generally overestimated the performance of green measures. By examining hydrological effectiveness, cost-effectiveness, and public perception across flood mitigation measures, the research highlights the need to integrate multidisciplinary approaches to develop robust flood management strategies – an essential lens as communities confront escalating climate-driven flood risks. • Hydrological, economic and social perspective of three measures was evaluated • Dams and retention polders were more cost-effective than wetlands • Wetlands reduced flood volume and peak discharge only marginally • Stakeholders' perceptions often do not match the hydrological effectiveness • Integration of diverse perspectives in developing flood risk management strategies is needed