Climate Change and the Escalating Cost of Floods: New Insights from Regional Risk Assessment Perspective

Global climate change is expected to alter characteristics of flood events. This study evaluates the rising flood risk and damage potential in the lower Vipava River valley—a transboundary catchment between Slovenia and Italy—under climate scenarios RCP 2.6, 4.5, and 8.5. The area has experienced multiple floods in recent decades, indicating high vulnerability. Using hydraulic modeling for current and future conditions, flood hazard zones were identified and integrated into the KRPAN model to estimate expected annual damage (EAD). The findings show that EAD escalates from €0.97 million under current conditions to €1.97 million under the most extreme scenario. A 20% rise in flood peaks leads to a 1.4-fold increase in damage, while a 40% rise results in losses that are more than double. Buildings show a 2.5-fold increase in EAD, and water infrastructure EAD rises by a factor of 1.9. These results underscore the substantial economic consequences of climate change on flood risk. The study highlights the urgent need to incorporate climate scenarios into flood risk assessments and spatial planning to support adaptive strategies and reduce future damage. These insights are essential for making informed decisions and achieving long-term resilience.