Modelling different flood mitigation measures using SWAT model and comparison of hydrological results with public perceptionGraham, Hannah Claire (Avtor) Bezak, Nejc (Mentor) Šraj, Mojca (Komentor) civil engineeringmaster thesisflood risk management studyfloodsSWAT+ hydrological modelnature-based solutions (NBS)flood mitigation measurespublic perceptionmultidisciplinary approachUnder an increasingly variable future of weather extremes induced by global climate change, increased flooding and associated risks are a stark new reality. The August 2023 floods in Slovenia, with millions of euros worth in damage and 6 deaths, is just one recent example with the news increasingly abundant in such reports from around the world. It is against this backdrop that careful and urgent attention needs to be directed to what mitigation measures could and should be adopted to reduce this risk. The debate between the effectiveness of nature-based solutions (NBS) and other measures is hotly contended. There is much uncertainty in terms of the money, resources and focus that goes into these measures. In order to assess and compare the effectiveness of green, hybrid and grey measures on mitigating the flood risk in terms of reducing the peak discharge and flood peak, and increasing the lag time, a case study of the Gradaščica river catchment was selected. Wetland, retention polder and dam scenarios were developed to illustrate these measures by modelling them using the SWAT+ hydrological model, with a focus on the August 2023 flood event. This analysis showed that wetlands had only a minor effect on reducing the flood risk, whereas retention polders and dams were both able to significantly affect the discharge peak at the Dvor gauging station and the flood volume, as well as to increase the lag time, with dams being particularly effective. Following this hydrological assessment, a public perception analysis was done using data collected from a survey across Slovenia, the Czech Republic and the Netherlands. The survey data was analysed using the Kruskal-Wallis test and a Canonical Correspondence Analysis (CCA) was done to assess the factors that were influencing the public perception results. With a specific focus on Slovenia, and comparing across the general public and three expert groups – water engineers, researchers in the field of flood or water management, and agricultural workers – it was found that there were perception discrepancies between the groups. In general, the public overestimated the performance of green measures, whilst grey measures were considered most effective but least feasible. Comparing the hydrological and public perception results, it was found that most groups rated the grey measures the highest and green measures the lowest in terms of effectiveness, matching the order of hydrological results, although the researchers had a directly opposing view. This study concluded by highlighting the importance of multidisciplinary approaches to flood risk management and how hydrological models could provide more compelling, data-driven illustrations that could aid public in their perception of risks and risk mitigation, to allow for well-informed decisions to be made that are best suited to that particular catchment.[H. C. Graham]20242024-09-06 07:45:52Magistrsko delo/naloga160974sl