Towards implementation of hybrid solutions for flood risk management under climate change

Climate change is expected to affect the frequency, magnitude, and seasonality of several rainfall-related hazards, including flooding as one of the costliest hazards in Europe. Recent studies have shown that flood risk in Europe is both increasing and decreasing, with increases in most eastern and southern European countries, including Slovenia and Czechia. In addition, significant changes in the seasonal occurrence of floods have also been observed in Europe, thus challenging conventional approaches to flood risk management.As natural hazards have major impacts on infrastructure, human lives, and habitats, and cause large social and economic damages, it is clear that adaptation measures aimed at both prevention and mitigation of impacts must be considered to cope with climate change. To deal with the changing occurrence and characteristics of floods, different types of measures need to be adopted, including green, blue, and grey measures or combinations of these. Although their application is currently emphasized, purely green or blue-green measures in some cases may not be insufficient to cope with predicted future climate hazards. Additionally, implementation of such measures often encounter resistance in planning departments and among decision makers due to institutional path dependency related to the history of utilizing grey infrastructure measures. This is especially the case for some Central-Eastern European countries. An alternative are hybrid solutions that combine parts of grey and green infrastructure, since these kinds of measures can reflect the variety of environmental conditions. However, not much attention has been given to the documentation and evaluation of hybrid infrastructure in comparison to purely green measures. Hence, there are still several open questions related to the implementation and functioning of solutions combining elements of green and grey measures, so called hybrid solutions.The main objective of this contribution is to present the theoretical framework, research design and initial research steps of a newly launched international project focusing on: (i) enhancement of documentation and standardization related to hybrid solutions, (ii) development and testing of applicability and social acceptability of specific hybrid infrastructure in different environments and climate change scenarios, and (iii) environmental modelling and evaluation of effectiveness of different measures from the perspective of the flood risk management. Within the project, the effects of hybrid solutions on flood hazard and hydrological regime of the landscape will be modelled for selected small catchments in Slovenia and Czechia, but the standardization of hybrid solutions will enable to extrapolate our results beyond Central and Eastern Europe. Acknowledgment: The research was conducted within the project [Evaluation of hazard-mitigating hybrid infrastructure under climate change scenarios] co-granted by Slovenian Research Agency (J6-4628) and Czech Science Foundation (22-04520L).