Flood modelling and hazard assessment for extreme events in Riverine Basin

Throughout the history of mankind, floods have caused destruction and negatively impacted communities. Recently, effects of climate change and the increasing rate of anthropic activities in flood-prone areas are aggravating the dangers posed by floods to people. Hence, it is crucial to have a better understanding of flood hazard aspects, particularly when considering pedestrians. Indeed, one of the main reasons for fatality during flood events is walking through floodwaters. Although authorities strongly advise against wading in floodwaters, people continue this dangerous behaviour. Alternatively, evacuations or the accessing of flooded areas by emergency services might be necessary. The scope of this research work is to contribute to improving flood hazard assessment and to the design of flood evacuation plans from a pedestrian perspective. To enhance flood hazard assessment a mechanics-based method has been improved by considering effects of terrain slope and updating values of human body characteristics, as well considering body mass index to identify the critical pedestrian category. Different criteria to assess flood hazard have been considered, including the revised mechanics-based approach reported herein. Results from the application of the different criteria to two different case studies, namely Boscastle and Borth, showed that methods based on a full physical analysis, and which also consider human characteristics, give more insight and reliability in assessing flood hazard, especially when considering pedestrians. Results in terms of flood hazard assessments can be used to: i) design evacuation plans; ii) identify hotspots in the study area which will help with prioritisation of the adaption measures; iii) improve resilience of sites prone to flooding and plan more resilient future developments. In this regard this research work proposes a novel approach to increasing flood resilience by retrofitting existing infrastructures to enhance evacuation and access routes by reducing flood hazard rate. Results of the application of this novel methodology to the aforementioned case studies highlighted that retrofitting small portions of the existing roads can enhance iii people’s safety during the evacuation, and hence provide a cost-effective solution to improve the resilience of the existing environment