Practitioner perspectives of Flood Source Area (FSA) analysis for system-based flood risk management

Urban Flood Risk Management (FRM) is a critical aspect of developing resilient environments for future generations to inhabit. It is now interconnected with the requirement to be more environmentally conscious through blue-green infrastructure and the delivery of wider co-benefits. The complexity of balancing urban growth with environmental drivers and increasing resilience is a key challenge for strategic urban decision-making. Through computational modelling developments, new approaches to assess the spatial contribution of area to flood hazard are improving our understanding of the catchment response and our ability to develop multifunctional, multi-beneficial projects. Yet at present, these approaches remain largely theoretical or are a ‘best intention’. This study uses an adapted ‘Unit Flood Response’ approach to generate Flood Source Area (FSA) maps for an urban catchment in the UK. A user-focused engagement approach is applied using FSA outputs to generate key insight into its applicability from a practitioner perspective. The FSA modelling identified several hazard sources, from widespread contributions upstream to discrete contributions downstream. Stakeholders concluded that the FSA can support FRM at the pre-planning stage by providing a clearer strategic vision across the catchment to support traditional ‘receptor-led’ decision-making. Improved identification and negotiation of project partners and the potential to support/identify wider scale options that integrate with existing and planned infrastructure in other sectors, for example, housing and transport, were additional benefits of this approach. While the computational aspects of FSA analyses could be improved for model robustness (e.g., calibration, validation), they must do so with a full understanding of the practicalities of applying these techniques on the ground, demonstrating the importance of co-development of research with practitioners and decision-makers.