Interactions between pluvial and fluvial floods in floodplains in Lower Wortley, Leeds, UK

Heavy precipitation with unplanned land use can alter the catchment response time; thus, natural processes of floods can be affected. As a result, floods from multiple sources can be observed concurrently or consecutively at the same location. However, the location-dependent interactions between floods and the consequences of flood combinations have not been studied sufficiently. This research examined the interactions and the consequences of combined floods occurring on the settlements on floodplains along urban streams in an ungauged and urbanized catchment. The flood extents, merging from the river overflow and the rainfall-induced runoff, were simulated directly for Lower Wortley, Leeds, UK. The study demonstrates that an assessment of the floods occurring from multiple sources at the same location is necessary to improve flood risk management approaches, because the merger floods could significantly increase the impact of any single flood, and so the flood defences become deficient.