Radar-based pluvial flood forecasting over urban areas: Redbridge case study

A nowcasting model coupled with an urban drainage model is used in this study to assess the forecasting of pluvial floods in urban areas. The deterministic nowcasting model used in this paper is part of the Met Office STEPS (Short-Term Ensemble Prediction System) system, and the hydraulic model is run based on the 1D/1D dual drainage simulation scheme. A highly-urbanised catchment, Cranbrook (located in the London Borough of Redbridge), is employed for this case study to analyse the associated uncertainties. The aim of this work is to assess the impact of using rainfall forecasts with different spatial and temporal resolutions to forecast pluvial flooding over urban areas. Results show that promising performance in hydraulic forecasting is in general observed by using higher spatial and temporal resolution nowcasts as inputs; this implies the necessity of using advanced radar-based nowcasting techniques to improve the state-of-the-art pluvial flood forecasting over urban areas.