Decision support for sewer flood risk management
PublisherImperial College London
MetadataShow full item record
Flooding is an unwelcome and increasingly frequent phenomenon in many urban areas. However, as recent UK floods have shown, serious inundation can still occur even if river discharge has not exceeded the functional flood plain capacity due to 'pluvial' or sewer flooding. This work focuses on sewer flooding and its management. The aim of this study is to develop a methodology to support effective sewer flood risk management within a decision support framework, based on a sound understanding of the urban flooding regime. An urban drainage modelling tool was used to generate a flow time series based on long-term continuous rainfall inputs (rather than individual storms). A catchment delineation method was applied on a detailed digital elevation model to predict the extent of flooding and flood stages were assigned to the different flood discharges at each property in a catchment. A flood risk model was developed to assess flood risk in terms of probability and consequence. Flood probability was identified using statistical analysis for the flood stages, and flood consequence was obtained from the relationship between the flood stage and the corresponding damage cost. Annual average flood risk for each property was identified by linking the flood probability, stage and damage. A decision support framework was developed to allow the rational comparison of different management strategies ranked in terms of highest cost benefit difference or benefit cost ratio. This was used to compare a wide range of different sewerage rehabilitation and management scenarios in terms of flood costs and benefits for a particular case study. The wider application of the framework was demonstrated.