The challenges of including historical events using Bayesian methods to improve flood flow estimates in the United Kingdom: A practitioner's point of view

Abstract

Estimates of design flood flows; are important for the design of a wide variety of civil engineering structures. In the United Kingdom, the Flood Estimation Handbook (FEH) methodologies are used by practitioners to estimate flood flows. Until recently it was challenging for practitioners to include additional non‐continuous flood information, such as historical flood descriptions from historical archives, in their analyses, to reduce the uncertainty within the FEH approaches. This paper shows how Bayesian statistical methods can be applied to historical data which have degrees of uncertainty associated with then to improve design flood flows. The paper uses the River Avon at Evesham in the United Kingdom as a case study to illustrate the advantages of the method. The inclusion of historical information at this site improves the estimates of the one in 100 year flood flow compared to the values generated by the FEH pooling group method. The paper makes recommendations as to how practitioners could be encouraged to use historical flood water levels in their analysis of floods more regularly.