Application of time-of-day and day-of-week-based hazard in dam break assessments

The consequences of failure for dams upstream of urban areas are usually considered to be severe, which can be reflected in a detailed hazard assessment as part of a dam break mapping exercise. These urban areas are usually populated with differing types of commercial and residential properties, all of which have different usage and occupancy both throughout a typical day and over a typical week. This study details a case study for a UK reservoir dam break model and documents – and discusses the differences between the often-adopted time-averaged values of population at risk and average societal loss of life, and an alternative proposed time-of-day and day-of-week consequence assessment technique. The study makes use of detailed two-dimensional hydraulic modelling techniques, and occupancy data from online application programming interfaces and other mass data collection surveys. The ramifications of the additional detail provided by the alternative approach are discussed and contextualised.