Are the Benefits of Integrated Catchment Modelling Being Realized in the United Kingdom?

Historically, hydrological systems have been modelled separately to investigate flood risk. This is due to computational limits and the devolved responsibilities set out in the existing legislation for risk management authorities. This method may result in the true impact of flooding being misrepresented as the interaction between hydrological systems and drainage infrastructure unaccounted for. In contrast, integrated catchment modelling (ICM) is a methodology in which various hydrological systems are explicitly represented in a single flood model. This enables more realistic assessments of flooding sources and mechanisms, and allows for improved communication of risk. This article provides an overview of the use of ICM in the UK; discusses the benefits of and barriers to the use of ICM; and provides case studies that demonstrate the benefits of ICM for multiple end users. Cost–benefit analyses are traditionally carried out using results from separate models, and alleviation schemes are developed and funded based on the outcome. The economic benefits may be underestimated and the scheme under-designed due to inaccuracies inherent in separate modelling approaches. The use of ICM allows for the development of flood alleviation schemes (FASs) that provide multiple benefits by protecting people, properties and infrastructure at risk from combined sources of flooding. As set out in the Flood and Water Management Act 2010, Lead Local Flood Authorities (LLFA) are responsible for strategic flood risk management and as a result are moving towards the use of ICM to open more funding streams for FAS development. ICM provides a tool that demonstrates to multiple stakeholders how they can benefit from a single alleviation scheme. This increases the chances of a scheme reaching construction due to greater funding potential. While there are still barriers to the use of ICM, the benefits are beginning to be realized by LLFAs and other regulatory bodies.