Framework for assessing uncertainty in fluvial flood risk mapping

This guide provides a framework for good practice in assessment of uncertainty in fluvial flood risk mapping. The starting point is the position that all uncertainty assessments needs to involve subjective judgements because clarity and transparency in expressing and agreeing those judgements is imperative. The framework for doing so is a series of steps covering consideration of the range of uncertainties in data and modelling, together with the choices for presentation and visualisation of the resulting flood risk mapping. Ideally, the process of working through the steps should be undertaken as a joint exercise including the modeller/analyst and representatives of the end users of the flood risk mapping. The decisions on how to assess the uncertainty should be agreed and recorded for future reference. Part of a suite of four CIRIA guides (C717, C719, C720, C721).