How to illuminate the twilight world of engineering hydrology

In the words of David Sellars, engineering hydrologists ply their craft in the twilight, always looking for a shaft of illumination to enhance their understanding. Many decisions on flood risk management around the world are made using techniques that hydrological scientists would barely recognise. The Rational method, first formulated in 1850, is still widely used for design of structures, despite the availability of more scientifically justified alternatives. Software packages used by practitioners offer a variety of modelling techniques, sometimes without any guidance on their validity. It is common to see uncritical application of infiltration equations at a catchment scale with no acknowledgement that they ignore preferential pathway flow. There is a responsibility on both practitioners and software developers to improve scientific understanding.

Meanwhile, research projects and programmes, even with an operational focus, can produce reports, papers and even new techniques that never influence any engineering design, planning decision or operational forecast. In the UK, research into national flood frequency estimation by continuous simulation was completed in 2005 but has seen little implementation. One barrier was the decision to generalise rainfall-runoff model parameters using catchment properties which were not readily available to practitioners. Other UK initiatives have been more successfully adopted by practitioners, including recent development of guidance and tools for non-stationary flood frequency estimation. This produced a software tool that could be applied with a basic knowledge of the R language, along with practitioner-focused guidance, all freely available to download.

As an alternative to regulators trying to impose new approaches, a more promising avenue for implementation of research could be to create an environment in which the practitioner community is encouraged and incentivized to innovate, seeking out shafts of illumination from academia.