5-7 October 2020
Europe/Berlin timezone

How can the uncertainty in indirect estimates of extreme flash flood discharges be reduced?

7 Oct 2020, 11:20


Oral presentation Flash Flood Prediction


Darren Lumbroso (HR Wallingford)


Direct current meter measurements are rarely available for extreme flash floods. Corresponding discharges are generally estimated using so-called “indirect” techniques such as the slope – area method. These methods are based on empirical hydraulic formulae that typically use Manning’s equation, and have been calibrated and also widely tested for flow conditions that differ significantly from those encountered during flash floods. Recent work conducted in Europe, as part of the HYDRATE research project and other studies, has shown that the use of these formulae and their associated tabulated roughness values available in current guidance documents, without further verification, can lead to over-estimates of peak discharges in the case of flash floods. After having discussed the limitations of indirect methods based on Manning’s formula, the presentation describes how the uncertainty in indirect discharge estimates can be reduced through the analysis of various types of data that can be collected during post-event surveys and through consistency checks. Based on a review of current literature and on recent flash flood studies, we suggest simple guidelines to assist practitioners in estimating extreme discharges during post-event surveys.

Primary author

Darren Lumbroso (HR Wallingford)


Eric Gaume (IFSTTAR)

Presentation Materials

There are no materials yet.
Your browser is out of date!

Update your browser to view this website correctly. Update my browser now