Water level measurements, direct discharge measurements (gaugings) and rating curves constitute an indirect way for continuously estimating river discharge. Discharge data are used in many applications such as flood forecasting or the sizing and operation of infrastructure that directly concerns people’s safety. It is therefore extremely important for the data users to know the quality of discharge series. Field hydrologists must express the uncertainty associated with each step in flow computation: stage measurements, gaugings, tracing of the rating curves, and finally the uncertainty on the streamflow series. Innovative hydrometric methods, like non-intrusive techniques (Radar, or LSPIV), can allow improved discharge measurement (during high flow for example) and so improve the quality of streamflow series. The uncertainties of those methods need to be evaluated as well.

The aim of the proposed session is to give field hydrologists the opportunity to demonstrate how important the uncertainty of streamflow series can be by showing the uncertainty of each step of their construction (water level measurements, gaugings, tracing of the rating curves…). By presenting new technologies, sensors, ways to build the rating curves and case studies taking into account the idea of uncertainty, the goal of such a session is to show that streamflow data series are sometimes far from accurate and to highlight methods for assessing that uncertainty.