Entropy Theory Application for Flow Monitoring in Natural Channels

A quick and accurate determination of flow passing through a river section is fundamental for a large number of engineering applications such as flood forecasting models and the real time water resources management. Velocity is one of the basic variables for open channel flow and its variation across a section is described by the velocity profile distribution. This aspect has been also investigated through a probabilistic approach based on the entropy concept, which also expresses the mean flow velocity as a linear function of the maximum velocity through a dimensionless entropy parameter M. Therefore, the entropic relationship between the mean flow velocity and the maximum velocity has been investigated here for nine gauged river sections. Five of them are located in Italy and the other four in Algeria. Based on the flow velocity measurements sample of each site, the robustness of the linear entropic relationship has been proved. The entropic parameter, M, which characterizes the relationship, has been found uniform for seven river sites with a value in the range of 2.1 – 2.5. For two river sites the value has been lower and equal to -0.22 and 0.33, respectively. As this parameter is fundamental for addressing the flow velocity measurements at equipped river sites, the morphological characteristics of river reaches where the gauged sections are located have been investigated and identified in terms of Rosgen classification. The seven gauged sections with uniform M value have been found belonging to the same stream classification, i.e. type C, except one located in Algeria which is type D. The other two with different M values have been ascribed at different types. The analysis, although preliminary, allows foreseeing new developments in the application of the entropy approach addressed to quantify high flow discharges, especially in new gauged river sites where M is unknown.