The introduction of the entropy concept in hydraulics by Chiu gives the possibility to develop a simple method to measure discharges in natural streams. The application of this method on four streams in north Algeria made a possibility to develop a linear mean-max velocity models, deduce the entropy parameters and the cross sectional areas expressions for all streams in order to obtain the water discharges easily with minimum errors. The Chiu's velocity distribution equation was also checked for a large range of discharges, water levels, and flow pattern, where it proves its efficacy.

Flow velocity measurements using point-velocity meters are normally obtained by sampling one, two or three velocity points per vertical profile. During high floods their use is inhibited due to the difficulty of sampling in lower portions of the flow area. Nevertheless, the application of standard methods allows estimation of a parameter, α, which depends on the energy slope and the Manning roughness coefficient. During high floods, monitoring of velocity can be accomplished by sampling the maximum velocity, umax, only, which can be used to estimate the mean flow velocity, um, by applying the linear entropy relationship depending on the parameter, M, estimated on the basis of historical observed pairs (um, umax). In this context, this work attempts to analyze if a correlation between α and M holds, so that the monitoring for high flows can be addressed by exploiting information from standard methods. A methodology is proposed to estimate M from α, by coupling the "historical" information derived by standard methods, and "new" information from the measurement of umax surmised at later times. Results from four gauged river sites of different hydraulic and geometric characteristics have shown the robust estimation of M based on α.

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