Validation of indirect discharge estimation in open channels by means of lab experiments

A novel methodology for simultaneous discharge and channel roughness estimation, based on unsteady state water level data analysis, has been recently developed. The methodology is based on the synchronous measurement of water level data in two river sections far some kilometers from each other, as well as on the use of a numerical flow routing solver and does not require any direct velocity measurement. In the present paper, the proposed methodology has been validated with the results of laboratory experiments carried out at the Polytechnic of Bari University (Italy). A known discharge hydrograph has been delivered in the upstream tank of a rectangular flume, where two water level sensors had been located 7.92 meters from each other. A third water level sensor located above the tank has been used to “measure” the discharge hydrograph entering in the first section of the flume, given the known one and the horizontal section of the upstream tank. The flume had a very small slope, equal to 0.0006. Two different bed materials have been used, corresponding to very different roughness coefficients. Eight “measured” discharge hydrographs have been compared with the hydrographs computed using both a diffusive and a fully dynamic model. Criteria for the choice of the flow routing model are finally given, based on the match between the “measured” and the computed discharge hydrographs in the experimental runs.