Closure to “Unsteady Stage-Discharge Relationships for Sharp-Crested Weirs” by Firouz Ghasemzadeh, Salah Kouchakzadeh, and Gilles Belaud

International audienceThe discusser is highly acknowledged for his interest in the paper and for presenting valuable analytical work to highlight the deviation between steady and unsteady flow rate of an orifice installed at the invert of a tank. A majority of previous related research studies, as mentioned in the original paper, claimed that the steady-state rating curve of sharp-creased weirs could be used in unsteady flow. Accordingly, the main objectives of the original paper were (1) to highlight the deviation between the stage-discharge curve of the two flow conditions, and (2) to report and justify the transposition of the looped stage-discharge curve in the weir flow condition compared to that typically observed in streamflows.The discusser, by developing an analytical solution for his studied case, agreed to the first point raised by the authors, which indicates the importance of studying the impact of unsteady flow conditions on discharge measurements, which calls for further studies. However, the transposition of the stage-discharge in the looped curve, i.e., the second point, has not been observed in the discusser’s work. The writers believe this could be attributed to the fundamental differences between the two studied cases as discussed herein