Investigating hydraulic operational schemes of a large-scale multi-lane lock group concerning water-level fluctuations in a branched approach channel system

Water-level fluctuations in a branched approach channel system exert significant impacts on the operation of navigation structures. This study takes a multi-lane lock group located downstream of the Three Gorges Dam as an example, the spatiotemporal variation patterns of maximum amplitude of water-level fluctuations in a branched approach channel system are revealed based on shallow water model validation, we then investigated the operational modes of a quadruple-lane lock group regarding risky navigation at the lower lock head of the ship lift. Results demonstrate that: (i) effects of initial water surface elevation and base flow during the dry season on the amplitude of water level variations are greater than during the flood season; (ii) maximum water-level fluctuation primarily occurs at the lock heads, with the lock head of the ship lift being the critical concern site where the maximum hourly variation in water level is approximately twice that at the entrance under the simultaneous operation of locks; and (iii) intervals of locks operation longer than 4 min are more conducive to the safe navigation of the ship lift. Conclusions acquired in this study may provide a guidance for controlling water-level fluctuating amplitude during a safe docking scenario of a ship chamber.