Laboratory observations of the morphodynamic evolution of tidal channels and tidal inlets

This paper tackles the problem of morphodynamic equilibrium of tidal channels and tidal inlets. We report a laboratory investigation of the process whereby an equilibrium morphology is established in a tidal system consisting of an erodible channel connected through an inlet to a tidal sea. Observations suggest that a morphodynamic equilibrium is eventually established both in the inlet region and in the channel. The latter exhibits a weakly concave bed profile seaward, a weakly convex profile landward, and the formation of a “beach” close to the landward end of the channel. A second set of observations concerns the formation and development of both small‐ and large‐scale bed forms. In particular, small‐scale forms are found to develop in the channel and in the basin, while larger‐scale forms, i.e., tidal bars, develop in the channel. A last observation concerns the formation of an outer delta in the “sea” basin. Results concerning the long‐term equilibrium of the bed profile in the channel compare fairly satisfactorily with recent theoretical results. The nature and characteristics of the observed small‐scale forms appear to be consistent with theoretical predictions and field observations concerning “fluvial” ripples and tidal dunes; bars show features in general accordance with recent results of a stability theory developed for tidal bars. The hydrodynamics of the inlet region exhibits a strongly asymmetric character, as observed in the field and predicted in early theoretical works, while the overall characteristics of the outer delta conform to available empirical relationships.