Scour and silting characteristics downstream of tidal barriers in muddy estuariesand their analytical forecast

Studies on scour and silting characteristics downstream of tidel barriers in muddy estuaries show that the sole condition for siltation downstream of tidal barriers in waterways is the amount of sediment held by flood currents which should be greater than that by ebb currents. The hydrodynamic causes resulting in siltation downstream of tidal barriers are the decrease of runoff and the deformation of tidal waves. In this paper, based on the analysis of mechanism of siltation downstream of tidal barriers, it is put forward that for construction of tidal barriers and of those combined with guiding jetties, the tideabsorbingforsiltation method and the bed equilibrium method should be used for their analytical forecast, and that for scouring depth on the top sand barrier areas by channel narrowing and sediment training between jetties, the analytical forecast can be realized considering tidal inlets, hydraulic geometry of river channels, bed equilibrium and hydraulic characteristics, in accordance with the practical hydrodynamic conditions. The above two ways of analytical forecast have been proved useful by some measured data of relatied projects and results of physical model tests.