Author(s): J. Vercruysse; K. Verelst; T. De Mulder
Keywords: No keywords
Abstract: Within the framework of the Updated Sigmaplan, Flood control Areas (FCA) with a Controlled Reduced Tide (CRT) are set up in several polders along the tidal section of the river Scheldt and its tributaries. The reduced tide is introduced by means of simple inlet and outlet sluices located in the levee between the river and the polder. In recent designs, the inlet sluice is placed on top of the outlet sluice. At water intake, the water drops from the brink of an inlet sluice apron into a stilling basin, integrated with the floor slab of the underlying outlet sluice. Flanders Hydraulics Research performed a scale model based review of several desktop designs of this type of combined inlet and outlet structures. This paper compares the scale model results and predictions of literature formulae for drop structures and stilling basins, upon which the desktop designs were based. Several types of sluice geometries–with a straight stilling basin, a locally deepened stilling basin and a stilling basin with baffle blocks–were studied. This comparison exercise concludes that suitable formulae are available for a stilling basin design when the tailwater depth at the polder side equals the conjugate water depth. For higher tailwater depths, no suitable literature formulae seem to be available and physical (or numerical) modelling is recommended.