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This paper presents an overview of a study on salinity intrusion through shiplocks that are located at a saltwater and freshwater interface, and the possible measures that can be taken to reduce this salinity transport. The main focus of the study was to test the effectiveness of several measures against salt intrusion through a shiplock. For this reason a series of field experiments was conducted in the Stevin shiplock in the Afsluitdijk, near Den Oever, the Netherlands, in between the Wadden Sea and the IJsselmeer. The measures tested include an air curtain at both ends of the shiplocks, alone and in combination with a water jet, as well as a rigged sill to reduce the effective depth, and flushing of the lock with fresh water. A new type of air curtain with air injectors was designed and built for this study. Prior to the field experiments, a series of laboratory scale experiments and computer simulations of lock-exchange flow were conducted to gain insight into the salinity transport process and to support the design of the field study. The study has shown that a significant reduction of salinity intrusion can be attained by using a combination of measures. These findings are relevant for shiplocks located in a saline–freshwater transition zone for which salinity intrusion should be reduced as much as possible. Copyright © 2011 John Wiley & Sons, Ltd. RESUME Ce document presente un apercu d'une etude sur l'intrusion de la salinite a travers les ecluses maritimes qui sont situees a l'interface eau salee/eau douce, et les mesures possibles susceptibles d'etre prises pour reduire ce type de transport de la salinite. L'objectif principal de l'etude etait de tester l'efficacite de plusieurs mesures contre l'intrusion du sel par une ecluse maritime. Pour cette raison, une serie d'experiences a ete menee dans l'ecluse maritime Stevin dans l'Afsluitdijk, pres de Den Oever, Pays-Bas, entre la mer des Wadden et l'IJsselmeer. Les mesures testees comprennent un rideau d'air, seul et en combinaison avec un jet d'eau, ainsi qu'un seuil pour reduire la profondeur efficiente, et le rincage de l'ecluse avec de l'eau fraiche. Un nouveau type de rideau d'air avec des injecteurs d'air a ete concu et construit pour cette etude. Un rideau d'air a ete installe aux deux extremites de l'ecluse maritime, avec un systeme d'injection d'eau douce (a cote de la mer des Wadden) et un seuil (sur le cote IJsselmeer). Dans une serie d'experiences il y avait aussi un flux constant d'eau douce a travers l'ecluse. Les mesures sur le terrain ont ete menees dans la periode avril-mai 2010. Avant les experiences de terrain, une serie d'experiences en laboratoire et des simulations par ordinateur des flux d'echange des eclusees, avec et sans mesures de reduction de l'intrusion de la salinite, ont ete menees pour mieux comprendre les processus de transport de la salinite et de soutenir la conception de l'etude sur le terrain. L'etude a montre qu'une reduction significative de l'intrusion saline peut etre obtenue en utilisant une combinaison de mesures. Ces resultats sont pertinents pour des ecluses situees dans une zone de transition saline-eau douce, pour laquelle l'intrusion saline devrait etre reduite autant que possible

A numerical model is presented for the simulation of wave- current driven sediment transport and it is developed as research tool. In line with previous papers (Uittenbogaard 2000, Bosboom and Klopman 2000) the present paper validates its applicability as a research tool improving sand-transport formulations. This paper compares the Stokes drift derived from laboratory experiments with the numerically simulated Stokes drift. Further, two analytical test cases are included, one for sand transport in steady flow and a second case for oscillatory bed concentration. Based on a sensitivity analysis, we recommend other researchers to also validate their sand-transport models against these analytical test cases.

In natural water flows, horizontal vortices with scales exceeding the water depth contribute significantly to bed stresses as well to the lateral exchange of momentum and matter. In these flows horizontal 2D turbulence is subjected to bed friction as well as to a mobile water surface.This paper investigates whether our standard shallow-water solver Delft3D-Flow can simulate the properties of quasi-2D turbulence as observed in the free-surface mixing-layer experiments of Uijttewaal Booij (2000).