Design Of A Smart Sand Trap Construction As APart Of An Interregional Environmental Study

Abstract

The Mark-Vliet river system transports bed material and heavily polluted suspended sediments to the Volkerak-Zoom lake. To protect the living, working and recreation areas in this catchment, a proper integrated water management is essential. A systematic control and sanitation of the polluted sediments in the river environment will help to stop the further degradation of the water system quality. Therefore, a transboundary collaboration between Belgian and Dutch authorities is set up to study and sanitate this interregional river catchment. To improve the water and river bed quality, an effect-oriented as well as source-oriented approach is followed. The inventory of pollution sources is translated into a sanitation plan for the competent authorities. The effect-oriented approach searches an optimum design and location of sand trap configurations in the catchment. As pollutants are mainly fixed to the fine suspended material, it is valuable to separate the relatively clean sand particles from the heavily polluted fine fraction. Hence, the amount of polluted (silt and mud) dredged material and consequently the treatment costs are reduced. Starting from an existing sand trap configuration, an adapted construction is designed through physical scale model tests taking into account the practical and economical issues of the project. The operation of the optimum sand trap configuration relies on three basic principles: an upstream bifurcation ensures a proper deflection of suspension transport in a parallel deviation; a downstream sill controls the flow distribution over the respective main and deviation branch for different regimes; an underwater sill at the entrance of the lateral deviation forces the transport of all sand material near the bottom into the sand trap. Transactions on Engineering Sciences vol 9, © 1996 WIT Press, www.witpress.com, ISSN 1743-3533