Siltation

About: Siltation is a research topic. Over the lifetime, 1420 publications have been published within this topic receiving 20983 citations.

Overview of siltation downstream estuarine floodgates

Abstract: Constructing sluices is widely used as an important way of estuarine regulation in China,which will lead to severe siltation downstream estuarine floodgates while promoting the local economic development and limiting the comprehensive use of estuary.This paper describes the siltation downstream sluices and elaborates the silting mechanism and simulation study at home and abroad on this problem.Many factors influencing the siltation pattern are summarized including the tidal current,the length of irrigation channel,dynamic features of estuarine sediment,the types of rivers downstream sluices,location of sluices,etc.The defects existing in the previous study are illustrated and suggestions are given to the direction and methods of future study.

Seepage siltation test device for earth

Abstract: The utility model relates to a seepage siltation test device for earth. A water-outlet base drum, a material containing drum and a water inlet top drum are installed on a test tower support. A hole water pressure detecting hole is arranged on the lateral face of the material containing drum, a hole water pressure sensor is installed in the hole and is connected with a computer, a three-way valve structure formed by a siltation test material container pipe, a return water control valve, a feeding inlet valve and a water delivery valve is installed at the upper end of the water inlet top drum, and a high pressure water tank is formed by a water supplying pipe and a water pump in a water collecting tank. The test device for seepage siltation of the earth feeds siltation test materials under the condition of continuous water supply, achieves the continuous process of a seepage siltation test, changes a measurement method of an existing pressure measurement pipe, utilizes multi-section seepage electronic monitoring recording and data processing, can visually reflect interrelationship between particle size, hole water pressure and seepage flow, solves the problem of influence on observation of permeability of loose media under the condition of siltation effect, and provides reliable scientific data for large engineering design.

Effects of a current deflection wall in a tidal harbour entrance

Abstract: Siltation as a serious problem in harbours situated on tidal rivers and estuaries causes maintenance dredging or needs other measures, to guarantee safe navigation and is often a large cost factor. To prevent sedimentation of fine materials entering a harbour, Current Deflecting Wall (CDW) can be used, which passively alters the water exchange. This paper presents a numerical experiment on the effects of a CDW to reduce siltation in harbours. The experiment was designated to investigate the effects of a CDW on water exchange and turbulent mixing in the transition area between river and harbour basin, and thus reproduce results of previous physical experiments. The investigated CDW for inhomogeneous conditions covers the top half of the water depth, capturing water during the main part of the flood period in order to slow down outgoing density currents through the upper layer. A sill at the bottom deflects the near-bed density current away from the entrance. This creates a vertical vortex with its axis across the entrance during rising tide, which reduces near bed water influx coming from the river bed. As a conclusion the exchange during rising tide originates from the upper layer, which is less dense and contains less sediment. The effect of the Current Deflecting Wall described by VAN LEEUWEN and HOFLAND (1999) were not reproduced. The stated complex and constant eddy structure over the whole entrance (Fig. 9.10, p. 78) was not visible in this experiment. The experiment showed, that water exchange, and thus sediment input, between river and harbour entrance in an inhomogeneous (brackish) environment can be reduced to a certain extent. CDWs cannot prevent the density driven current. However, a substantial reduction of siltation should be possible.

Sediment transport pathway within the North Branch,Changjiang Estuary

Abstract: The surface sediment samples were collected in the North Branch to obtain the grain size and heavy mineral data sets in September,2007.The grain size trend analysis model developed by Gao and Collins(1992) has been applied to obtain the sediment transport pathway in the study area.The results show that the sediments transport towards the down stream from the upper entrance and towards the upper stream from the mouth.In addition,the sediments also transport into the North Branch from the adjoining sea area.The variations of the ration of stable and unstable heavy mineral contents show that sediments converge within the North Branch,which has been supported by the sediment dynamics measurements and geomorphology changes.The net deposit in the North Branch has resulted in the significant siltation.