Siltation

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

Siltation characteristics of the 12.5 m deepwater navigation channel in Yangtze estuary

Abstract: A series of dredging and hydrologic data in situ measurement are collected to study temporal-spatial variation characteristics of siltation,and the dependency relationship of siltation on riverine discharge,tidal range and local suspended sediment concentration in the 12. 5 m Deepwater Navigational Channel( DNC) in the Yangtze Estuary. The results show that: ① the quantity of siltation in DNC is much greater in flood season than that in dry season; ② the sedimentation during storms is very serious; ③ the deposited sediments mainly distribute in the South Channel— Yuanyuansha Channel and the middle reach of the North Passage; ④ the grain size of the dredged sediment in the upper reach is greater than that in the lower reach; ⑤ the quantity of siltation in the South Channel—Yuanyuansha Channel is no sensitive to the riverine discharge,but it deposits more during spring-tide and less during neap-tide; ⑥ the central position of the siltation in the North Passage varies with the intensity of discharge,when the discharge becomes small,it move up-estuary,and vice versa; the quantity of siltation in the North Passage will get greater in flood season than in dry season; ⑦ the resuspension of the deposited sediments near the estuarine turbidity maxium area is the main contribution to the siltation in the dredged navigational channel.

Sedimentation in small dams. Estimating the impact of catchment conservation, check dams and sediment bypassing in reducing dam siltation rates

Abstract: The British Government's Department for International Development commissioned HR Wallingford to carry out a study to develop guidelines presenting appropriate methods for predicting, and where possible reducing, siltation rates in small communal dams in semi-arid zones in Eastern and Southern Africa. Small dam designers must be able to use these methods; they need simple procedures to carry out assessments rapidly, may not have software skills or computers, and may only have access to very limited local data. A capability to estimate the impact of measures to reduce small dam sedimentation rates is needed to enable the sedimentation lifetime of dams to be estimated at the planning and design stage of small dam projects. This report describes approximate methods for carrying out these calculations. The measures considered are check dams, soil and water conservation measures and sediment bypassing.

Site test of siltation for foundation trench of immersed tunnel of Hong Kong-Macau-Zhuhai Bridge

Abstract: The studies used a test foundation trench to carry site measurement of siltation of Hongkong-Zhuhai-Macau Bridge. A test foundation trench which was 100-meter-long and 21-meter-wide was excavated near the west artificial island. The medial axis of trench was consistent with the designed axis of immersed tunnel. The data of 12-month site measurements indicates siltation happened on trench bottom and surface of trench slopes. North slope is more obvious than south slope. There was no obvious siltation on east and west slope. It has little chance that serious siltation happens on foundation trench of immersed tunnel after storm surge.

Numerical Simulation of Current Field in the North and South Channels and Hengsha East Shoal with the Effect of Some Important Projects, Yangtze Estuary

Abstract: Adopting staggered grid C and ADI method, Delft3D-flow was applied for the purpose of studying the effect of the Deep Channel Project and Hengsha East Shoal Siltation Promotion Project through numerical simulation, the results of which could provide scientific demonstration on the feasibility study of siltation promotion projects 

CONTRIBUTION DU SIG A LA RECONSTITUTION DES PROCESSUS DE PROGRADATION DE LA MAJERDA : quels enjeux pour le port d'Utique?

Abstract: The Majerda delta formation has been the subject of many studies since the late XIXe century. The reconstruction of the fluvial palaeo-environments of the lower Majerda valley is significant as it is critical to understand the decline of Utica following the siltation of the harbor, which is presently buried under sediments. The progression of the delta across the corridor separating the Southern and the Northern compartments of the ancient Utica bay is the cornerstone of our research on the delta. On the basis of a GIS we propose to identify hydro- and morpho-sedimentary processes of the deltaic progradation dynamics. They lead to innovative ways of considering the initial implantation site of Utica, the conditions of harbor siltation and the Majerda River itself across the Northern compartment. Observations and analysis from the GIS allowed highlighting a double system of alluvial fans over the whole delta. The first component which may be described as “torrential” is present throughout the delta fringe, while the second category of flat alluvial fans occurs at the Majerda defluviation sites, forming coalescing alluvial lobes. The ancient merging of these two morphological systems close to Utica could reflect a process of harbor silting more complex than previously considered, the Majerda River being considered as the unique factor of change so far.