Siltation

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

Storm rapid sedimentation of Maotou deep trough in the Sanmen Bay of Zhejiang

Abstract: The Sanmen Bay is frequently influenced by the typhoon, sediment exchange between beach and channel is stronger when storms hit this bay. Tidal currents are forceful with strong bottom current due to the topographic effect and predominant ebb occurs in the Maotou Channel. These features of tidal currents are a dynamic foundation to form deeper trough and to keep stability. The seabed is in the equilibrium of erosion and siltation with slight siltation in last 100 a. However, when the storms hit the bay, siltation occurs obviously in the trough and erosion in the broad tidal flat. The sediments which are eroded from tidal flat provide resources for rapid deposit in the Maotou Channel. An average depth of profile across deeper trough reduced about 142 cm measured on August 26, 1994, a week after No.9417 typhoon passed the bay. The data show that siltation strengthens from the slope to the bottom. Then the setting sediment by the storm can be resuspended and removed with the tidal current during normal weather. The depth in the trough is restored with slight erosion measured in January 1995, comparing the depth measured in June 1994. But some years, sedimentation occurred in the Maotou Trough. Three and 4 continued strong tropical storms hit the bay in 1989, 1990 respectively, they resulted in storm sediment to retain the trough. It is considered that deposited strata have stored in information of storm sediments in the deeper trough. Some "black mud" layers which contain higher water content, high organic content, low solidity and no bedding in the undisturbed core are recognized as a rapid deposit retained in the Maotou deeper trough by all previous storms.

Degradação fisica das áreas de entorno do reservatório da usina hidrelétrica Luiz Gonzaga/PE BRASIL Physical degradation of surrounding areas of the reservoir Luiz Gonzaga / PE BRAZIL

Abstract: We evaluated the relationships between physical properties of soil erosion laminar and marginal, close to the reservoir Luiz Gonzaga Hydroelectric Plant. Were listed eight areas A2, A3, A4, A11, A12, A13, A14 and A16, and the soil classified as quartzarenic neosol (RQ). The soils of the experimental areas and landslides are characterized by presenting high sand content, low amounts of clay and silt. The intensity of laminate erosion in the experimental areas was classified as zero in the small and marginal erosion landslides were classified as null and small (A2, A4, A12, A13, A16) and medium (A3, A11). The correlation coefficient between clay and fine sand (r = 0.50, p <0.05) was significant (Table 7). In general, we found a low degree of linear correlation between organic matter and clay (r = 0.45, p <0.05), organic matter and fine sand (r = 0.39, p <0.05) and clay and silt (r = 0.30, p <0.05). Thus faces the physical attributes of the units environmental fragility print, especially regarding the susceptibility to erosion and that contribute to the siltation of the reservoir in the long term.

Waterway siltation indicated by grain size distribution——Case study of Dandong waterway

Abstract: Based on the analysis of current velocity,suspended sediment concentration(SSC),and grain size suspended and bed sediments in the west channel of the Yalu River Estuary,the mechanism of sediment hydrodynamics in Dandong Waterway was studied to explore the indication of waterway siltation by grain size distributionThe results showed that the sediment source of the west channel was mainly coming from the adjacent sea area and the sedimentation was characterized by wave lifted sediment and tidal transport sedimentThe comparative analysis of the grain size of suspended and surface sediments showed that the suspended sediment deposition was the mechanism of waterway siltation in the upper and middle reaches of the navigation channels,and the bed load transport was the mechanism of waterway siltation in the lower and outer reaches of the navigation channelsThrough the analysis of the grain-size characteristics of suspended and surface sediments,channel siltation,being the indicator of sediment movement,can be used to reveal the mechanism of waterway siltationThe back-silting quantity of Dandong Waterway was 679×106m3calculated with Liu Jiaju′s and Luo zhaosen′s models,which was close to the results of physical model testAbove analysis of the silting mechanism and estimation method provided the important reference of waterway siltation research in sandy beach

Estimación de aportes sedimentarios a embalses de pequeñas cuencas mediterráneas mediante GeoWEPP. Ensayo en la cuenca vertiente del río Mula al embalse de la Cierva (cuenca del río Segura)

Abstract: The erosion and sediment yield in the Mediterranean Spanish region constitute an environmental serious problem which is mainly being studied during the last decades. Silting is, undoubtedly, an important environmental affection in the reservoirs worldwide and especially in the Mediterranean area. The sediments coming from the drainage basins are retained by dams, causing important effects on the hydro-morphological quality of channels and their aquatic ecosystems. In this study the GeoWEPP spatial erosion modeling tool is applied to evaluate the specific soil degradation in small Mediterranean basins draining water and sediment into headwater reservoirs. The basin of the river Mula flowing to the reservoir La Cierva (Segura basin) was chosen as the pilot study area, since it had enough information (e.g. bathymetric studies, sediment gauging and sedimentological reports carried out by the CEDEX) to check the model outputs. GeoWEPP integrates the simulation of the environmental processes in the basin, in a geographical information system, improving the operability to visualize, analyze and generate new information from the input data. The results (erosion rates, soil loss and sediment discharge) are represented spatially in maps showing the sedimentary contribution of each sub basin.

Sedimentation and cross-section regulation in different periods in the Lower Yellow River

Abstract: The Yellow River is famous as its excessive sediment and insufficient water. The sedimentation is influenced by the variation of incoming water and sediment and controlled by river boundaries. The dykes along the two banks can take an important role during flood events but increase the sediment silting rate of the river course. Longitudinal and transverse regulations vary with incoming water and sediment. The silting rate in the main channel is bigger than that in floodplains. In some local reaches the second suspended river are very serious. At present the withered river is caused by some water and sediment condition and the cross section will be regulated toward good condition with the advantage incoming water and sediment.