Siltation

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

Research on Management of Concentrated Coarse Sediment Source Area of the Loess Plateau

Abstract: 85 000 large,medium and small-sized warping dams have been built in the silt-laden and coarse sand region of the Loess Plateau.The distribution of silt-laden and coarse sand regions are more in the north and less in the south taking Wupu as the boundary and the distribution of dams and reservoirs is just contrary of more in the south and less in the north.In the northern coarse sand source region,the distribution of dams and reservoirs is less.Except the technical reasons,it also has the reasons on planning,policy,cognition and investment aspects which needs earnest study.The paper puts forward corresponding suggestions in accordance with the issues of coarse sand utilization of silt-laden and coarse sand region,dam building techniques in feldspathic sandstone region,insufficient investment,building large-scale debris-retaining reservoirs,sediment blown into rivers,siltation in a dry year and scouring in a wet year.

Ravinement en montagne: processus, mesures, modélisation, régionalisation

Abstract: Cemagref (Agricultural and Environmental Engineering Research Centre) in Grenoble and the Scientific Group "Draix, mountain erosion studies" held a conference in Digne, in the French Alps, from October 15 to 17, 2003, devoted to the theme of gully erosion in mountain areas The aims of this international seminar were to evaluate the state of the art in research on erosion by water in uplands, to allow scientists to meet and exchange ideas on related topics, and to initiate further collaborations, with particular emphasis on field work in research basins This meeting, which encompassed 32 oral presentations and 24 posters, was attended by 80 participants from 12 countries A one-day scientific excursion to the Draix experimental site was dedicated to multidisciplinary researches on mountain erosion and upland floods Gully erosion represents an important sediment source in river systems and accounts for as much as 70 to 90% of the overall sediment production of a catchment In mountain areas, the steep slopes enhance gully processes, accelerate sediment transfer from uplands to valley bottoms and generate natural hazards: mudflows, overflowing of heavily loaded floods, silting up of reservoirs, for example Therefore, there is a need for monitoring and for experimental and modelling studies in order to forecast the effects of climatic or land use changes on sediment dynamics in mountain catchments In mountain environments, the development of appropriate measurement and observation techniques is quite difficult Original devices were presented, operating from the small plot scale to the large gully and catchment scales Several presentations focused on the processes and factors controlling erosion and gullying in mountain areas: these include mechanical breakdown and chemical weathering of rocks, bed load and suspension sediment transport, in which threshold effects have a determining influence Mass movements are also a substantial source of sediments in steep upland basins These may occur as superficial earth flows affecting the weathered layer, and as deep-seated landslides or rock-block slides Several papers examined the susceptibility of the terrain to the mass movements, the conditions for landslide initiation, the relations between mass movements in black marls and rockfalls in the overlying limestone levels, and the formation and propagation of debris flows The major role of a few paroxystic events in sediment production was pointed out by several authors Particle detachment, mass movement initiation, and sediment transport are processes subjected to threshold effects The connectivity in the basin network may vary from one event to the other The studies on sediment load rates during floods showed that the availability and location of sediment stocks in the channel and gully bottoms play a greater role than the transport capacity of the flow The role of the vegetation cover in diminishing sediment yields is widely accepted Therefore, it is still necessary to understand how the aerial parts and roots of vegetation interact with runoffand erosion in order to model the evolution of gully systems subject to climatic or land use changes These studies show that erosion modelling becomes more complex as ole goes from the plot or slope scale to the catchment scale, which necessitates a transport-distance approach

Sources and trace element geochemical characteristics of the coarse sediment in the Ningxia-Inner Mongolia reaches of the Yellow River

Abstract: Siltation of coarse sediment in the river channel is the main cause of flooding and dike burst on China’s Yellow River, and the loess are thought as the coarse sediment sources of the lower reach of the Yellow River. The Ningxia-Inner Mongolia reaches of the Yellow River flow through an extensive area of aeolian desert, with flood events occurring frequently in this region. In this paper, we investigate the trace element contents of the coarse sediment in the Ningxia-Inner Mongolia reaches of the Yellow River. The main chemical components of the coarse sediments consist of 28 trace elements. Correlation analysis and factor analysis of 21 of these trace elements indicates that Ti and Zr are stable indicators of the coarse sediment sources. Comparing the spatial distribution of some of the main trace elements to major sources and riverbed sediment of the main reaches of the Yellow River suggests that the coarse sediments deposited in the Ningxia-Inner Mongolia reaches are mostly controlled by the local sediment sources. The results of R-factor analysis further proved that desert sand, riverbank material, and the Ten Tributaries are the primary sources of the coarse sediment in the Ningxia-Inner Mongolia reaches of the Yellow River.

Effect of suspended sediments on soil erodibility

Abstract: The soil erosion rate was studied on chernozemic soil samples with different densities in the flows with different contents of suspended sediments. It was shown that the soil loss was strongly reduced in the presence of suspended sediments. The reason was the silting up of interaggregate pores by sediments, which increased the forces of adhesion between aggregates and, hence, decreased the erodibility of the soil samples. An empirical equation was proposed to estimate the effect of suspended sediments on the erodibility of the soil.

Influence of Wind Force on a Silt-Muddy Coast: Huanghua Harbor Coast, China

Abstract: Huanghua Harbor, a semiclosed harbor with three 13.32–23.4 km-long breakwaters forming a coal port and a general port, is located on the silt-muddy coast of the Bohai Sea in China. Frequent gales cause thick sedimentation at the entrance and in the outer waterway. In this study, a two-dimensional depth-averaged horizontal version of the Delft3D software is used to formulate a hydrodynamic suspended sediment transport and bed evolution model. This model is validated by field data, including the tidal level, the tidal current, and the concentration of suspended sediment. The validated model is applied to predict the suspended sediment transport for three different wind scenarios and the short-term morphological evolution from a gale and a wave. The suspended sediment concentrations largely increase from gale-induced currents and waves. The predictions from the gale and its induced wave in 2003 and in 2012 indicate that suspended sediments are driven by the current along the jetties and can be easily...