Sediment Movement Characteristics Research Articles

Study of the recent sediment movement features in the vicinity of Deepwater Navigation Channel, Yangtze estuary

Intensive anthropogenic impacts have been implemented in the Yangtze estuary during the last several decades, which significantly modified the global and local hydro- and morpho-dynamics. Subsequently, sediment movement characteristics in the vicinity of the Deepwater Navigation Channel (DNC) change in accordance with such human interactions. The present study is focusing on the recent sediment moving features around the DNC in between 2017 and 2019, after the elevation of the partition dike in 2016. Five successive in-situ regular campaigns for flood and dry seasons, together with field surveys pre- and post-typhoon in 2018, were conducted to collect bottom surface sediment samples. Sand and silt samples with different physical properties were identified. Under the normal weather condition, sand samples are generally found in the South Channel (SC) and the middle reach of the North Passage (NP), whereas silt samples are prevailed elsewhere. Considering the different features in the grain size distribution curve of sand samples, more attentions were paid to the spatiotemporal variations of sand samples. Grain size parameters of sand samples indicate that under the normal weather condition, relatively pure sands with almost no silt constituent exist in the SC, whereas relatively mixed sands with certain silt compositions are located in the middle reach of NP. Nevertheless, only relatively mixed sands could be found in the SC and there are no sand samples in the NP after typhoon events. Subsequently, the recent sediment movement characteristics in the vicinity of DNC were figured out. Under the normal weather condition, relatively mild siltation owing to the back-filings from the dike fields and seaward of DNC occurs in the middle and lower reaches of DNC, which is consistent with the temporal variations of the magnetism analysis of sand samples. In contrast, intensive siltation occurs inside the DNC after the extreme weather events, which comes from three possible provenances, i.e., overtopping from the south dike, back-fillings from dike fields and seaward of DNC. These findings provide some helpful information for the efficient management and reasonable regulation in the Yangtze estuary.

Discussion on Some Problems of Local Scouring of Bridge Foundation

Local scouring is one of the main factors leading to bridge foundation damage. There are many aspects involved in the study of local scouring of bridge foundation. In this paper, the research progress of flow structure, sediment movement characteristics and evolution characteristics of scour pits in pier local scouring are summarized. The influencing factors of pier local scouring are concluded. Finally, the existing problems and future research trends are discussed.

Calculation on the Settlement of Two Sands

Sediment settling velocity in the water is a sign of important physical quantities of sediment movement characteristics. Sediment concentration has a significant impact on the settling velocity. On the one hand,in the process of settlement,Single particle of sand would arose the movement of circumambient water. Because of the existence of other sand, circumambient water is blocked and loses the freedom of movement. Its equal to increase the water viscosity. And this makes the settling velocity lower. On the other hand, sand in the process of settlement brings along the circumambient water, and that goes with the sand down, and this makes the settling velocity bigger. Moreover, the existence of lots of sands will augment the turbid water density, and increase the buoyancy of every sand and finish its settling velocity. This paper states and trims the experiment data of the yellow soil at Station Hua yuankou and Fly-ash in Zhengzhou Power Plant, Using the Robertss experiential formula and Kynch experiential formula, the turbid water thickness and the time it needs are computed. After contrasting of the computed results, we have known that the laws which Fly-ash follows better than the silt.

Sediment movement characteristics of coast and analysis of seabed evolution

The rotary ring flume is used to study the silty sand movement in a periodic alternating current. Characteristics of sediment movement of different coasts in the tidal current are summarized. More detailed analysis of erosion-sedimentation function in a numerical simulation is made. The equilibrium sediment concentration is advanced. Based on the equilibrium sediment concentration, the seabed erosion-sedimentation index is derived and the seabed erosion-sedimentation calculation is analyzed. The seabed erosion-sedimentation index is used to calculate the seabed evolution of Yangshan sea area and a good agreement with field measurements is obtained.

Study on the Macro-scale Sediment Movement Characteristics based on Feldspar Thermoluminescence Features

Investigation on the sediment movement characteristics in a broad area with a 150 kilometer stretch along the Enshunada Coast and the Suruga Bay was conducted based on feldspar thermoluminescence (TL) properties. River sand grains (primary source) present a higher TL signal than beach sand. Along the nearshore area, local TL intensity peaks are observed at the river mouth and the intensity gradually deceases with increasing distance from the river mouth, which indicates longshore transport features. Taking the spatial distribution of TL intensities into account, a quantitative estimation on the longshore sediment flux was carried out based on the total river sand discharge.Identification of coastal sand source was achieved in terms of the profile and magnitude of the measured TL glow curves.

Experimental Study on Sediment Movement in a Channel with Model Reef

An artificial beach has been constructed in coastal region facing to a coral reef. To prevent beach erosion, characteristics of sediment movement on the beach should be investigated in flume experiments. The watervelocity becomes very large with wave breaking zone on the reef. Therefore, the critical amplitudes of velocity on reef should be defined for the promotion of beach protection methods. The-experiment results demonstrate that the critical velocity is related to the shields number.

Mississippi River Shoaling: A Diagnostic Study

The field study was conducted to collect definitive data on the flow and sediment movement characteristics in the recurrent shoaling reaches of the Mississippi River in the vicinities of Fox Island (RM 355-6) and Buzzard Island (RM 349-50) in Pool 20 between Keokuk, Iowa and Canton, Mo. The detailed field data were used to identify the source of the excess sediment input into the Mississippi River, and to elucidate the principal mechanisms of shoaling processes in the study areas by establishing empirical relationships of the bed-load discharge and the suspended-load discharge with the mean flow velocity and the water discharge.