نتایج جستجو برای: sediment threshold

تعداد نتایج: 158501  

Journal: :Environmental research 2007
David H Schoellhamer Thomas E Mumley Jon E Leatherbarrow

Water-quality managers desire information on the temporal and spatial variability of contaminant concentrations and the magnitudes of watershed and bed-sediment loads in San Francisco Bay. To help provide this information, the Regional Monitoring Program for Trace Substances in the San Francisco Estuary (RMP) takes advantage of the association of many contaminants with sediment particles by con...

2010
Dallas L. Peck

Data were collected at two small, semiarid basins in Wyoming to determine the relation between rainfall, runoff, and sediment production. The basins were Dugout Creek tributary and Saint Marys Ditch tributary. Sufficient rainfall and runoff data were collected at Dugout Creek tributary to determine the source of sediment and the dominant sediment-production processes. Because runoff from only o...

2017
Michael Müller Giovanni De Cesare Anton J. Schleiss

In laboratory experiments, the influence of inflow and outflow sequences on the behavior of fine sediment was investigated. The experimental set-up consisted of two interconnected rectangular basins, between which water was moved back and forth. Suspended sediment concentration in the main basin as well as the sediment exchange rates were derived from turbidity measurements.The suspended sedime...

2009
Xiaobo Chao Yafei Jia F. Douglas Shields Sam S. Y. Wang Charles M. Cooper

Three major sediment-associated processes were presented to describe the effects of sediment on the water quality processes, including the effect of sediment on the light intensity for the growth of phytoplankton (PHYTO), the adsorption–desorption of nutrients by sediment and the release of nutrients from the bed sediment layer. A formula was generated from field measurements to calculate the l...

Journal: :Applied and environmental microbiology 1982
P LaLiberte D J Grimes

The survival of Escherichia coli in bottom sediment (Lake Onalaska, navigation pool no. 7, Mississippi River) was studied by using in situ dialysis culture of sterile (autoclaved) and unsterile sediment samples. Bags made from dialysis tubing were filled with either course sand sediment (28.8% fine) or organic, silty clay sediment (77.2% fine) and placed at the sediment-water interface. Bags re...

This study is aimed at estimating suspended sediment load in watersheds using hydro-climatic factors with the intent to determine spatial and temporal variations of sediment yield in Qarah Su drainage basin, Ardebil Province. For this study, data from seven rain gauge and hydrometric stations during a 22-year period were used. The research was based on statistical regression analysis between va...

2014
Alice H. Nelson Paul R. Bierman Jeremy D. Shakun Dylan H. Rood

We use the concentration of in situ Be in quartz isolated from fluvial and morainal sand to trace sediment sources and to determine the relative contribution of glacerized and deglaciated terrain to Greenland’s sediment budget. We sampled along the western, eastern, and southern margins of the Greenland Ice Sheet, and collected sediment sourced from glacerized (n=19) and non-glacerized terrain ...

2005
Mitchell Lyle Neil Mitchell Nicklas Pisias Alan Mix Jose Ignacio Martinez Adina Paytan

[1] The paleoceanographic recording fidelity of pelagic sediments is limited by chemical diagenesis and physical mixing (bioturbation and horizontal sediment transport). Diagenesis and bioturbation are relatively well-studied, but the effects of physical sedimentation have been largely ignored. Modeling U series isotopes (e.g., Th) can potentially quantify horizontal sediment movement, but mode...

Journal: :Environmental Modelling and Software 2014
Gianbattista Bussi Félix Francés Juan José Montoya Pierre Y. Julien

The importance of initial sediment conditions on model calibration and validation is analysed. A sediment model was calibrated and validated under three different initial sediment conditions: (0) no sediment availability, (1) calibration of the initial sediment condition and (2) using a warm-up simulation. The model results were assessed in terms of the graphic of fine sediment transport, or se...

2015
M.C.J.L. Jeuken

a r t i c l e i n f o The impact of dredging and dumping on the morphologic stability of the tidal channels is investigated using morphologic field observations for the Westerschelde estuary dating back to 1955. The results are used to verify the theoretical concept presented by Wang and Winterwerp (2001). This concept states that a critical threshold for the amount of sediment dumping exists a...

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