نتایج جستجو برای: sediment

تعداد نتایج: 36882  

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...

2007
Gerald G. Marten

The biomass of sediment organisms can be measured by a.llowing carbon tracer to distribute itself through sediment cores. Application of this method to sediment from Marion lake, British Columbia, indicated that most of the sediment microorganisms were concentrated in the top 2 cm of sediment, where the total biomass of microorganisms was estimated to be 183IJ.g C/cm2• The radiotracer estimate ...

2004
D. J. DeMaster

B the concentration of “reactive” biogenic silica per volume of sediment (mol cm) C the pore-water silicate concentration (mol cm) Cs the pore-water asymptotic silicate value observed at depth in the sediment column (mol cm) DB sediment bioturbation coefficient (cm yr) Ds the molecular diffusion coefficient for silicate in the seabed corrected for tortuosity effects (cm of sediment y) k the dis...

Several types of sediment transport equations have been developed for estimation of the river sediment materials during the past decades. The estimated sediment from these equations is very different, especially when they applied for a specific river. Therefore, choice of an equation for estimation of the river sediment load is not an easy task. In this study 10 important sediment transport equ...

2006
M. H. Nichols

Small watershed sediment yield data were evaluated for eight small watersheds ranging from 35.2 to 159.5 ha within the United States Department of Agriculture – Agricultural Research Service Walnut Gulch Experimental Watershed (WGEW) in southeastern Arizona, USA. Stock pond sediment accumulation measurements covering time periods from 30 to 47 years were combined with water level records and es...

Journal: :نشریه علمی - پژوهشی هیدرولوژی کاربردی 0
omolbani mohammadrezapour mohammad javadzeynali

by far, different models for determining the relationship between the flow rate  and amount of precipitation have been developed. many models are based on regression models with limited assumptions. one of the most common methods for estimating  sediment of rivers is sediment rating curve. for better estimation of the amount of sediment based of sediment curve  rating equation, it is possible t...

2012
Huiming ZHAO Hongwei FANG Hajime NAKAGAWA Hao ZHANG

In aquatic environment, microorganisms such as bacteria and microalgae usually secrete a matrix of mucilaginous extracellular polymeric substances (EPS) to form a “microbial biofilm” when they are associated with solid surfaces (e.g., sediment particles, plant surfaces). Biofilms and the associated mucilaginous secretions form a cohesive matrix surrounding sediment particles, modifying the sedi...

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