نتایج جستجو برای: Sediment Threshold

تعداد نتایج: 158501  

Journal: :Applied Mathematical Modelling 1999

Journal: :آب و خاک 0
سلیمان پور سلیمان پور صوفی صوفی احمدی احمدی

abstract gully erosion is a kind of water erosion that has high priority in fars province due to sediment production and enormous damages to land, roads and infrastructures. in this study, 15 gullies were selected and their morphometric characteristics, such as catchment area, soil, cover vegetation and climate were measured. in order to determine influential factors on the sediment production ...

2014
Ate Poortinga Joep G.S. Keijsers Jerry Maroulis Saskia M. Visser

Aeolian sediment traps are widely used to estimate the total volume of wind-driven sediment transport, but also to study the vertical mass distribution of a saltating sand cloud. The reliability of sediment flux estimations from such measurements are dependent upon the specific configuration of the measurement compartments and the analysis approach used. In this study, we analyse the uncertaint...

2014
Joel Sholtes Kevin Werbylo Brian Bledsoe

Theoretical approaches to magnitude-frequency analysis (MFA) of sediment transport in channels couple continuous flow probability density functions (PDFs) with power law flow-sediment transport relations (rating curves) to produce closed-form equations relating MFA metrics such as the effective discharge, Qeff, and fraction of sediment transported by discharges greater than Qeff, f1, to statist...

The results of an experimental investigation of kerbside bridge deck drainage units are presented. The conveyance capacity, resistance coefficients and sediment transporting efficiencies of different types of drainage unit used in shallow bridge drainage decks are examined over a range of bed gradients likely to be encountered in practice. The use of a V-shaped cross section is shown to be part...

2004
GREGORY E. TUCKER

Long-term average rates of channel erosion and sediment transport depend on the frequency–magnitude characteristics of flood flows that exceed an erosion threshold. Using a Poisson model for rainfall and runoff, analytical solutions are developed for average rates of stream incision and sediment transport in the presence of such a threshold. Solutions are derived and numerically tested for thre...

2016
Vahid Noroozi Karbasdehi Sina Dobaradaran Iraj Nabipour Hossein Arfaeinia Roghayeh Mirahmadi Mozhgan Keshtkar

In this data article, by using inductively coupled plasma optical spectrometry (ICP-OES), we aimed to (1) determine the concentration levels of As, Ag, Sr, Sn, Sb, and Mo in the sediments and the shells of Trachycardium lacunosum simultaneously in two separated areas (unpolluted and polluted areas) (2) comparison between the metal contents of sediments in the unpolluted and polluted areas as we...

Journal: :Marine pollution bulletin 2004
Thomas P O'Connor

While it is being used as such, the sediment quality guideline ERL (effects range low) is not a threshold of any chemical concentration in sediment at which the probability of toxicity shows an abrupt increase. Similarly, while it has been done, there is no basis for assuming that multiple concentrations above an ERL increase the probability of toxicity.

Journal: :Physical review. E, Statistical, nonlinear, and soft matter physics 2013
G Seizilles O Devauchelle E Lajeunesse F Métivier

A viscous fluid flowing over plastic grains spontaneously generates single-thread channels. With time, these laminar analogues of alluvial rivers reach a reproducible steady state, showing a well-defined width and cross section. In the absence of sediment transport, their shape conforms with the threshold hypothesis which states that, at equilibrium, the combined effects of gravity and flow-ind...

2004
Philip W. Gassman Silvia Secchi

The size, scale, and number of subwatersheds can affect a watershed modeling process and subsequent results. The objective of this study was to determine the appropriate level of subwatershed division for simulating flow, sediment, and nutrients over 30 years for four Iowa watersheds ranging in size from 2,000 to 18,000 km2 with the Soil and Water Assessment Tool (SWAT) model. The results of th...

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