نتایج جستجو برای: bed depth

تعداد نتایج: 208458  

Journal: :آب و خاک 0
سمیه پوربخشیان محمدرضا مجدزاده طباطبائی سید سعید موسوی ندوشنی شهرام منصوری

abstract morphological river models are designed to provide physical insight into the morphological response and to assist river engineers and managers in the design, operation and maintenance of river systems. here deterministic modeling weak for a dynamic and stochastic of nature river environment. specially, these could not predict the exact shape of the river bed, specially e.g. for braided...

A.A Dehghani M.R Pirestani T Esmaeili Tetsuya Sumi

Local scouring around bridge piers is a natural phenomenon caused by the erosive process of flowing stream on alluvial beds. The 3D flow field around bridge piers interacting with the bed materials increases complexity of local scour process. The local scour depth develops in accelerated flows and if it is not predicted correctly, the bottom level of local scour hole will exceed the original le...

شمال نسب, بابک, فتحی مقدم, منوچهر, مسجدی, علیرضا,

Tamarix sricta plant grows in riversides of Karun river. Outer body plant in the flood times causes decrease in water velocity, preventing erosion. One of the factors by which the hydraulic resistance is expressed is the roughness coefficient. Measurement of roughness coefficient of the existing plants in these riversides and floodplains, and surveying their effects on the velocity decrease and...

ژورنال: علوم آب و خاک 2011
علیرضا مسجدی, , مهدی غلامزاده محمودی, ,

Every year river flooding causes serious damage to the bridges at the time needed most. One of the most effective factors causing bridge failure is scouring around the piers in a river bend. One of the methods to decrease scouring around the bridge piers is fitting them with a coller on the piers. The collars protect the river bed against vortex flow in the vicinity of the pier base. An experim...

ژورنال: علوم آب و خاک 2018

In this study, the performance of slot in the spur dike was evaluated as a way to reduce the scouring around the installed flat spur dike in a 180 degree bend and the development of scouring in the slotted spur dike was compared with that of the spur dike with no slot. To evaluate the effect of the slot on the development of scouring around it, a flat spur dike made of Plax Glass was installed ...

The drops are used to control the descents,  stabilize the bed level, and control the upstream water level in sloping channels with less slope than the ground slope. The current study presents a numerical analysis of hydraulic characteristics in the vertical drop using computational fluid dynamics. At first, the laboratory models were used for verification and choosing the best model of turbule...

2001
Tim Lauck Roland Lamberson Thomas E. Lisle

Salmonid embryos depend on the adequate flow of oxygenated water to survive and interstitial passageways to emerge from the gravel bed. Spawning gravels are initially cleaned by the spawning female, but sediment transported during subsequent high-runoff events can nfiltrate the porous substrate. In many gravel-bed channels used for spawning, most of the infiltrating sediment consists of sand an...

Journal: :E3S web of conferences 2021

The objectives of this study are: 1) to capture the existing condition river channel in Sangatta River estuary, including bathymetry bed, and cross-sectional dimensions river, 2) design a stable navigation estuary that allows less maintenance dredging improves navigability during critical when water level is at lowest, 3) test effectiveness cross section term availability navigable depth. This ...

2016
Ulrika Källman Sara Bergstrand Anna-Christina Ek Maria Engström Margareta Lindgren

OBJECTIVES To describe individual BF responses in a nursing home resident population for one-hour periods of bed rest. METHODS BF was measured for one hour over the sacrum in 0° supine position and 30° supine tilt position in 25 individuals aged 65 y or older while lying on a pressure-redistributing mattress. Measurements were made at three tissue depths (1, 2, and 10 mm) using the noninvasiv...

2008
A. J. Roberts D. J. Georgiev D. V. Strunin

Floods, tides and tsunamis are turbulent, yet conventional models are based upon depth averaging inviscid irrotational flow equations. We propose to change the base of such modelling to the Smagorinksi large eddy closure for turbulence in order to appropriately match the underlying fluid dynamics. Our approach allows for large changes in fluid depth to cater for extreme inundations. The key to ...

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