نتایج جستجو برای: fluvial

تعداد نتایج: 4448  

2014
Arman Haddadchi Darren S. Ryder Olivier Evrard Jon Olley

Suspended sediments in fluvial systems originate from a myriad of diffuse and point sources, with the relative contribution from each source varying over time and space. The process of sediment fingerprinting focuses on developing methods that enable discrete sediment sources to be identified from a composite sample of suspended material. This review identifies existing methodological steps for...

2012
Gregory J. Retallack

Despite evidence that weathering plays a role in forming intertidal, estuarine, and fluvial rock platforms, many publications uncritically refer to “wave-cut” or “stream-cut” rock platforms. The alternative explanations of chemical weathering and physical water erosion of rock platforms have been debated since 1839. Our new approach to this long-standing problem introduces data from fluvial as ...

2009
Mikaël Attal Jérôme Lavé

[1] In actively eroding landscapes, fluvial abrasion modifies the characteristics of the sediment carried by rivers and consequently has a direct impact on the ability of mountain rivers to erode their bedrock and on the characteristics and volume of the sediment exported from upland catchments. In this experimental study, we use a novel flume replicating hydrodynamic conditions prevailing in m...

Varied flows such as flooding resulting from dam break can happen due to earthquakes, seepage, bombing, overtopping, mistake in design and project performance as well as causing financial damages and human losses. Unsteady flow during flooding events has a high impact on flow field pattern, sediment motion, ecology and also, distribution of contamination in the river. In this study, the impact ...

2012
W. Wyatt Oswald Daniel G. Gavin Patricia M. Anderson Linda B. Brubaker Feng Sheng Hu

Analyses of lithology, organic-matter content, magnetic susceptibility, and pollen in a sediment core from Okpilak Lake, located in the northeastern Brooks Range, provide new insights into the history of climate, landscape processes, and vegetation in northern Alaska since 14,500 cal year BP. The late-glacial interval ([11,600 cal year BP) featured sparse vegetation cover and the erosion of min...

Journal: :Archives of environmental contamination and toxicology 2014
David D Edwards Paul A Moore

In fluvial systems, organismic exposure to nonpoint source pollutants will fluctuate in frequency (exposure events), intensity (concentration), and duration. The reliance on lethal concentrations and static exposure in many laboratory studies does not adequately represent nor address exposure to in situ chemical plumes of fluvial habitats. To adequately address field exposure in a laboratory se...

Journal: :تحقیقات مهندسی کشاورزی 0
امیر صمدی استادیار گروه مهندسی آب دانشکده فنی و مهندسی دانشگاه بین المللی امام خمینی (ره) محمدهادی داودی دانشیار بازنشسته پژوهشکده حفاظت خاک و آبخیزداری ابراهیم امیری تکلدانی دانشیار بازنشسته گروه مهندسی آبیاری و آبادانی دانشکده مهندسی و فناوری کشاورزی دانشگاه تهران حسن رحیمی استاد بازنشسته گروه مهندسی آبیاری و آبادانی دانشکده مهندسی و فناوری کشاورزی دانشگاه تهران

because it is not possible to recognize the mechanism of cantilever failure in field studies, this type of common failure in riverbanks is investigated in the laboratory. for this purpose, two samples of susceptible soil that forms an overhanging block in riverbanks are used for physical model tests to determine their physical, chemical and mechanical characteristics. soil blocks of different d...

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