نتایج جستجو برای: coarse bed rivers
تعداد نتایج: 97968 فیلتر نتایج به سال:
Abstract The period 1965–2000 saw a sustained increase in research and publications on fluvial processes landforms. trend towards generalization and/or mechanistic understanding, rather than site-specific history, continued. Research was multidisciplinary, with important contributions from hydraulic engineers, geologists physical geographers experimental theoretical approaches as well geomorpho...
The relation between the equivalent roughness and different grain size percentiles of the sediment in gravel-bed rivers was determined under the hypothesis that the vertical distribution of the flow velocity follows a logarithmic law. A set of 954 data points was selected from rivers with gravel size sediment or larger, with a non-sinuous alignment and free of vegetation or obstacles. According...
Pulses of fine sediment in gravel-bedded rivers can cause extensive fine sediment infiltration (FSI) into void spaces in coarse bed material, potentially altering river morphodynamics and aquatic ecosystems. Previous work suggests a conceptual model of FSI whereby FSI occurs to a limited depth as a function of the relative grain size of bed sediment compared with infiltrating sediment and is in...
River topography is famously fractal, and the fractality of the sediment bed surface can produce scaling in solute residence time distributions. Empirical evidence showing the relationship between fractal bed topography and scaling of hyporheic travel times is still lacking. We performed experiments to make highresolution observations of streambed topography and solute transport over naturally ...
Median grain sizes on riverbeds range from boulders in uplands to silt in lowlands; however, rivers with ~1–5mm diameter bed sediment are rare. This grain size gap also marks an abrupt transition between graveland sand-bedded reaches that is unlike any other part of the fluvial network. Abrupt gravel-sand transitions have been attributed to rapid breakdown or rapid transport of fine gravel, or ...
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...
Using hydraulic geometry (HG) theory, we investigated three rivers typical of the Ecuadorian mountainous region with longitudinal slopes ranging from 0.8% to 10% and coarse bed material d50 3 54 mm values d90 up 908 mm. Extensive field measurements were performed characterize geometric properties at 33 sites. these data, at-a-station HG relationships obtained for top width, average flow depth, ...
www.frontiersinecology.org © The Ecological Society of America R ecosystems are some of the most diverse on Earth and provide important services (Palmer and Richardson 2009; Strayer and Dudgeon 2010). Understanding how they function is critical to sustainable management but challenging given their complex spatial and temporal structure and multi-scale processes. Riverine systems comprise hydrol...
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