نتایج جستجو برای: gravel bed

تعداد نتایج: 52222  

2003
Yantao Cui Gary Parker James Pizzuto Thomas E. Lisle

[1] Mountain rivers in particular are prone to sediment input in the form of pulses rather than a more continuous supply. These pulses often enter in the form of landslides from adjacent hillslopes or debris flows from steeper tributaries. The activities of humans such as timber harvesting, road building, and urban development can increase the frequency of sediment pulses. The question as to ho...

2008
Jonathan D. Stock Kevin M. Schmidt David M. Miller

Water and debris fl ows exiting confi ned valleys have a tendency to deposit sediment on steep fans. On alluvial fans where water transport of gravel predominates, channel slopes tend to decrease downfan from ~0.10–0.04 to ~0.01 across wide ranges of climate and tectonism. Some have argued that this pattern refl ects grain-size fi ning downfan such that higher threshold slopes are required just...

2014
Simone D. Langhans Klement Tockner

Understanding complex, dynamic, and diverse ecosystems is essential for developing sound management and conservation strategies. Gravel-bed river floodplains are composed of an interlinked mosaic of aquatic and terrestrial habitats hosting a diverse, specialized, and endangered fauna. Therefore, they serve as excellent models to investigate the biodiversity of multiple ecotones and related edge...

2009
Arvind Singh Kurt Fienberg Douglas J. Jerolmack Jeffrey Marr Efi Foufoula-Georgiou

[1] In the paper ‘‘Experimental evidence for statistical scaling and intermittency in sediment transport rates’’ by A. Singh et al. (Journal of Geophysical Research, 114, F01025, doi:10.1029/2007JF000963, 2009), we performed a multiscale analysis of bed load sediment transport series collected in a large-scale experimental flume at the St. Anthony Falls Laboratory at the University of Minnesota...

Journal: :Ground water 2017
Thomas Wöhling Moritz J Gosses Scott R Wilson Peter Davidson

New Zealand's gravel-bed rivers have deposited coarse, highly conductive gravel aquifers that are predominantly fed by river water. Managing their groundwater resources is challenging because the recharge mechanisms in these rivers are poorly understood and recharge rates are difficult to predict, particularly under a more variable future climate. To understand the river-groundwater exchange pr...

2000
Stephen Rice

The size distribution of the sediments in the bed of a stream channel is a significant characteristic of fish habitat. Spawning gravels are sampled during habitat assessments and monitoring programs. Within a given stream, effective, representative sampling requires a clear understanding of the spatial variation of spawning gravel characteristics. This study documents and explains the spatial v...

1993
Sue Hilton Thomas E. Lisle

USDA Forest Service Res. Note PSW-RN-414-WEB. 1993. E xperienced hydrologists and geomorphologists can estimate the relative mobility of a streambed by looking at indicators of bedload transport, such as the freshness of bed-surface material. Another such indicator is the amount of fine sediment in pools. Pools in gravelbed streams commonly contain deposits of fine sediment (mostly sand and gra...

1998
J. H. CHANDLER

This paper presents a procedure for assessing the quality of a digital elevation model (DEM) which has been applied to the output of a normalized cross correlation based stereomatching algorithm. Using semimetric photography of natural gravel river bed surfaces acquired in the field, digital photogrammetry was used to extract DEMs automatically for use in characterizing surface roughness proper...

2015
STEPHANE BERTIN

Field characterization of gravel-bed surface structure is important for studies on flow resistance, sediment transport and in-stream habitats. The following study presents technical developments that make obtaining highresolution digital elevation models (DEMs) from gravel beds in the field more efficient and effective. Using close-range digital photogrammetry (CRDP), only two consumer-grade di...

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