نتایج جستجو برای: river bed

تعداد نتایج: 131107  

2010
H. Van der Klis

Hydrodynamic river models are applied to design and evaluate measures for purposes such as safety against flooding. The modeling of river processes involves numerous uncertainties, resulting in uncertain model results. Knowledge of the type and magnitude of these uncertainties is crucial for a meaningful interpretation of the model results. The aim of this study is to quantify the uncertainty d...

Journal: :Bulletin of the World Health Organization 2007
Antonio Postigo Andy Haines Maria Neira Ulisses Confalonieri

The photo “Sleeping on the river bed” by Nimai Chandra Ghosh won a special mention in the WHO photo and video contest Images of Health and Disability 2007 Special Theme: Health and Environment. A boy sleeps on a dried-up river bed in India. Experts believe that climate change is increasing the frequency and severity of droughts. N im ai C ha nd ra G ho sh Will increased awareness of the health ...

Journal: :The Science of the total environment 2001
P N Owens D E Walling J Carton A A Meharg J Wright G J Leeks

Samples of suspended, floodplain and channel bed sediment have been used to examine downstream changes in ediment-associated contaminant transport and storage in contrasting rivers in Yorkshire, UK. The concentrations of hosphorus, chromium and selected PCBs associated with sediment in the River Aire and its main tributary, the River Calder, which drain an urbanized and industrialized catchment...

2012
Arvind SINGH Michele GUALA Stefano LANZONI

Quantification of river bedform variability and complexity is important for sediment transport modeling as well as for characterization of river morphology. Alluvial bedforms are shown to exhibit highly nonlinear dynamics across a range of scales, affect local bed roughness, and vary with local hydraulic, hydrologic, and geomorphic properties. This paper examines sediment sorting on the crest a...

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In addition to Erodibility of sediment particles in river increase river sediment load, they are important factors in morphological changes. In the rivers that erodibility is high, trend of morphological changes are intensive that in this case, river is unstable. On the contrary, it will lead stability and low changes of the river. Study area of this research is Saraskanchay that has been locat...

2013
E. EVANS A. C. WILCOX

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...

2005
Michael Burke John M. Buffington

The regulated hydrograph of the Kootenai River between Libby Dam and Kootenay Lake has altered the natural flow regime, resulting in a significant decrease in maximum flows (60% net reduction in median 1-day annual maximum, and 77%-84% net reductions in median monthly flows for the historic peak flow months of May and June, respectively). Other key hydrologic characteristics have also been affe...

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Changes in a river's geomorphologic pattern would be considered in all environmental plannings because this change has special consequences on land ownership properties, the use of cultivable lands on rivers' banks and supply of constructional materials. Sand and gravelmining of the river beds are among factors that lead to changes in river bed patterns. In this research, we investigate geomorp...

2010
Young Ho Shin

The changes in channel geometry downstream of Hapcheon Dam, South Korea, are closely examined. Daily pulses of water from peak hydropower generation and from sudden sluice gate operations affect the 45-km reach of the Hwang River between the Hapcheon Reregulation Dam and the Nakdong River. From 1983 to 2003, the median bed-material size, d50, increased from 1.0 to 5.7 mm, and the bed slope of t...

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