نتایج جستجو برای: meander and deeping rivers beds

تعداد نتایج: 16832169  

Journal: :پژوهش های جغرافیای طبیعی 0
مریم بیاتی خطیبی فریبا کرمی داود مختاری

in semi arid area geomorphological impacts of dams are very major. dams, as man- made structures, have major impacts on river hydrology, primarly through in the timing, magnitude, and frequency of low and high flows, ultimately producing a hydrologic regime differing significantly from the pre-impoundment natural flow regime. despite the profiles of dams on river regulation for water resources ...

Journal: :Computers & Geosciences 2006
Jorge D. Abad Marcelo H. García

RVR Meander was developed as a toolbox for modeling restoration and naturalization processes in rivers. This model includes Windows-based and Geographical Information System-based programs for analyzing and modeling planform migration of streams. In the past, several rivers have been channelized causing environmental and ecological problems. Restoration techniques evolve as natural solutions to...

2009
V. R. Baker

Venusian lava channels have meander dimensions that relate to their mode of formation. Their meander properties generally follow terrestrial river trends of wavelength (L) to width (W) ratios, suggesting an equilibrium adjustment of channel form. Slightly higher L/W for many Venusian channels in comparison to terrestrial rivers may relate to nonaqueous flow processes. The unusually low L/W valu...

2013
Nathan D. Jackson Christopher C. Austin

Despite considerable attention, the long-term impact of rivers on species diversification remains uncertain. Meander loop cutoff (MLC) is one river phenomenon that may compromise a river's diversifying effects by passively transferring organisms from one side of the river to the other. However, the ability of MLC to promote gene flow across rivers has not been demonstrated empirically. Here, we...

2007
V. J. Bray D. B. J. Bussey R. C. Ghail A. P. Jones K. T. Pickering

[1] The similar meander geometries of Venusian canali and terrestrial rivers imply that the in-channel flow regimes may be comparable. This work details meander geometry measurements from ten lowland canali and compares the extensive data set produced to a variety of solar system channels. The meander properties of Venusian canali do not closely match any channel so far observed on the terrestr...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تربیت مدرس - دانشکده علوم انسانی 1389

rivers and runoff have always been of interest to human beings. in order to make use of the proper water resources, human societies, industrial and agricultural centers, etc. have usually been established near rivers. as the time goes on, these societies developed, and therefore water resources were extracted more and more. consequently, conditions of water quality of the rivers experienced rap...

Journal: :تحقیقات جغرافیایی 0
مریم بیاتی خطیبی دانشگاه تبریز

meanders are among the important characteristics of some rivers that flow in semi-arid regions. swift displacement along the river's flow, change in the location of the central ridge and bank erosion leateral erosion are resulted from making meander in the river's flow. meanders in river courses on north east slopes of sahand (located in 46ëš 43ì to 47ëš 15ì e and from 36ëš 05ììì...

2013
Leif Karlstrom Parmesh Gajjar Michael Manga

[1] Meandering streams on the surface of glaciers are similar in planform geometry to meanders in alluvial and bedrock rivers, despite fundamental differences in the mechanisms and timescales of incision. We develop depth-averaged conservation equations for flow in such supraglacial channels with erodible boundaries and solve the linear stability problem for harmonic perturbations to an initial...

Journal: :تحقیقات آب و خاک ایران 0
سید محمد علی زمردیان دانشیار دانشگاه شیراز مجتبی عقلی دانشجوی کارشناسی ارشد، دانشگاه شیراز

a large number of authors have studied to find out how to control scouring around a pier along direct stream. the objective of this research is then to study a scour pattern around such piers on curves rivers due to the fact that there may be a difference between a flow pattern on a direct line and the meander. thus, this study tries to check whether the use of cable and collar alone and in a c...

2017
M. Azpiroz-Zabala E. J. Sumner M. A. Clare P. J. Talling D. R. Parsons C. Cooper

Meandering channels formed by geophysical flows (e.g., rivers and seafloor turbidity currents) include the most extensive sediment transport systems on Earth. Previous measurements from rivers show how helical flow at meander bends plays a key role in sediment transport and deposition. Turbidity currents differ from rivers in both density and velocity profiles. These differences, and the lack o...

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