نتایج جستجو برای: permanent gullies

تعداد نتایج: 62766  

Journal: :ecopersia 2014
farhad nourmohammadi ali haghizadeh

understanding the development of gully volumes requires the empirical relations between gully volume (v) and length (l) to be established in the field. so far, such v–l relations have been proposed for a limited number of gullies/environments and were especially developed for ephemeral gullies.in this study, v–l relations were established for ephemeral gullies in southern ilam. in order to take...

2009
T. Kneissl D. Reiss S. van Gasselt G. Neukum

Introduction: Gullies show morphologic features that indicate the presence of a flowing liquid during their forming process [1]. However, the current climate in the northern hemisphere of Mars does not allow the existence of substantial amounts of liquid water for a long time. Therefore, the exploration of particular young landforms, such as gullies is a valuable tool for understanding the most...

2006
Nina L. Lanza Martha S. Gilmore

Introduction: Martian gullies were first identified by Malin and Edgett [1]. Previous work [2] has examined the characteristics of gullies in the southern hemisphere in detail. Less detailed work has been done for the northern hemisphere [3,4]. Gullies are found predominantly in the midlatitudes of both hemispheres between 30°-50° [1,2], which implies a thermal control on their formation. Sever...

2013
Aderemi Adediji Matthew Olomolatan Ibitoye

This study examined the development of urban gullies in a part of Southwestern Nigeria. This was done with a view to determine the volume and amount of sediment loss from the 1 and 2 order gullies in a cascade system. Twenty (20) towns were randomly selected from where thirty (30) gully systems comprising forty (40) 1 order and five (5) 2 order gullies were measured with Tape and Total Station ...

2009
N. Mangold

Recent gullies are erosional landforms developed on hillslopes in recent Martian time (less than 10 My). The nature of the fluid that created the erosion was initially considered as debris flows, but this is still under discussion. Indeed, hypotheses invoking only dry granular slides explain many characteristics of the gullies channels, their size, length, presence of levees and terminal deposi...

Journal: :ISPRS Int. J. Geo-Information 2017
Xin Yang Wen Dai Guoan Tang Min Li

Monitoring ephemeral gullies facilitates water planning and soil conservation. Artificial interpretation based on high spatial resolution images is the main method for monitoring ephemeral gullies in large areas; however, this method is time consuming. In this study, a semiautomatic method for extracting ephemeral gullies in loess hilly areas based on directional edge detection is proposed. Fir...

2009
S. D. Hart V. C. Gulick

Introduction: Since the discovery of gullies on some crater slopes and valley walls [1], there have been several hypotheses put forth concerning their origin and formation [2-10]. This study focuses on gullies that are located on the central peak of Lyot crater located in the Northern Plains of Mars (50.4N, 29.3E). The gullies source between 150m and 750m below the top of the central peak. A pr...

2012
N. Mangold V. Ansan

Gullies on Mars are km-scale landforms that resemble small fluvial features on Earth. Their discovery [1] challenged the paradigm that over the last ∼2 Ga, Mars has been a dry, frozen desert. The gullies are found commonly in the mid-latitudes, have a pole-facing preference [e.g., 2] and are found many kinds of steep slope (valley wall, dunes, etc.). We have chosen to concentrate on gullies fou...

2009
J. S. Levy D. R. Marchant J. L. Dickson

a r t i c l e i n f o a b s t r a c t We describe the morphology and spatial relationships between composite-wedge polygons and Mars-like gullies (consisting of alcoves, channels, and fans) in the hyper-arid Antarctic Dry Valleys (ADV), as a basis for understanding possible origins for martian gullies that also occur in association with polygonally patterned ground. Gullies in the ADV arise in ...

2010
Ryan L. Perroy Bodo Bookhagen Gregory P. Asner Oliver A. Chadwick

a r t i c l e i n f o Gully erosion removes comparatively large volumes of soil from small areas. It is often difficult to quantify the loss of soil because the footprint of individual gullies is too small to be captured by most generally available digital elevation models (DEMs), such as the USGS National Elevation Dataset. Airborne LiDAR (Light Detection and Ranging) has the potential to prov...

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