نتایج جستجو برای: sand dunes

تعداد نتایج: 29226  

Journal: :The Geographical Journal 1897

2009
James R. Zimbelman Irwin Steven H. Williams Fred Bunch Andrew Valdez Scott Stevens

The rate of movement for 3and 10-cm-high granule ripples was documented in September of 2006 at Great Sand Dunes National Park and Preserve during a particularly strong wind event. Impact creep induced by saltating sand caused 24 granules min 1 to cross each cm of crest length during wind that averaged 9 m s 1 (at a height well above 1 m), which is substantially larger than the threshold for sa...

2007
Galen B. Rathbun Carolyn D. Rathbun

The Namib Desert golden mole (Eremitalpa granti namibensis) is morphologically, physiologically and behaviourally specialized for living in the harsh loose-sand desert. Ecological studies have relied on visually tracking animals on the surface of sand dunes. A radio tag would allow individuals to be more reliably located, even while under the sand. We developed a radio attachment and gathered p...

Journal: :desert 2006
m. r. rajabi f. rohani m. r. ekhtessassi n. ghazanfarpoor

the majority of iran’s area is covered by arid and semiarid climates. in these areas, wind causes more erosion compared to water. therefore, determination of wind characteristics especially its velocity is very important. one of the simplest methods that can supply researchers with the origin of wind erosion in the shortest time is synthesizing sand rose model and interpretation of aerial photo...

In Sistan plain, conditions for wind erosion and, consequently, sand spreads are provided. Due to the settlements in the wind erosion centers of this area, the necessity of determining the origin of sands, the analysis of the hazards caused by the displacement of sand dunes and factors creating these hazards are the goals of this study. It is a descriptive-analytical study based on both field a...

2010
Marco C. M. de M. Luna Eric J. R. Parteli Orencio Durán Hans J. Herrmann

Vegetation greatly affects the formation and dynamics of dune fields in coastal areas. In the present work, we use dune modelling in order to investigate the genesis and early development stages of costal dune fields in the presence of vegetation. The model, which consists of a set of coupled equations for the turbulent wind field over the landscape, the saltation flux and the growth of vegetat...

2005
David M. Rosenthal Fulco Ludwig Lisa A. Donovan

In arid ecosystems, variation in precipitation causes broad-scale spatial heterogeneity in soil moisture, but differences in soil texture, development, and plant cover can also create substantial local soil moisture heterogeneity. The boundary between inland desert sand dunes and adjacent desert habitats exhibits abrupt changes in soil and vegetation characteristics that may be associated with ...

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