نتایج جستجو برای: dune sand
تعداد نتایج: 29993 فیلتر نتایج به سال:
Vegetation patterns are strongly influenced by sand mobility in desert ecosystems. However, little is known about the spatial patterns of Artemisia ordosica, a dominant shrub in the Mu Us desert of Northwest China, in relation to sand fixation. The aim of this study was to investigate and contrast the effects of sand dune stabilization on the population and spatial distribution of this desert s...
The megathrust earthquake of moment magnitude 9.1 – 9.3 on December 26, 2004 unleashed a massive tsunami which devastated the coastal belts of Sri Lanka as well as several other countries bordering the Indian Ocean. Extensive field observations carried out in Sri Lanka in the aftermath of the tsunami clearly showed that the spatial variation of the degree of destruction along the coastal belt w...
Large dune fields can overrun for instance infrastructures lying in the way of their motion. Unidirectional wind fields and low sand availability give rise to single barchan dunes moving in the direction of wind. They can interact by directly exchanging their sand through collisions. This kind of interaction plays a crucial role in the evolution of barchan dune fields, for instance on the selec...
This study aims to identify favorable oil–gas reservoir facies in the Chishan group of the Wubao fault zone (Gaoyou sag, Subei basin, China) using the methods of outcrops and cores observation, granularity analysis, scanning electron microscope, log data, etc. The results suggest that the Chishan group in the studied area mainly develops desert sedimentary system, and contains five kinds of fac...
Fine-grained materials of Clayey Loess deposits of Gorgan region were mixed with sand dune in the lab with various rations and their shear behavior was measured and evaluated by direct shear test. The result of the study showed that the increase of fine-grained clay in sand dune was directly related to the adhesion force and inversely to the internal friction angle. The increase or reduction in...
Introduction: Eolian dune fields found within Ti-tan's equatorial region between +30° latitude cover approximately 15-17% of the moon's surface [1]. These dominantly linear dunes are similar in form, size, and radar reflectivity to the large dunes of the Namib, Saharan, Saudi Arabian, and Australian deserts [2][3]. Earth analog studies indicate that the presence of linear dunes suggests adequat...
The study of dune morphology represents a valuable tool in the investigation of planetary wind systems--the primary factor controlling the dune shape is the wind directionality. However, our understanding of dune formation is still limited to the simplest situation of unidirectional winds: There is no model that solves the equations of sand transport under the most common situation of seasonall...
In the present work, we use dune modeling in order to investigate the evolution of transverse dunes in the presence of vegetation. The vegetation is allowed to grow up to a maximum height Hmax with a growth rate R that oscillates in time. We find that the presence of the vegetation establishes a maximum height for the transverse dunes. If the transverse dune is larger than this maximum size, th...
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...
In this work, we present measurements of the height profile, wind velocity and sand flux performed on transverse dunes in the dune field known as “Lençóis Maranhenses”, northeastern Brazil. From the measured profile, we selected one dune to measure the air shear stress and the sand flux and compared the results with the theoretical predictions from a dune model in two dimensions recently introd...
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