Geological and geotechnical aspects of Saudi Arabia     

T. Al-Refeai  D. Al-Ghamdy 《Geotechnical and Geological Engineering》1994,12(4):253-276

Summary This paper presents a brief review of the geological and geotechnical aspects of the Kingdom of Saudi Arabia. The first part of the paper presents a brief summary of the geological aspects and the soil characteristics in different parts of the country. The second part gives a brief outline of the major geotechnical problems encountered in the regions of the Kingdom along with their geographical locations.  相似文献   

Two types of longitudinal dune fields and possible mechanisms for their development   总被引：1，自引：0，他引：1  

George Tseo 《地球表面变化过程与地形》1993,18(7):627-643

Longitudinal dune fields characterized by nearly uniform interdune spacing are distinguished from longitudinal dune fields characterized by fairly variable interdune spacing and high frequencies of dune coalescence. The empirical and theoretical evidence indicating that the former may be due to helical air currents aligned with the dunes is reviewed. Hypotheses arguing that the latter may arise indirectly from horizontal pressure gradients or bidirectional wind regimes are discussed. Evenly spaced linear sand banks aligned with tidal currents may be shown mathematically to result from energy optimalization within two-dimensional, sand-transporting flow regimes, and a similar simple or non-rotational flow model is considered for the problem of desert longitudinal dunes. An initial complex or rotational flow analysis is undertaken to discern the likely significance of roll vortices in desert sediment transport. An ‘evolutionary timescale’ is estimated for the formation of desert longitudinal dune fields. A simple analysis is performed for the effect of regional sand mass change on longitudinal dune field ordering. Recommendations are made for future empirical and theoretical research.  相似文献   

A second look at western Sinai seif dunes and their lateral migration   总被引：1，自引：0，他引：1  

David M. Rubin  Haim Tsoar  Dan G. Blumberg 《Geomorphology》2008,93(3-4):335-342

Tsoar et al. [Tsoar, H., Blumberg, D.G., Stoler, Y., 2004. Elongation and migration of sand dunes. Geomorphology 57, 293–302.] reported that seif dunes in the western Sinai Desert did not migrate laterally between 1973 and 1999. If the planform sinuosities of the dunes are removed by filtering, spatial averaging, or linear regression, however, it is evident that the dunes did, in fact, migrate laterally roughly 13 m during this 26-year period. The measured migration distance is 1–2 orders of magnitude greater than the rms co-registration error Tsoar et al. determined for the first and last air photos that were used to map the dunes. The western Sinai dunes provide another example demonstrating that linear dunes can migrate laterally, and they illustrate some of the difficulties in documenting systematic lateral motion.Lateral migration of a dune can be important geologically or geomorphologically, even where migration is too slow to detect from repeated topographic surveys. This article explains the wind conditions for the lateral migration of seif dunes in western Sinai and the possible wind occurrences that would not lead to such a migration.  相似文献   

On the origin and age of the Great Sand Dunes, Colorado     

Richard F. Madole  Joe H. Romig  John N. Aleinikoff  D. Paco VanSistine  Ezra Y. Yacob 《Geomorphology》2008,99(1-4):99-119

  相似文献   

艾比湖流域抛物线沙丘表层沉积物粒度特征     

马倩  武胜利  刘永泉  贾春荣 《中国沙漠》2014,34(3):650-657

对艾比湖流域抛物线沙丘表层沉积物样品的实验分析结果表明：沙丘表层沉积物粒径分布在0.4~2116.5 μm。沙丘表层沉积物主要成分为沙,且含有一定量的细砾和黏土成分;平均粒径从两翼间地至丘顶逐渐变粗,丘顶至背风坡脚逐渐变细;沉积物分选性整体较差,平均粒径愈小,分选性愈好;粒径频率曲线为正偏、基本对称、负偏和极负偏混合存在。沙丘表层沉积物的平均粒径与分选系数存在不显著的负相关性,与峰态呈现显著负相关,分选系数与峰态呈现显著正相关性。沙丘不同地貌部位沉积物的粒级、平均粒径、分选系数呈现出有规律的变化,系风沙流、沙丘形态、植被和沉积物综合作用的结果。艾比湖流流域内抛物线沙丘的物质来源为两个或两个以上的沉积物混合形成的多源供应物。  相似文献   

库姆塔格沙漠羽毛状沙丘剖面特征     

王永胜  杨文斌  李永华  左合君  王学全  丁峰  刘宝河  董威龙  梁海荣 《中国沙漠》2014,34(2):318-324

在库姆塔格沙漠羽毛状沙丘分布区选取典型地段作为观测区,运用全站仪测量了观测区羽毛状沙丘地形特征。结果如下：（1） 构成羽毛状沙丘羽轴的沙垄由首尾相连的变形的新月形沙丘构成,其走向为N55°E;新月形沙丘的平均高度为17.65 m,西北翼角的平均长度为72 m,均长于东南翼角。（2） 沙垄的纵断面（SW→NE）表现出明显的波动性,波长在50～100 m之间,波高在10～25 m之间。（3） 沙垄的平均宽度为127.69 m,平均坡度为12.59°;西北坡平均坡长为71.74 m,平均坡度为11.65°,东南坡平均坡长为59.05 m,平均坡度为13.52°。（4） 羽毛状沙丘的“羽枝”部分是由地形平缓的穹状大沙波首尾相连构成,并未像遥感影像一样呈现出明暗相间的羽毛状图案。大沙波的平均宽度为641.34 m,其纵断面相对平缓,2个波峰之间的距离在400 m左右,波峰高度为1～3 m,平均坡长为322.37 m,平均坡度为1.28°,仅为沙垄的10%。  相似文献   

Delineating stratigraphic breaks at the bases of postglacial eolian dunes in central Alberta,Canada using a portable OSL reader     

Kennedy Munyikwa  Selena Brown  Zehra Kitabwalla 《地球表面变化过程与地形》2012,37(15):1603-1614

Temporal constraints for the Late Pleistocene deposition of eolian dunes that occur in central and northern Alberta, Canada can be provided by dating sediments from the dune bases using luminescence techniques. In places, however, the postglacial dunes overlie glaciofluvial sands that resemble the eolian deposits in texture such that demarcating the bases of the dunes is often problematic. In this study we address the problem by employing a portable optically stimulated luminescence (OSL) reader to construct luminescence profiles that depict luminescence signal variation with depth. With the portable OSL reader, measurement can be performed on bulk sediments, negating the need for laborious separation procedures to isolate pure mineral fractions, as is required in regular luminescence dating. Measurements can also be carried out in the field, permitting quicker decision making during sample collection. Results from this study, presented as depth variations of feldspar derived infrared stimulated luminescence (IRSL) signals and predominantly quartz‐generated post‐IR blue OSL signals, show that luminescence profiling enables one to distinguish between eolian deposits that make up the dunes from the underlying non‐eolian sands. The identification of such cryptostratigraphic interfaces is made possible by differences in the dosimetric histories of the sediments. The delineation of the dune bases allows targeted sampling that yields best luminescence age approximations for the initiation of postglacial eolian deposition in the region. Luminescence profiling of eolian sequences would also, in theory, permit the identification of depositional breaks of extended duration. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

库姆塔格沙漠典型线形沙丘粒度特征   总被引：5，自引：2，他引：3  

苏志珠  梁爱民  马义娟  吴波  庞营军  李继彦  高君亮 《中国沙漠》2016,36(4):877-884

对库姆塔格沙漠不同区域典型线形沙丘不同地貌部位的表层沉积物进行了粒度分析。结果表明：线形沙丘沙物质组成的优势粒级为中沙、细沙和极细沙,所占比重分别为28.85%、30.92%和25.98%。根据沙丘剖面形态和粒度特征,该沙漠的线形沙丘可分为两大类,第一类剖面形态不对称,沙物质由沙丘两翼底部向脊部逐渐细化、分选变好,分布于沙漠的东北部、中部、南部和西部;第二类剖面形态较为对称,沙物质在两翼中部最细,脊部最粗,坡脚次之,分选性无明显变化规律,分布于沙漠的东部。对这两类线形沙丘粒度特征的形成原因做了探讨,初步认为第一类是沙物质经风选的结果,而第二类则是风选、物源风化等综合影响的结果。  相似文献   

中国沙漠(地)深层渗漏量及动态特征   总被引：1，自引：1，他引：0  

冯伟  杨文斌  唐进年  李卫  党宏忠  梁海荣  张志山 《中国沙漠》2015,35(5):1362-1370

土壤水分深层渗漏是沙区水循环的重要环节,深层渗漏的定量测定对沙区水资源评估及水量平衡研究具有重要意义。本文采用YWB-01型土壤深层水量渗漏测试记录仪对中国毛乌素沙地等六大沙漠(地)降雨入渗到深层土壤的渗漏水量进行实时动态监测。结果表明:流动沙丘降雨渗漏补给量存在明显的时空差异,与降雨时空变化特征具有相对一致性,降雨格局是影响深层渗漏过程的主要因素,随降雨增大渗漏补给量增加,半干旱区降雨量与渗漏量显著正相关(p<0.05),干旱区相关性不显著(p>0.05);观测期内正镶白旗、伊金霍洛旗、阜康流动沙丘土壤200 cm以下渗漏量为48.5、146.8、1.0 mm,分别占同期降雨的21.4%、33.3%、1.3%;乌审旗、磴口150 cm以下渗漏量为1009.6、52.6mm,分别占同期降雨的55.7%、12.7%。不同气候区固定沙丘渗漏量基本没有差异,降雨格局不是影响水分深层渗漏的主导因素,而植被覆盖的影响占主要作用,且沙丘植被盖度>45%时深层渗漏量不超过同期降雨的2.0%。中国沙区深层土壤水分补给主要来自于强降雨或高频次小降雨事件,特别是干旱区降水少、频次低,其深层土壤水分补给更加依赖于强降水。  相似文献   

Research Progress of Coastal Dunes Response to Storm   总被引：1，自引：0，他引：1  

Yang Lin  Dong Yuxiang  Du Jianhui 《地球科学进展》2017,32(7):716-722

The major areas of world coastal dunes have been frequently attacked by storms. The storm, as a high energy influential factor for the formation and evolution of coastal dunes, is also one of the important research contents on the surf zone-beach-dune interaction. The research progress are reviewed from the following aspects: Coastal dune morphological response to storms, coastal dune sediments response to storms, mechanisms of coastal dunes in response to storms, and the research methods and techniques used in the research on coastal dunes to storms. Finally, open questions and future developments were suggested.  相似文献