库姆塔格沙漠综合科学考察成果初报   总被引：17，自引：9，他引：8  

俄有浩  苏志珠  王继和  翟新伟  刘虎俊  唐进年  丁峰  张锦春  廖空太  郑庆钟 《中国沙漠》2006,26(5):693-697

库姆塔格沙漠地处塔里木盆地罗布泊地区南缘,南以阿尔金山为界,北抵阿奇克堑谷地,向东可延伸至甘肃省境内,总面积约2.29×104 km2,是我国第六大沙漠。考察发现,库姆塔格沙漠气候极干旱,地表植被稀疏,野生动物极少,沙丘流动性大,沙丘类型多样,在其东北部分布着世界上独一无二的羽毛状沙丘。库姆塔格沙漠沙丘下伏地形复杂,沙漠腹地分布出露连续的地层剖面,其蕴藏着反映沙漠形成演化、气候变化与古疏勒河变迁的大量环境信息。开展库姆塔格沙漠综合科学考察,对揭示库姆塔格沙漠的形成与演化、古疏勒河变迁及其与罗布泊退缩的关系、以及西北干旱区气候与环境对青藏高原隆升和全球变化的响应具有重要的科学意义。同时,开展库姆塔格沙漠风沙活动规律、风沙危害的研究以及野生动植物的分布、生态习性等方面的科学考察,对保护世界级的敦煌自然与文化遗产、极干旱地区荒漠生态系统的生物多样性都具有重大现实意义。  相似文献   

Aeolian construction and alluvial dismantling of a fault‐bounded intracontinental aeolian dune field (Teruel Basin,Spain); a continental perspective on Late Pliocene climate change and variability     

JUAN PEDRO RODRÍGUEZ‐LÓPEZ  CARLOS L. LIESA  JAN VAN DAM  PALOMA LAFUENTE  LUIS ARLEGUI  LOPE EZQUERRO  POPPE L. DE BOER 《Sedimentology》2012,59(5):1536-1567

An aeolian dune field migrating to the east encroached on the toes of alluvial fans in the Teruel Basin (eastern Spain) during a short interval in the Late Pliocene (ca 2·9 to 2·6 Ma), when Northern Hemisphere glaciation and strong glacial–interglacial cycles began. Preservation of the dune field was controlled by syn‐sedimentary activity of a normal fault. Ephemeral water discharge eroded aeolian sands and formed V‐shaped channels in which aeolian sandstone blocks accumulated. The incorporation of loose aeolian sand in wadi waters modified the sediment/water ratio, changing the physical properties of the flows as they penetrated the aeolian dune field. The erosion and cover of aeolian dune foresets by sheetflood deposits suggest that dune‐damming caused the intermittent ponding of water behind the dunes and its flashy release. The arid climate in the Late Pliocene western Mediterranean realm favoured the transport of windblown sediments from northern Africa and western Mediterranean land masses into the Mediterranean. The formation of the studied aeolian dune field (2·9 to 2·6 Ma) and possibly others (for example, the Atacama, Namib and Sahara deserts) correlates with a strong increase of the influence of obliquity, which can be attributed to the combination of a regional expression related to the reduced effect of precession due to a minimum in the long‐period (2·3 Ma) eccentricity cycle and a remote expression of the onset of the Northern Hemisphere glaciation.  相似文献   

黄河下游床面形态判别方法探讨          下载免费PDF全文

张原锋  申冠卿  VerbanckMA 《水科学进展》2012,23(1):46-52

基于床面形态控制数理论,结合已有水槽试验研究成果,分析了床面形态控制数与不同床面形态的对应关系,提出了包括沙粒弗劳德数及相对水深(水深与泥沙中值粒径之比, 下同)的床面形态参数, 论述了简化床面形态控制数的计算方法及适用范围,研究了床面形态控制数与床面形态参数之间的相互关系及适用性;结合黄河下游床面形态运动特征,建立了床面形态判别方法。研究认为床面形态控制数能够反映高、低能态区的水流阻力特征;床面形态控制数与床面形态参数之间的关系,既适用于室内水槽试验也适用于天然河流;建立的黄河下游床面形态判别方法,得到了野外实测资料的初步检验,能够用于黄河下游不同能态区床面形态的判别。  相似文献   

海岸沙丘表面现代风成沙地球化学元素分异的典型研究--以河北昌黎黄金海岸横向沙脊为例   总被引：2，自引：0，他引：2  

龙黎  董玉祥  孙忠 《沉积学报》2012,30(4):724-730

在我国海岸沙丘主要分布地区河北昌黎黄金海岸选取代表性的海岸横向沙脊为研究对象,对其典型断面上沙丘表面不同部位的21种地球化学元素的含量进行了比较分析。结果表明,Co、Zr和Mg三种元素在海岸沙脊表面不同部位的含量差异明显且与海滩沙相比含量差异较大,Cr、Pb、Ti、Nb、As、Mn、Zn和Ba等8种元素的含量差异程度中等,但Y、Ca、Fe、Na、Al、Sr、P、K、Rb和Si等10种元素的差异并不明显,而11种差异程度中等以上元素在海岸横向沙脊迎风坡脚、迎风坡、脊顶、背风坡、背风坡脚等部位的含量变化特征并不一致,呈现出不同的分异模式,其主要原因是受沉积环境、化学元素性质、粒度特征及营力的影响等。  相似文献   

基于GIS空间分析技术的新月形沙丘表面输沙率模型研究   总被引：2，自引：1，他引：1  

杜鹤强  韩致文  邓晓红  张扬  孙家欢 《中国沙漠》2011,30(4):815-823

 输沙率研究是风沙物理学与风沙工程学的重要内容。为了尝试GIS空间分析技术在新月形沙丘表面不同部位输沙率分布及模型建立中的应用,选取塔克拉玛干沙漠腹地典型孤立新月形沙丘,对其表面进行粒度采样和风速采样,并对沙丘表面的五个典型部位进行输沙率的采集。经过对风速数据归一化处理之后,根据粒度和风速采样特点,分别应用克里格方法和反距离方法对粒度和风速样点插值,得到新月形沙丘表面栅格形式的粒径分布和风速分布图。利用3种常用输沙率模型分别对沙丘表面5个典型部位进行输沙率计算,并与实测值进行对比。选取拟合优度最佳的Srensen模型,整合粒径和风速分布图,利用地图代数方法对沙丘表面输沙率分布进行计算,得到栅格形式的沙丘表面输沙率分布图。利用GIS的空间分析技术研究沙丘表面的输沙率分布,克服了传统定点观测的诸多不足。  相似文献   

Coastal Erosion Along the West Coast of the Taiwan Strait and It’s Influencing Factors   总被引：1，自引：0，他引：1  

Jianhui Liu  Feng Cai  Hongshuai Qi  Gang Lei  Lihua Cao 《中国海洋大学学报(英文版)》2011,10(1):23-34

Based on the field surveys and repeated cross-profile observations combined with the comparison of many years’ topog-raphic maps,this study shows the spatial variability and varying patterns of coastal erosion along the west coast of the Taiwan Strait.Regional differentiation in the Meso-Cenozoic coastal tectonics determined the irregular coastline and geological background for large-scale coastal erosion distribution.The intensity of coastal erosion on the west side of the Taiwan Strait is mild in the nort...  相似文献   

Factors influencing seed germination of Cyperus capitatus, inhabiting the moving sand dunes in southern Europe     

S. Redondo-Gómez  L. Andrades-MorenoR. Parra  E. Mateos-NaranjoA.M. Sánchez-Lafuente 《Journal of Arid Environments》2011,75(3):309-312

Cyperus capitatus Vandelli (Cyperaceae) is distributed in coastal sandy habitats and mobile dunes of south Europe. Its seed germination ecology is not known, despite its potential to be used in re-vegetation projects. Laboratory experiments were conduced to assess the effects of salinity, light regime, cold stratification and burial on seed germination of this species. Overall, increasing salinity delayed germination, increased seed dormancy and mean time to germination (MTG), and reduced final germination percentage, inhibiting it completely above 1% of salinity; although it did not affect seed viability. C. capitatus seeds exhibited their greatest germination at levels between 0 and 1% in non-stratified seeds, and between 0 and 0.5% for stratified seeds. Thus, the effect of salt was greater for stratified seeds at 5 °C. Germination in light/darkness conditions was similar to that in full darkness. Finally, burial in sand of C. capitatus seeds appeared to have a significant effect on cumulative percentage of germination. Seeds buried at depths greater than 2 and 3 cm showed a lower germination success than those on sand surface or buried at shallower depths. Burial also affected the beginning and speed of seed germination.  相似文献   

The effect of asymmetric dune roughness on tidal asymmetry in the Weser estuary     

Gerald Herrling  Marius Becker  Alice Lefebvre  Anna Zorndt  Knut Krämer  Christian Winter 《地球表面变化过程与地形》2021,46(11):2211-2228

The bed of estuaries is often characterized by ripples and dunes of varying size. Whereas smaller bedforms adapt their morphological shape to the oscillating tidal currents, large compound dunes (here: asymmetric tidal dunes) remain stable for periods longer than a tidal cycle. Bedforms constitute a form roughness, that is, hydraulic flow resistance, which has a large-scale effect on tidal asymmetry and, hence, on hydrodynamics, sediment transport, and morphodynamics of estuaries and coastal seas. Flow separation behind the dune crest and recirculation on the steep downstream side result in turbulence and energy loss. Since the energy dissipation can be related to the dune lee slope angle, asymmetric dune shapes induce variable flow resistance during ebb and flood phases. Here, a noncalibrated numerical model has been applied to analyze the large-scale effect of symmetric and asymmetric dune shapes on estuarine tidal asymmetry evaluated by residual bed load sediment transport at the Weser estuary, Germany. Scenario simulations were performed with parameterized bed roughness of symmetric and asymmetric dune shapes and without dune roughness. The spatiotemporal interaction of distinct dune shapes with the main drivers of estuarine sediment and morphodynamics, that is, river discharge and tidal energy, is shown to be complex but substantial. The contrasting effects of flood- and ebb-oriented asymmetric dunes on residual bed load transport rates and directions are estimated to be of a similar importance as the controls of seasonal changes of discharge on these net sediment fluxes at the Lower Weser estuary. This corroborates the need to consider dune-induced directional bed roughness in numerical models of estuarine and tidal environments.  相似文献   

Effects of sand burial on dune plants: a review     

Hao Qu  HaLin Zhao  RuiLian Zhou 《寒旱区科学》2014,6(3):0201-0208

Burial of different growth stages of plants （e.g., adult plants, seedlings and seeds） is frequent in dune ecosystems. The soil micro-environment, which differs from surface conditions, influences the survival and growth of dune plants. To sum up knowledge about the survival mechanisms of plants under sand burial and to promote practical rehabilitation of dune vegetation, we reviewed relevant published literature and concluded that： （1） Focus in recent years has been on impacts of sand burial on seed germination and seedling emergence. Generally, shallow burial increased seed germination and seedling emergence, but deeper burial was negative. Buried at the same depth, large seeds showed higher germination and seedling emergence rates, attributed to larger energy reserves. （2） Survival, growth and reproduction rates of dune plants show plasticity in response to sand burial. Long-term deep burial is fatal because it creates a physical barrier which overcomes the vertical growth of plants, reduces photosynthetic leaf area, and limits oxygen availability to roots. Modest burial, on the other hand, is advantageous for growth and reproduction of many dune plants, due to protection from excessive temperature and drought. （3） There are few reports concerning effects of sand burial on plant physiology, but a limited number of studies indicate that partial burial increases water use efficiency, chlorophyll content, transpiration rate and net photosynthetic rates. The antioxidant protective enzyme system and osmolyte balance were reported to be involved in the mechanisms of dune plant resistance to burial.  相似文献   

Morphometric analysis of aeolian bedforms in the Namib Sand Sea using ASTER data     

Joanna E. Bullard  Kevin White  Ian Livingstone 《地球表面变化过程与地形》2011,36(11):1534-1549

The ASTER Global Digital Elevation Model (GDEM) has made elevation data at 30 m spatial resolution freely available, enabling reinvestigation of morphometric relationships derived from limited field data using much larger sample sizes. These data are used to analyse a range of morphometric relationships derived for dunes (between dune height, spacing, and equivalent sand thickness) in the Namib Sand Sea, which was chosen because there are a number of extant studies that could be used for comparison with the results. The relative accuracy of GDEM for capturing dune height and shape was tested against multiple individual ASTER DEM scenes and against field surveys, highlighting the smoothing of the dune crest and resultant underestimation of dune height, and the omission of the smallest dunes, because of the 30 m sampling of ASTER DEM products. It is demonstrated that morphometric relationships derived from GDEM data are broadly comparable with relationships derived by previous methods, across a range of different dune types. The data confirm patterns of dune height, spacing and equivalent sand thickness mapped previously in the Namib Sand Sea, but add new detail to these patterns. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献