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1.
塔克拉玛干沙漠腹地高大复杂纵向沙垄区简单横向沙丘形态特征的空间变异 总被引：1，自引：0，他引：1
为了探讨小尺度风沙地貌形态的空间变异过程,对塔克拉玛干沙漠腹地高大复杂纵向沙垄横断面上简单横向沙丘形态特征进行了研究。沙丘形态野外测量采用RTK(real-tim e k inem atic)技术,并通过南方测绘软件(South Survey)量算形态特征参数。结果表明:简单横向沙丘形态特征参数及其相互关系具有空间变异性。在8个地貌部位之间,沙丘形态特征参数(不包括迎风坡度)存在显著性差异,主要体现在:垄顶、沙垄背风坡、其他地貌部位(包括垄间地和沙垄迎风坡)三者之间的差异。地貌部位、输沙风强度以及沙丘活动强度是驱动沙丘形态空间变异的因素。沙丘高度与翼展度余弦有负对数关系,发育指数与高度、迎风坡度成负线性相关,这些相关性的显著程度在垄顶、背风坡较高,在垄间和迎风坡较低。 相似文献
2.
毛乌素沙地东南缘不同类型沙丘土壤水分分布特征 总被引：3，自引：1，他引：2
通过对横山县境内毛乌素沙地东南缘的实地考察,根据植被类型和植被覆盖度,将沙丘分为裸露流动沙丘、灌木覆盖沙丘、乔木覆盖沙丘,分别在各类沙丘不同地貌部位实施4 m深度钻孔取样,并进行含水量测试和粒度分析,研究沙地土壤含水量变化。结果表明:对于垂直方向0～4m深度的沙地、灌木和乔木覆盖沙丘平均含水量变化为:丘间洼地>迎风坡>背风坡,而裸露流动沙丘平均含水量变化为:丘间洼地>背风坡>迎风坡;不同类型沙丘在各地貌部位不同层段含水量变化差异明显,变化趋势不统一。沙丘的地貌部位相同,地表的植被类型和覆盖度差异是影响沙地土壤含水量的重要因素,测试结果显示,迎风坡含水量为:灌木覆盖沙丘>乔木覆盖沙丘>裸露流动沙丘;背风坡含水量为:灌木覆盖沙丘>裸露流动沙丘>乔木覆盖沙丘;丘间洼地含水量为:灌木覆盖沙丘>乔木覆盖沙丘>裸露流动沙丘。灌木覆盖沙丘土壤含水量变异系数最大,水分含量在不同层位波动较大,裸露流动沙丘和乔木覆盖沙丘含水量波动差异较小。沙丘上生长的灌木和乔木明显地改变了沙丘含水量的变化特征,灌木比乔木对沙丘含水量及其垂向变化的影响更显著。灌木对地表大气中的粉尘有较强的拦截能力,灌木沙丘平均的粉砂和黏土含量高,灌木的覆盖有利于沙地的土壤化进程和保持沙地水分,在沙地绿化过程中,应充分考虑灌木植物的作用。 相似文献
3.
黄土高原坡度转换图谱研究 总被引：9，自引：0，他引：9
选择代表黄土高原典型地貌类型的样区,应用地学信息图谱的理论和方法,探讨了坡度信息图谱的定义、表现形式及存在原因等。经过反复试验、分析和验证,找到一个具有较理想精度的适用于黄土高原不同地貌类型的坡度转换图谱。实现对基于1∶5万地形图25m空间分辨率的DEM提取的地面坡度统计值的误差纠正,以及不同空间尺度下的DEM地面坡度精度提取。 相似文献
4.
新月形沙丘和抛物线沙丘可以相互转化和共存,对共存区地貌特征的研究有助于对其形成原因的理解和为防沙治沙提供科学依据。本文基于Esri历史影像服务,对浑善达克沙地西部新月形沙丘和抛物线沙丘共存区3个时期（2008年1月15日、2011年6月4日和2016年9月20日）的沙丘形态参数进行了提取,并计算了沙丘的移动方向和移动速度。结果表明：典型新月形沙丘集中分布于沙地西部的15个与干湖盆有关的区域,雏形新月形沙丘和雏形抛物线沙丘则依次分布在干湖盆外围,干湖盆的出现是浑善达克沙地典型新月形沙丘发育的关键因素,对湖泊干涸引起的沙漠化应引起足够重视。对共存区最典型的5区分析发现,典型新月形沙丘和雏形新月形沙丘在涉及到两翼的形态参数分布模式上与雏形抛物线沙丘有明显差异。进一步对沙丘形态参数间的相关性分析发现,从新月形沙丘向抛物线沙丘的转变过程中,迎风坡长、背风坡长和底面积的变化具有继承性,两翼在该过程中变化最大。此外,3类沙丘的移动方向在数值上差异不大并与合成输沙势方向（RDD）的变化一致,但三者的移动速度差异明显,且影响不同类型沙丘移动速度的因素也不相同。其中,植被对植被覆盖状况相对良好的雏形抛物线... 相似文献
5.
塔克拉玛干沙漠的大地貌格局是高大复合沙垄和宽广垄间地相间分布,而垄间地是研究简单沙丘发育过程的良好试验场地。基于Google Earth影像,以分形理论为基础,对塔克拉玛干沙漠腹地复合纵向沙垄区垄间地上覆沙丘在主导风方向上的分形特征进行了分析,结果表明：① 垄间地沙丘形状指数（面积-周长关系）的标度-频度双对数关系非常显著,分形关系客观存在,并且不受统计时所用标度的影响;② 垄间地各类沙丘的分维值存在差异,其中,饼状沙堆和沙片分维值最大（1.337）,新月形沙丘次之（1.170）,简单线性沙丘最小（1.087）;③ 垄间地沙丘分维值的空间差异较大,在1.187~1.656,其分维数：背风坡脚（1.24）＜垄间地中部（1.40）＜迎风坡脚（1.50）,变异系数为0.106;④ 垄间地沙丘稳定性指数与分维值的空间分布相反,即背风坡脚（0.26）＞垄间地中部（0.16）＞迎风坡脚（0.10）;⑤ 垄间地沙丘分维值空间差异主要与沙丘发育程度有关,其中,风信是动力基础,沙源是物质基础。在流动沙漠,沙丘分形维数可以作为反映其风沙环境特征的定量指标。 相似文献
6.
库姆塔格沙漠南部的风积地貌特征 总被引：10，自引：0，他引：10
通过考察结果和TM影像解译,库姆塔格沙漠的东南分布高大的沙山,沙丘形态复杂;南部和西南缘分布有多条南北走向的荒漠沟谷,两岸分布沙垄,高18~65m,垄脊点(金字塔型)线交错,沙垄走向与沟的走向一致,阶地上覆盖一层深色矿物组成的砂砾(粒径3~1mm)。沙漠的中心区域,孤立的新月型沙丘、沙丘链占优势。下伏地形强烈影响着库姆塔格沙漠的风沙地貌形态。沙漠南部的低山、阿尔金山及其山前洪积沟谷形成的沟谷效应,塑造了沙漠南部复杂的地貌形态。沙漠沙丘砂的粒径由南向沙漠中心减小,0.25~0.05mm细砂占80%左右。 相似文献
7.
塔里木沙漠公路在复合型纵向沙垄区的道路沙害 总被引：7，自引：0，他引：7
塔里木沙漠公路穿越高大复合型纵向沙垄段２７５ｋｍ,占到穿越流动沙漠总长度的６１．６％,公路沙害的类型和程度因地貌部位不同而异。通过大量野外调查和观测,并结合成因地貌分析,给出高大复合型纵向沙垄区典型地貌部位的主要沙害形式。 相似文献
8.
库姆塔格沙漠综合考察的主要进展 总被引：4，自引：0，他引：4
通过对库姆塔格沙漠的实地观测、样品分析和资料收集,获得了沙漠地区的基础数据。沙漠面积约2.29×104km2(2001年),沙漠存在向东南方向移动和周边扩大的趋势;库姆塔格沙漠沙丘形态以新月形沙丘链为主,羽毛状沙丘为特色,星状和其他复合型沙丘大量分布的特点;羽毛状沙丘的"羽轴"是一种较特殊的复合型沙垄,由单个新月形沙丘前后相连,在沙垄和沙垄之间的沙平地有地形起伏,形成较宽大的弧形沙埂,基本与沙垄走向垂直,由这些沙垄和沙埂组成了独特的羽毛状沙丘;沙漠内部羽毛状沙丘分布区全年盛行东北风,全年平均风速5.94m/s,年总输沙势944.46 VU;调查记录了沙漠区107种植物和79种脊椎动物,发现野骆驼在沙漠西部的水源地,3种稀有荒漠植物的新分布区;提出沙漠最早形成于70万年的中更新世。 相似文献
9.
科尔沁沙地坨甸交错区土壤水分的空间变异规律 总被引：3，自引：0，他引：3
科尔沁沙地沙丘-草甸相间地区,地貌形态多样、土地利用类型众多,从而导致土壤水分空间分布的复杂性。通过对科尔沁沙地典型沙丘-草甸相间地区的调查取样与试验分析,运用统计学理论和方法,研究土壤水分的空间变异性及其空间分布规律。结果表明：水平方向上,土壤水分总体表现为草甸地大于沙丘地,过渡带介于两者之间。就草甸地而言,植物生长越好,其土壤水分越高,保水持水性能也越好;沙丘地则与之相反,植被最稀疏的流动沙丘,其土壤含水量大于半流动半固定沙丘与固定沙丘,且有良好的储水条件。垂向上,高覆盖草甸、低覆盖草甸和农田（草甸）土壤含水量在地表下0～40 cm波动最大,40～160 cm随深度增加而递增;流动沙丘、半流动沙丘和固定沙丘土壤含水量随深度增加呈微弱加大趋势。林地、撂荒地、农田（沙丘）变化程度居中。从空间分布看,研究区中东部土壤水分偏大,且向南北两侧区域递减。 相似文献
10.
为探究沙丘形态数据集构建及自动分类方法,解决沙丘形态信息数据库缺失等问题,以内蒙古西部典型沙丘为研究对象,通过无人机正射影像技术采集6种典型沙丘形态数据,并结合GF-2号遥感数据采用数据增强方式构建沙丘形态数据集。通过迁移学习策略的VGGNet和ResNet模型对沙丘形态的深层语义特征进行解析与学习,自动获取更具有代表性的图像纹理特征,以此提出一种基于卷积神经网络(CNN)提取不同沙丘形态特征自动分类的方法。结果表明,基于迁移学习的VGG16模型在四种模型中分类准确率最高,达到88.14%;优化后的ResNet18模型与ResNet50模型的分类精度分别从84.04%、85.25%提升到92.79%、88.91%;优化后的ResNet18+模型表现出最佳的分类效果,准确率达到92.79%,更适用于沙丘形态的高精度自动分类。 相似文献
11.
The dynamical processes of a typical linear dune including morphological features, dune ridge swing range and crest height were investigated at different monitoring periods in the hinterland of Tengger Desert. The results indicated that the development of linear dune depends on not only the northwesterly prevailing wind, but also the winds from northeast and southwest. The dune ridge swayed along its fundamental strike and took on an eastward movement gradually. The original dune strike was NW70° on August 3, 1994, and then changed to NE15° on April 21, 2001. The dune crest increased by 1.8 m longitudinally, which manifested strong wind-blown sand activities in this region. Wind erosion frequently occured at the bottom of sand dune, while sand accumulation appeared on its mid-upper section. The mean wind erosion depth was 25 cm on the bottom of linear dune and the height difference of the control points on the dune's ridge was 1.13 m. Although the linear dune swayed laterally, the horizontal displacement of its ridge moved eastward 5.8 m averagely. The swing range of the dune crest line is very distinct, with a maximum value of 13.2 m. The highest site on the K-profile swayed on both sides of the dune ridge and the heights were 19.88 m at the control point K5, 19.61 m at K6 and 19.05 m at K7, respectively. The results indicated that the lateral swing of the linear dune was distinct under the northwesterly wind and it moved toward east gradually. 相似文献
12.
PANG Yingjun 《干旱区科学》2020,12(5):887-902
The seif dune field over the gravel desert surface in the eastern margin of the Kumtagh Desert is a valuable experimental site for the observation of dune formation and dynamics. We used high-resolution remote sensing and station observation approaches, combined with wind and grain size data, to study the characteristics of the aeolian environment and the morphologies of and dynamic changes in seif dunes. We observed the ratio of the resultant drift potential (RDP) to the drift potential (DP), which was 0.37, associated with an obtuse bimodal wind regime. The drift potentials in the west-northwest (WNW) and east-northeast (ENE) directions were dominant, and the angle between the two primary DP directions was 135.00°. The dune orientations ranged from 168.75°-213.75°, which were parallel to the resultant drift direction (186.15°). The dune lengths ranged from 51.68 to 1932.11 m with a mean value of 344.91 m. The spacings of the dunes ranged from 32.34 to 319.77 m with a mean value of 93.39 m. The mean grain size of the sediments became finer, and the sorting became better from upwind tail to downwind tip, which indicated that the sediment of the seif dunes in the study region may be transported from northward to southward. The rate of increase in the length, the mean longitudinal migration rate of the dune tail, and the mean longitudinal extension rate of the dune tip (also called elongation rate) were 4.93, 4.63, and 9.55 m/a, respectively. The mean lateral migration vector of the seif dunes was approximately 0.11 m/a towards the west (-0.11 m/a), while the mean amplitude of lateral migration was 0.53 m/a, ignoring the direction of lateral migration. We found that the seif dune field formed first beside seasonal rivers, which can provide sediment, and then expanded downwind. 相似文献
13.
塔克拉玛干沙漠腹地沙尘暴过程贴地层梯度输沙样粒度特征分析 总被引：2，自引：0，他引：2
利用2007年4月22日塔克拉玛干沙漠腹地一次沙尘过程采集的贴地层梯度输沙样,应用Malvern MS2000激光粒度分析仪进行实验测量。结果显示:平均粒径在100μm附近分布,按梯度层阶越向上颗粒分选越好,粒度曲线呈单峰正偏,极细沙比重最大。对比两个采样点,位于沙丘顶部的B点比位于平坦沙地的A点粒度分布范围更广。 相似文献
14.
Litter phosphorus(P) return is important to maintain the P cycle and balance in the sandy land of arid areas.In this study,we determined the loss and return of litter P in sand dune areas and elucidated their relationship.We investigated litter production and litter P amount,and simulated leaf litter moving dynamics to understand the relationships between the loss of litter P and the total litter P,and between the return of litter P and the total litter P in active(AD),semi-stabilized(SSD) and stabilized(SD) dunes in Inner Mongolia,northeastern China.The vegetation litter P was 12.6,94.5,and 201.6 mg P/m2 in AD,SSD,and SD,respectively.A significant movement and loss of leaf litter P with time occurred on the three types of sand dunes.As a result,the loss of P was 7.4,46.9,and 69.8 mg P/m2 and the return of P was 5.5,47.6,and 131.8 mg P/m2 in AD,SSD,and SD,respectively.The relationship between both loss and return of P and total litter P in AD,SSD,and SD was revealed by linear regression.The slope of the regression line indicated the rate of loss or return of litter P.From AD to SD,the loss rate showed a declining slope(0.52,0.32,and 0.17 for AD,SSD,and SD,respectively),and the return rate showed a rising slope(0.48,0.67,and 0.83 for AD,SSD,and SD,respectively).The loss of litter P should be regarded in the local management of vegetation and land in sand dune areas.Improved vegetation restoration measures are necessary to decrease litter P loss to maintain the stability of ecosystems in sand dune areas. 相似文献
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16.
Riverine sand dunes develop as a result of fluvial-aeolian interactions. The primarily barchan dune chains along the Xiangshui River (a branch of the Xar Moron River in the western part of the Horqin Sandy Land of China) form a typical riverine dune field. We collected a series of samples from the riverine sand dunes parallel to the direction of the prevailing wind and investigated the sand sources and formation mechanisms of these dunes by determining the grain size, heavy mineral content and optically stimulated luminescence (OSL) of the samples. The sand of the near-river dunes was coarser than the sand of the dunes distant from the river, indicating that coarse sand of the valley mainly deposited on near-river dunes. The heavy mineral analysis suggested that wind-sand activity levels were intense on the upwind dunes, but relatively weak on the downwind dunes. This indicated that the sand sources for the near-river dunes were more abundant than those of the distant dunes. Our OSL analysis of samples suggested that the deposition rates on dunes near the river were greater than the deposition rates on dunes distant from the river. The development of dunes along the river indicated that the river played an important role in dune formation and development. In addition, airflow fluctuation and the formation of the waveform dunes had a type of feedback relationship. Grain size, heavy mineral and OSL analyses are widely used methods in wind-sand research. Sand dune grain size characteristics reflect the effects of airflow on the transport and separation of sand materials, as well as the physical characteristics of the sand sources. Heavy mineral characteristics are often used to investigate the relationships between sediments and sand sources. OSL indicates dune age, revealing formation of dunes. Therefore, it is useful to explore dune sand sources, as well as the mechanisms underlying dune formation, by determining grain size, heavy mineral content and OSL. This study investigated the sand sources of riverine dunes and provided new information about riverine dune formation and development. 相似文献
17.
为了防止沙漠化的进一步扩展,于1983～1995年期间,在鄂尔多斯地区飞播了 12万hm2,在这里使用138个飞播区的调查数据,首先对适宜飞播植物种和合理的播种量进 行了探讨,得到如下结论:①在鄂尔多斯地区适宜飞播的植物种有杨柴、籽蒿、沙打旺、草苜蓿。 ②由于种子处理技术的应用,低播种量6.0-7.0kg/ha取得了良好的飞播成效。其次用Ⅰ类 数量化理论对播种时间、沙丘高度、沙丘密度、播前自然植被覆盖率与播后植被覆盖率的关系 进行了探讨,得到如下结论:①适宜的播种时间为5月25日-6月25日。②适宜的播区立地 条件为沙丘平均高度为10m以下,沙丘密度低于75%,播前自然植被覆盖率为12-25%。 相似文献
18.
Grain size distribution at four developmental stages of crescent dunes in the hinterland of the Taklimakan Desert,China 总被引：2，自引：0，他引：2
Although scientists have performed many studies on crescent (barchan) dunes in the Taklimakan Desert,few studies reported the changes in grain size at different development stages of crescent dunes.In order to evaluate the changing trends of surface sediment grain size with dune development,we investigated the grain size characteristics at four developmental stages (oval sand pile,shield dune,incipient crescent dune and mature crescent dune) of crescent dunes by measuring the morphology of sand dune and observing the near-surface wind regime.The dunes have developed in a wide inter-dune corridor between high compound longitudinal ridges in China's Taklimakan Desert.The surface sediments at four developmental stages of the crescent dunes were primarily composed of fine sands,followed by very fine and medium sands.Mean grain sizes ranged from 2.8 to 3.1 φ,with a unimodal distribution.The sands were moderately well-sorted,their distribution varied from platykurtic to very platykurtic,and symmetrical or skewed towards the fine particles.From oval sand piles through shield and incipient crescent dunes to mature crescent dunes,incipient grain size gradually increased,particles became finer,sorting became better,kurtosis and skewness increased.Grain sizes on the surface layer became coarser upwards from the toe of the windward slope and then became finer towards the bottom of the leeward slope.We found that the coarsest particles at different positions at the four developmental stages were different.The coarsest particles were distributed at the top of the oval sand piles and shield dunes,versus at the middle of the windward slope of the incipient and mature crescent dunes.Correlations between the mean grain size and other grain size parameters showed that as mean grain size became finer,sorting became better and kurtosis became wider,but skewness changed only slightly.In addition,grain size variation in the surface sediments correlated with the movement speed of the dunes in the study area.In the open ground among tall-complex longitudinal ridges in the hinterland of the Taklimakan Desert where aeolian environment is characterized by comparatively strong wind and unsaturated sand flow,faster dune movement corresponded to coarser grain size. 相似文献
19.
The areas used to be covered by shifting sand dunes have been reclaimed rapidly in recent years. However, it is a challenge to reclaim high sand dunes because it is rather costly to level the high dunes to gentle arable lands. In this study, a wind guide plate was used to change the characteristics of natural wind to level the sand dunes. The use of wind energy could significantly increase the efficiency of dune leveling and decrease the cost. Low wind velocity is a typical characteristic in Ulan Buh Desert of China where the average wind speed is much lower than the threshold velocity for sand movement. The experiment of this study was conducted to accelerate the wind velocity by a wind guide plate to level a sand dune. Results show that the threshold velocity for sand movement is 3.32 m/s at 10 cm above the sand surface in Ulan Buh Desert. A wind guide plate set at an angle less than 50° could significantly increase the wind velocity. The wind velocity could be accelerated up to the threshold velocity for sand movement behind a plate when the plate is at the angles of 20°, 25°, 35° and 40°. The most significant acceleration of wind velocity appears at 1.5 and 3.0 m behind the plate with an angle of 25°. An obvious wind velocity acceleration zone exists behind the wind guide plate when the angles are at 25°, 35°, 40° and 45°, with the most obvious zone under the angle of 45°. The results also show that the total amount of sand transferred over the experimental period increased by 6.1% under the effects of wind guide plates compared to the sand moved without wind guide plates. The results of the study will provide theoretical and practical supports for desert management in sand dune areas. 相似文献