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1.
The interaction between fluvial and aeolian processes can significantly change surface morphology of the Earth. Taking the Horqin Sandy Land as the research area and using Landsat series satellite remote sensing images, this study utilizes geomorphology and landscape ecology to monitor and analyze the aeolian geomorphology characteristics of the Horqin Sandy Land. Results show that the sand dunes of the Horqin Sandy Land are mainly distributed on alluvial plains along the banks of the mainstream and tributaries of the Western Liao River, and the sand dune types tend to simplify from west to east and from south to north. The aeolian geomorphology coverage tend to be decreasing in the past 40 years, with an average annual change rate of 0.31%. While the area of traveling dunes decreased, the area of fixed and semi-fixed dunes increased. The fractal dimensions of various types of sand dune have all remained relatively constant between 1.07 and 1.10, suggesting that they are experiencing a relatively stable evolutionary process. There is a complex interaction between fluvial and aeolian processes of the Horqin Sandy Land, which plays a central role in surface landscape molding. Sand dunes on both sides of different rivers on the Horqin Sandy Land present certain regularity and different characteristics in terms of morphology, developmental scale, and spatial pattern. There are six fluvial-aeolian interaction modes in this area: supply of sand sources by rivers for sand dune development, complete obstruction of dune migration by rivers, partial obstruction of dune migration by rivers, influence of river valleys on dune developmental types on both sides, influence of river valleys on dune developmental scale on both sides, and river diversion due to obstruction and forcing by sand dunes. This study deepens our understanding of the surface process mechanism of the interaction between fluvial and aeolian processes in semi-arid regions, and provides a basis for researches on regional landscape responses in the context of global environmental change.  相似文献   

2.
“West Jilin Porovince” in ths paper means Zhenlai,Baicheng,Taonan,Da‘an,Tongyu,Fuyu,Songyuan,Qian‘an ,Chandling,also includes Gongzhuling,Shuangliao,Lishu,Siping and Nong′an which have been suf-fered from desertification.In west Jilin Province there are three sand zones passing through,they are Xiang(Xianghai)-Wu(Wlan Tug)sand zone,Hai-Fent sand zone,and Tao′er River right band sand zone.The desertification area of west Jilin Province is 819 100ha,making up 12.5% of the total land area.Among desertification types,in Jilin Province light desertification is the major,then is medium dersertification,hevey desertification is the least.According to the compare-son of the interpretation results of the Landsat images of the 1980s and 1990s by remote sensing and GIS techniques,it can be seen that the diesertification area in west Jilin Province basically didn′t change on the whole,only increased 6130ha,making up 0.8% of the desertification area,change scale is less than 1%.Evidently,desertification is con-trolled mostly,but some areas are continuing deterioration.The desertification process of China can be divided into three types according to origin nature,they are sandy steppe desertification,fixed sand area(sand land) activation and dunes transfer invasion.Reasons of desertification of West Jilin Province are analyzed,they include natural factors(such as material source factors,chimate factors) and artificial factors(such as destroying grass to reclaim,steppe decreasing greatly,illegally feeling shelter forest stands,constructing reservoir to influence eco-environment etc.).Some sugges-tions are put forward as follows:establishing the social project for ecological reconstruction of degenerated land;intensify-ing planning and management of land use,reverting farmland into forestland or pasture in a planned way.The key desertifica-tion control is to depend mainly on policy and management,then control techniques.  相似文献   

3.
SahelbioclimaticzonecrossNorthAfricabe-tweenl7oNandl3"Nborders,theSaharaDeserttothenorthandtheSudansavannatothesouth,beinganimportantfragileecologicalzoneintheworld.SincethesevereSudano-Saheliandroughtof1968-l973sandydesertificationhasresultedinaverymiserableconse-quencestolocalpeople,asaSahelcountryinwestAhica,theRepublicofMaliisoneofthecountriesmostseverelyaffectedbydroughtanddesertification,AccordingtotheinvestigationsoftheexpertgroupoftheLanzhouInstituteofDesertResearch,theChineseA-…  相似文献   

4.
The Tarim River Basin, located in the typical arid region, is one of the key regions of LUCC research in China and plays an important role in maintaining the sustainable development of the westem China. In recent years, the ecological environment of the Tarim River Basin has degraded greatly. In the lower reaches, in particular,the riverbed has been dried up for more than 20 years, which accelerated the desertification and has been a great threat to people‘s lives. Taking the section of the Tarim River between Qiala Lake and Taitema Lake as a typical region, an investigation on land cover changes was carried out with the support of remote sensing information of 1988 and 2000 respectively. The changes of land cover in this region were obtained: 1) Cropland tended to increase. 2)Urban or Built-up Area in 2000 was 324.4ha more than that in 1988.3) Waters expanded by 3476.51ha. 4) Woodland and Grassland decreased, while Barren Land increased by 3824.9ha. The total amount of land use/land cover change between 1988 and 2000 is small, which is only 0.355% of the total area. It shows that the developmental pace of the lower reaches of the Tarim River is relative slow. Based on these results, the authors assessed the landscape dynamics of this region and pointed out that the degree of desertification was strengthened and the landscape dominated by sand land was further characterized by salt desert.  相似文献   

5.
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6.
Wind and sand control are important factors in combating desertification and protecting oases. An oasis protective system can provide these benefits, but quantitative research on protection effects has been lacking to date. This researchdescribes an oasis protective system in the southeastern border of the Tengger Desert. The system consists of a sand barrier belt, a shrub and herbaceous plant belt, and a farmland shelter belt.The system was compared to a bare dunes area as the control zone. The study investigated windproof effect,sediment transport, and erosion through fieldobservations. Results showed that the roughness of the shrub and herbaceous plant belt, farmland shelter belt, and sand barrier belt were increased compared with bare dunes. The shrub and herbaceous plant belt provided the highest windproof effect values for the same wind velocity measurement height, and the windproof effect values for different protective belts were as follows: shrub and herbaceous plant belt farmland shelter belt sand barrier belt. The sand barrier belt provided effective wind and sand control at heights from 0 to 50 cm above the ground. The total sediment transport for each protective belt is as follows: bare dunes sand barrier belt shrub and herbaceous plant belt farmland shelter belt. The sediment transport decreased exponentially as the height increased. In the bare dunes and protective systems, the sediment transport is mainly within 30 cm of the ground surface. The wind erosion intensity for this protective system was as follows: bare dunes sand barrier belt shrub and herbaceous plant belt farmland shelter belt. This research offers quantitative evidence for how oasis protective systems can effectively intercept sand and prevent erosion in oases. The results of this study can be applied in similar regions.  相似文献   

7.
In the Songnen Plain, there are 330,000 ha of alkaline meadow, many sand sources such as fixed dunes, semi-fixed dunes and sand hills, and rich wind force resources as well. Sand has been stopped naturally and A neurolepidium chinense has grown on alkaline patch of the plain. If we make use of the natural law and set up manmade obstacles in alkaline patches, we can use accumulative sand to cover alkali, improve alkaline meadow, restore A neurolepidium chinense vegetation to develop animal husbandry.  相似文献   

8.
The survival of Dunhuang Oasis is largely determined by the evolution of sand dunes in the southern edge of the oasis, mainly composed of shield dunes and mega pyramid dunes, which occupy two-thirds and one-third of the area, respectively. However, few studies have focused on dynamics of these dunes, especially in terms of quantification. So the theoretical basis of sand-control engineering is relatively limited. Here we present the characteristics of dune dynamics of a shield dune and mega pyramid dune in the southern edge of Dunhuang Oasis during April 2014–April 2016 based on measurement data of a 3-D laser scanner. Results indicate that the volume of the shield dune decreased during the monitoring period of two years, and the gravity centers of the monitored shield dune moved windward, indicating that sand was transported toward the oasis. Conversely, the dune volume of the mega pyramid dune increased and the gravity center presented no prominent movement, indicating that the mega pyramid dune was relatively stable and its migration toward the oasis was not notable. Thus, compared with mega pyramid dunes, shield dunes in the southern edge of Dunhuang Oasis are identified as a more significant sand source endangering the protection of the oasis, and sand-control engineering should mainly focus on these shield dunes.  相似文献   

9.
1 INTRODUCTIONAccording to historical records, there has existed the large-area desert in the northwest of China for a long time, which formed in the geologic age and historical periods, and continuously evolved because of climate changes and human activities. Although a certain amount of achievement has been obtained since the 1950s, land desertification went on expanding quickly. For desertification by wind erosion, the average expansion speed was 1560km2 per year from the late 1950s …  相似文献   

10.
Barchan dune is one of the basic forms of eolian landform, it is usually moulded by high-concentration non-saturated wind-sand flow. The formation process of barchan dune begins from “wave-grain duality” of wind-sand movement, and goes through two developmental stages of sand material accumulating (high-concertration saturated wind-sand flow) and dune form moulding (high-concentration non-saturated wind-sand flow), i.e. the processes of dissipative increase and dispersive decrease. The scattered single barchan dunes on non-sandy bed surface have obvious characteristics of mobility and unstability (not including barchan sand hill). The formation of barchan dune in wind tunnel (its dune scale is one order of magnitude larger than sand ripple scale) is helpful to know the formation mechanism of barchan dunes. One of the series achievements supported by the National Natural Science Fundation of China (No. 49371009)  相似文献   

11.
Serious desertification caused by human activity and climate change, in addition to water loss and soil erosion related to arsenic sandstone in the Mu Us Sandy Land, lead to severe scarcity of soil and water resources, which causes worse local agricultural conditions accordingly. Many physical properties of arsenic sandstone is complementary with that of sand, arsenic sandstone is therefore supposed to be blended to enhance water productivity and arability of sandy land. Container experiments are carried out to study the enhancement of water holding capacity of the mixture, the blending ratio of arsenic sandstone and sand, and the proper size of the arsenic sandstone particles, respectively. The results of the experiments show that particle size of 4 cm with a ratio of 1 ： 2 between arsenic sandstone and sand are the proper parameters on blending. Both water content and fertility increase after blending. Water use efficiency in the mixture is 2.7 times higher than that in sand by the water release curves from experiments. Therefore, a new sand control and development model, including arsenic sandstone blending with sand, efficient water irrigation management and reasonable farming system, is put forward to control and develop sandy land so that water-saving agriculture could be developed. Demonstration of potato planting about 153.1 ha in area in the Mu Us Sandy Land in China indicates that water consumption is 3018 m3/ha in the whole growth period. It means that about 61% of irrigation water can be saved compared with water use in coarse sand without treatment. Recycle economic mode and positive feedback of sand resource-crop planting-soil resource are constructed, which changes sand into arable soil and make it possible to develop water-saving agriculture on it. The proposed model will be helpful for soil-water resources utilization and management in the Mu Us Sandy Land.  相似文献   

12.
Aeolian sand landforms in the Yarlung Zangbo River(YZR) valley are a special type of aeolian landform that has attracted the attention of many scholars. However, the spatial distribution as well as the formation mechanism of aeolian sand has rarely been reported with integrated studies. In this paper, for remote sensing interpretation, scanning electron microscopy(SEM), X-ray diffraction(XRD) and particle size distribution(PSD) methods were used to analyze the spatial distribution and the deposition characteristics of aeolian sand. Combined with wind data and topography, the main driving factors and the formation mechanism of aeolian sand landforms were also examined. In the middle reaches of the YZR valley, there is a total of 2324.43 km~2 of aeolian sand, especially on the north bank of the wide valleys. In different wide valleys, the aeolian sand landforms exhibit a decreasing trend from the upstream to the downstream regions in both the area and expansion rate of aeolian sand. The cyclonic vortexes generated by the westerly winds and glacial winds are the main driving factors for transporting alluvial sand to the riverbank areas to form aeolian dunes. There are three main types of sand dunes in the river valley: climbing dunes, lee dunes and circumfluent dunes. Climbing dunes and lee dunes are mostly located west of the Jiacha Gorge, and the circumfluent dunes are mostly located east of the Jiacha Gorge.  相似文献   

13.
Soil organic carbon (SOC) was considered to be a key index in evaluation of soil degradation and soil C sequestration. To discuss the spatial-temporal dynamics of SOC in arable layer in reversed desertification area, a case study was conducted in Yulin City, Shaanxi Province, China. Data of SOC were based on general soil survey in 1982 and repeated soil sampling in 2003. Soil organic carbon content (SOCC) was determined by K2Cr3O2-FeSO4 titration method, and soil organic carbon density (SOCD) was calculated by arithmetic average and area weighted average method, respectively. On average, SOCC and SOCD of the arable layer in the study area from 1982 to 2003 had increased 0.5 Ig/kg and 0.16kg/m2, respectively. Considering main soil types, the widest distributed Arid-Sandic Entisols had lowest values and increments of SOCC and SOCD during the study period; while the second widest Los-Orthic Entisols had higher values and increments of SOCC and SOCD, compared to the mean values of the whole region. The results indicated that reversed desertification process was due to the modification of land use and management practices, such as natural vegetation recovery, planting grass, turning arable land to grassland, and soil and water conservation etc., which can improve SOCC and SOCD and thus enhance soil C sequestration.  相似文献   

14.
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   

15.
荒漠化被列入威胁人类生存的十大环境与发展问题之一,中国作为世界上荒漠化严重的国家,荒漠化形势十分严峻。本文通过遥感手段,以中国陆域国土范围（除台湾、香港和澳门）的31个省、市、自治区为研究区域,对1975年、2000年与2017年研究区数据进行沙化、盐渍化、水蚀荒漠化专题因子时空演变的综合研究,根据地域分异、发生学及多级序列等原则将将中国划分为8个荒漠-荒漠化区,42个荒漠-荒漠化亚区和36个荒漠-荒漠化小区。以不同时期荒漠化土地类型图为依据,采用荒漠化面积变化量与荒漠化重心迁移轨迹指标进行荒漠化演化分析。为具体说明不同区域荒漠化程度,本研究根据一定时期内荒漠化土地面积增加或减少的百分比将荒漠化演化分为7种类型,通过分析得到不同荒漠化区域的时空演化及不重心迁移,据此提出中国荒漠化的重点治理目标区及防治建议。研究结果表明：① 中国荒漠、荒漠化土地种类较多,重度荒漠化面积25.18×104 km2,占荒漠化总面积的19.59%;② 1975-2017年,中国荒漠化发生明显逆转,与1975-2000年相比,2000-2017年全国的荒漠化强度显著下降,原因是荒漠化加重区面积减少以及荒漠化减弱区面积增加;③ 1975-2000年与2000-2017年,各区内荒漠化重心点坐标迁移具有同向性。本研究在分析荒漠化土地分布、形成和演变机制的基础上,进行了荒漠化分区。通过对不同荒漠化地区的面积百分比变化的比较,得到了不同时期荒漠化的时空演化模式,并分析了荒漠化演化的特点和差异。  相似文献   

16.
In order to study the spatial-temporal change and environmental management of regional karst LUCC (land use and land cover change) and its causative environmental effect-rocky dcsertification by integrating qualitative analysis and quantitative analysis, and relying on RS, GIS and GPS (3S) techniques, karst land rocky derification dynamic monitoring and visualization management information system (KLRD.DMVM.IS) is framed, which includes design aim and structure model, function design, database design and model system design. The model system design gives priority to dynamic monitoring, drive force diagnosis, comprehensive evaluation and decision support of karst rocky desertification. From the viewpoint of model type, mathematic expression and its meaning, the dynamic monitoring models are concretely devised to reflect the spatial and temporal changing features and the trend of karst LUCC and rocky desertification. Taking Du‘an Yao Autonomic County of Guangxi as an example, the KLRD.DMVM.1S is systematically analyzed in the application of the process and trend of karst LUCC and rocky desertiflcation in Du‘an County, and it provides the technical support for the study on karst land rocky desertification.  相似文献   

17.
桂林市电子沙盘设计及其功能   总被引：4，自引：1，他引：3  
桂林市电子沙盘的开发采用了3S技术、多媒体技术和数字化技术, 它以数字化的地形图为基础数据源, 建立数字高程模型; 以卫星遥感数字图像为三维景观的表层粘模。电子沙盘具有二维平面-三维立体图对照显示,任意调整观察的位置、高度、方位、视角等功能, 并可以按预设的路线在空中模拟飞行观察, 给人亲临其境的感觉。同时, 它具有绘制剖面、求算任意区域地表面积和土石方量(水库库容)等功能, 突破传统沙盘的概念。  相似文献   

18.
ＴｈｅＹａｒｌｕｎｇＺａｎｇｂｏＲｉｖｅｒ，ａｌａｒｇｅｒｉｖｅｒｗｉｔｈｈｉｇｈｅｓｔａｌｔｉｔｕｄｅｉｎｔｈｅｗｏｒｌｄ，２０５７ｋｍｉｎｌｅｎｇｔｈ，ｆｌｏｗｓｔｈｒｏｕｇｈｔｈｅｓｏｕｔｈｅｒｎｐａｒｔｏｆｔｈｅＱｉｎｇｈａｉＸｉｚａｎｇ（Ｔｉｂｅｔ）Ｐｌａｔｅａｕｆｒｏｍｗｅｓｔｔｏｅａｓｔａｎｄｄｒａｉｎｓａｎａｒｅａｏｆ２４０４８０ｋｍ２ｂｅｉｎｇａｓｅｎｓｉｔｉｖｅａｒｅａｔｏｔｈｅｅｎｖｉｒｏｎｍｅｎｔａｌｃｈａｎｇｅｓ（Ｇｕａｎｅｔａｌ．，１９８４；Ｙａｎｇｅｔａｌ．，…  相似文献   

19.
Widespread aeolian sediments have been found in the middle reaches of the Yarlung Zangbo River, China. The grain-size characteristics of sediments from Cha'er Section in the area were analyzed. The results show that the section include one stratum of paleo-mobile dunes, four strata of paleo-semi-fixed dunes, two strata of paleo-fixed dunes, one stratum of sandy immature soils. The paleo-mobile and paleo-somi-fixed dune sand in this section are similar to modern aeolian sand in either grain-size composition or Mz and σ distribution. Compared the above types of dunes each other, the content of sand substance decreases, while the content of silt and clay increases for palco-fixed dunes and sandy immature soils. Combined with age data for each stratum, the analysis shows that these strata are the products of climate changes and the evolution of aeolian landforms. The evolutionary sequence of the paleoclimate and of acolian activities in the valley since 8600 yr B.P. reveals four stages: 8600-5700 yr B.P., when the paleoclimate was cold and dry, with strong winds, thereby activating dunes; 5700-3600 yr B.P., when it was warm and wet, with weak winds, causing dunes to undergo soil-forming processes; 3600-1900 yr B.P., when climate shifted from cold-dry with strong winds to warm-wet with weak winds, and activated dunes were fixed again; and 1900 yr B.P. -present, when the climate became fine, with weak winds, fixing dunes again.  相似文献   

20.
Wind erosion, or the transportation and deposition of sand into desert dunes and aeolian loess, is one of the most important aeolian activities. The progression of aeolian landforms expands arid and barren landscapes, leading to the degradation of adjacent areas. The Gonghe Basin, as a typical plateau with abundant sand sources, is highly sensitive to changes in the local climate conditions. In order to quantify the spatial-temporal variations in the aeolian landforms in the Gonghe Basin, we conducted field surveys and also analyzed twelve remote sensing(Landsat5 TM and Landsat8 OLI) images that sample the Gonghe Basin from 1989 to 2019. In the Gonghe Basin, we identified aeolian landforms such as climbing dunes on the windward slopes of the foothills, checkerboard dunes in the southeastern part of the basin, flat dunes, parabolic dunes and crescent dunes on the east and west sides of Longyangxia Reservoir, shrubby sandbanks on the valley slope in Shazhuyu, Tanggemu, and Indel, and sandy thickets at the bottom of the valley near the Dalian Sea, the Longyangxia Reservoir, and the tributaries of the Yellow River. From 1989 to 2005, the area of theaeolian regions expanded by 816.7 km~2, with an annual conversion rate of 0.05%. From 2015 to 2019, the area of the aeolian regions shrunk by 2411.9 km~2, with an annual conversion rate of-0.15%.The number and size of the fixed and semi-fixed dunes(e.g. the shrubby sandbanks on the valley slope and the sandy thickets at the bottom of the valley) were more stable than those of the mobile dunes(e.g. the checkerboard dunes, the flat dunes, the crescent dunes, the parabolic dunes, and the climbing dunes). The fixed and semi-fixed dunes were arranged in an irregular ring shape, and the location of the center of gravity of this ring did not change significantly from 1989 to 2019; in this time, the mobile dunes migrated to the northwest.  相似文献   

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