EN中文

Journal of Resources and Ecology >

2021 , Vol. 12 >Issue 1: 124 - 135

DOI: https://doi.org/10.5814/j.issn.1674-764x.2021.01.012

Human Activities and Ecosystem

Overview of the Measures and Techniques Used to Protect Traffic Lines against Shifting Sands in China

  • MA Ning , 1, 2, 3 ,
  • GUO Qun 1, 2, 4 ,
  • LI Yu 5 ,
  • LI Shenggong , 1, 2, 3, 4, *
Expand
  • 1. Key Lab of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
  • 2. National Ecosystem Science Data Center, Beijing 100101, China
  • 3. Sino-Danish College, University of Chinese Academy of Sciences, Beijing 100190, China
  • 4. College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100190, China
  • 5. Key Lab for Resources Use and Environmental Remediation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
*LI Shenggong, E-mail:

MA Ning, E-mail:

Received date: 2020-06-08

  Accepted date: 2020-09-03

  Online published: 2021-03-30

Supported by

Strategic Priority Research Program of Chinese Academy of Sciences(Pan-TPE)

Strategic Priority Research Program of Chinese Academy of Sciences(XDA2003020202)

National Natural Science Foundation of China(31961143022)

Fold

Abstract

Shifting sands are one of the main contributors to desertification in China. This paper briefly reviews the measures and techniques which are used to protect traffic lines by stabilizing and fixing sands in the desert and desertification-affected arid and semi-arid areas in north China. We introduce the types and features of these measures and techniques, including mechanical, chemical, and biological measures, and outline how they have been applied in different areas and in different traffic lines over the past six decades, from 1950s to 2010s, taking the Baotou-Lanzhou railway, the Qinghai-Tibet railway, and the Tarim Desert highway as examples Mechanical measures such as erecting sand-retaining wind walls and placing straw checkerboards have proved to be very efficient for stabilizing shifting sands and protecting traffic lines that pass through the desert areas. Chemical measures are not widely used in the current sand fixing systems because of their high cost and potential pollution risks. Biological measures are preferred because they exhibit much better sand fixation performance and longer duration than the former two types of measures despite their relatively high cost. A combination of different measures is usually adopted in some areas to attain better sand-fixing effects. Stabilizing sand dune surfaces with mechanical measures or irrigation from underground water or river if available helps early recruitment of some drought-tolerant plants (xerophytes). We also point out the restrictions for existing sand-fixing measures and techniques and future research orientation. This review has implications for addressing eco-environmental issues associated with infrastructure construction that is part of the Belt and Road Initiative in desert and desertification-affected arid and semi-arid areas in the Mongolian Plateau.

Key words： traffic lines; desertification; shifting sands; wind erosion; sand fixing system

Cite this article

MA Ning , GUO Qun , LI Yu , LI Shenggong . Overview of the Measures and Techniques Used to Protect Traffic Lines against Shifting Sands in China[J]. Journal of Resources and Ecology, 2021 , 12(1) : 124 -135 . DOI: 10.5814/j.issn.1674-764x.2021.01.012

1 Introduction

The “Belt and Road Initiative (BRI)” was proposed in 2013 by the Chinese government with the aim of building a trade and infrastructure network connecting Asia with Europe and Africa along the ancient trade routes of the Silk Road. In 2014, the Mongolian government launched the “Steppe Road Initiative (SRI)”, which includes a 997-km-long highway linking China and Russia and 1100 km of power transmission lines. Under the context of the BRI and SRI China-Mongolia-Russia Economic Corridor, one of the six economic corridors passes through the arid and semi-arid areas with vast deserts in both China and Mongolia (the Mongolia Plateau) which experience severe desertification due to human activities as well as climate change. However, frequent sandstorms in this hot and dry climate may bring about considerable harm to the construction and operation of transportation facilities in the Corridor. Therefore, it is essential to prevent and protect against these sand hazards.
As the key initiator and participant in both BRI and SRI, China suffers from a great deal of desertification. Until now, the total area of desertification-affected land is approximately 2.64 million km2 in China, covering 28% of the national territorial area and directly affecting nearly 400 million people (Zhang and Huisingh, 2018). Due to desertification, desert areas are expanding at the rate of 210000 ha every year, giving rise to the destruction of natural ecosystems, biodiversity loss, and soil nutrient depletion, as well as damage to infrastructure facilities including traffic lines. In response, a great deal of effort has been made to develop techniques and measures which can stabilize and control mobile dunes to protect roads, railways, and highways in the desert and desertification-affected arid and semi-arid areas in north China. For example, over the past several decades, the Chinese government has initiated many massive eco-engineering projects, including “Three North Shelter Forest System”, “Beijing-Tianjin Sand Source Control Project”, and “Grain for Green Project”, to combat the desertification and reduce its impact by implementing various measures and techniques.
Through a literature survey, this paper reviews the types and features of these techniques and measures regarding how they were used from the 1950s to 2010s in different areas and in different traffic lines. This is followed by a discussion of their successes and failures in preventing sandstorm disaster impacts on the traffic line construction.

2 Aeolian processes and their impacts on traffic lines

Shifting sands or aeolian sands, i.e. sands that move with the winds, are one of the major contributors to desertification in China (Ci and Yang, 2010). Their occurrence is largely determined by aeolian processes which include wind erosion, wind transportation and wind deposition. Wind erosion refers to a process of abrasion and deflation by wind-blown sands (Wu, 1987). Wind transportation is sand movement through suspension, saltation, and creep (i.e., rolling along a surface). Wind deposition means the accumulation of wind-borne sand particles caused by decreases in wind speed. These aeolian processes, especially wind erosion and wind deposition, may bring about hazards or risks to the traffic infrastructures from wind-blown sands, the extent of which depends on wind strength, particle size, and the amount of incoming wind-blown sands (Pimentel and Kounang, 1998). Reducing the effects of these two processes is the key to controlling shifting sand-related hazards. From the perspective of the conditions under which they form, wind is the driving force which acts on shifting sands, either for wind erosion or wind deposition. According to this characteristic, it is necessary to control wind speeds or stabilize the sand surface to prevent sand storms. However, any change of wind speeds will lead to the mutual transformation of wind erosion and wind deposition. Furthermore, it is very difficult to control wind speeds with practical engineering. At present, the main method for preventing sand storms is stabilizing the shifting sand surfaces.
When traffic lines (highways and railways) are built in the regions affected by shifting sands, the road shoulders, roadside slopes, and railway embankments are subject to wind erosion and deposition around the built obstacles. These effects can threaten the service life of the traffic infrastructure and subsequently increase its maintenance costs, even leading to disastrous events, such as train derailment (An et al., 2014). In addition, the erosion by wind-blown sands with high salt concentrations can result in rail corrosion. Therefore, special attention should be paid to potential sand abrasion and corrosion in the design of traffic infrastructures which will be exposed to wind-blown sands.
There are two forms of wind deposition effects on the traffic infrastructure according the wind strength:
(1) Wind-carried sands trapped around the traffic lines: The construction of railways and highways will cause a drop in wind speed, which decreases the sand-carrying capacity of the winds and their ability to transport airborne sands, thereby resulting in sands being deposited on the downwind side of the built obstacles. Traffic lines may become buried eventually with the accumulation of sands in their periphery.
(2) Sand dune movements: Under strong wind conditions, sands are moved from the windward slope and deposited on the leeward slope of sand dunes, resulting in the traffic lines being completely buried by sand dune movement or encroachment.
For both highways and railways, the protective measures against drifting sand damage are basically the same. However, compared with highways, rail embankments, ditches and rails per se are more likely to sustain damage due to accumulation of wind-blown sands. Thus, much more attention should be paid to the maintenance of rails, sleepers, and other railway components.

3 Sand fixing measures

Sand prevention and fixing systems in the arid and semi-arid areas in China are usually designed based on the idea of “sand-arresting, sand-blocking, sand-deviating, and sand-delivering” (Yang et al., 2010). There are three types of measures (techniques) used to fix shifting sands in China, including mechanical, chemical, and biological measures (Wang and Chen, 1997; Sun et al., 2002).

3.1 Mechanical measures

Mechanical measures, also known as engineering measures, refer to the technology that builds barriers on sand dunes or covers the sand dune surfaces with materials such as plant tissues (wheat straw, sorghum stalks, rice straw, reed, twigs and branches of trees or shrubs), soil (clay), rocks (pebbles), or chemicals (petroleum products). These measures have proven to be successful in fixing shifting sand dunes (Eldridge and Kinnell, 1997; Wang et al., 2020). They are mostly used in areas with an extremely arid climate and strong winds, where biological measures are not suitable because of water shortage or damage from the sand flows. For example, the use of straw checkerboards can substantially improve the soil structure and stability (Eldridge and Kinnell, 1997; Li et al., 2006b; Wang et al., 2020). However, they are temporary and effective only for a couple of years. To ensure their success, mechanical measures are usually complemented with other measures, especially biological measures.
As early as before the founding of the People’s Republic of China, mechanical measures such as erecting sand-retaining wind walls or sand burying with soil and mud were used to prevent and control sand damage. However, the research on mechanical measures really began after experts from the former Soviet Union put forward the idea of straw checkerboard barriers to fix sand and control sand storms in Shapotou in Ningxia Hui Autonomous Region (Chang et al., 2006). Before the 1950s, plants grown in sand dunes often died as a result of root exposure to wind erosion without the protection of sand arrestors or sand fences (Liu and Huang, 2000). From the 1950s on, many studies have focused on the appropriate sizes and shapes of mechanical measures in different areas. In the 1970s, with the development of materials science, cost-effectiveness analyses and the assessments of various materials for mechanical measures were conducted.
3.1.1 Sand fixation by fences
Fixing the shifting sand dunes and stabilizing the sand dune surfaces often make use of sand fences, shelter belts or windbreaks, which are usually composed of trees and bushes that are adaptable to the local habitats. Sand-arresting fences can be divided into high and low types, which are usually made of plant tissues (Chang et al., 2018). The optimal height of high sand fences is about 50 cm above the ground for typical sand-moving wind speeds, while low fences are generally 20-30 cm above the ground. Both types of fences are secured to the depth of 10-20 cm below the ground and arranged across the path of prevailing winds (Lima et al., 2017). A square or grid pattern, like a checkerboard, is created between two successive fences. Fences made of straw are commonly called straw checkboards. The checkerboard or grid arrangements of fences are also called semi-concealed or half-buried sand barriers. The mechanism of this approach’s effectiveness is that erected checkerboards reduce wind speeds and their erosive force, causing a buildup of air-borne sands (Chang et al., 2018). The spaces within the checkboard become filled with sand deposits. At present, straw checkboards are widely used in protecting highway and railway infrastructures against sand encroachment and wind-blown sand in the Gobi and desert areas in China (You et al., 2011).
The effectiveness of checkerboards depends on their size and placement in the field, and it is also affected by the intensity of the winds. Straw checkerboards are reportedly the most efficient in protecting railways in north Xinjiang as compared with two other measures (striped sand barriers with and without vegetation) (Sun et al., 2004). Observations on the effect of checkerboard size on sand deposition carried out in Mu Us sandy land (Yanchi, Ningxia) and Tenger Desert (Shapotou, Ningxia) showed that the checkerboards of about 1 m × 1 m presented the best sand-fixing effect (Chang et al., 2018; Zhang et al., 2018a). A study in Tarim Desert Highway showed that achieving a better sand-fixing effect can depend on location, with the size of checkboards set as 0.5 m × 0.5 m at the windward and roadside slope, 1 m × 1 m in open and flat sandy lands, and 2 m × 2 m in the leeward side of the dunes (Han et al., 2000).
Additionally, the type of materials used also affects the success of sand fixation. An experiment along Ahe (Alar-Hotan) Desert Highway showed that among the materials used, reed checkerboards worked best. Maintenance of the checkboards is required as they can be destroyed due to wind-blown sands. The lifespan or permanence of the straw checkboards is a factor to take into account in mechanical sand-fixing measures. Depending on the geographical areas and the quality of the materials used, wheat straw checkboards were reported to work effectively for around four years, and completely decay in seven years in Tenger Desert (Shapotou, Ningxia). Nowadays, the lifespan of the straw checkerboards can be predicted by the published formulas combined with local environmental conditions (Xie et al., 2014).
Within the straw checkerboard, some drought-resistant trees or bushes are planted to reduce soil erosion, enrich the soil, improve the microclimate, and further enhance the effects of sand-binding. Litter from the planted trees and/or bushes provides a mulching effect for the sand surface, which reduces soil evaporation and increases soil water retention. Leguminous plants that can fix atmospheric nitrogen in the soil are often selected to restore the soil fertility. This system has been widely used to control drifting sands and sand erosion throughout north China over the past six decades. However, due to water scarcity and low precipitation levels, the transpiration consumption of the plants has led to a decline in the underground water table and, subsequently, vegetative degradation and a reduced sand-fixing effect.
3.1.2 Sand blocking measures
Sand blocking measures include sand-retaining walls, sand-intercepting ditches, and sand-stopping fences. The sand retaining walls that are plank-type in structure are usually made of clay or sandy gravel and have remarkable sand-blocking effects. Nevertheless, their installation and maintenance are time-consuming and laborious, and reconstruction is needed after three to five years by using film built-in Kraft paper bags or anti-aging non-woven geotextile bags that are filled with sand (Chen, 2004). The merits of this type of construction are that the sand blocking materials used are available locally and that the sand-retaining walls have the flexibility of being raised if they become buried by the shifting sands. Recently, a new type of windproof sand retaining wall, i.e. hollow PVC boxes with holes in the walls for sand filling, have been developed (Wang et al., 2014). Apart from low cost and high availability, this new type of sand retaining wall can be reused, and it stores water available for plant growth even though it is buried by the sands.
The sand intercepting ditch is usually a trench dug in the upwind section along traffic lines. Winds are reduced when entering the ditch and thus the airborne sands deposit at the bottom of the ditch. This measure is not widely used but is limited to the artery traffic lines where sand damage is not too severe. This method will become invalid or ineffective whenever the intercepted sands completely fill the ditches. Therefore, this measure is usually used together with other measures, such as sand-retaining banks, constituting a two-pronged protection system.
The sand-stopping fence, also known as an upright sand-fence, is one of the most widely used mechanical methods to fix sand dunes. The fences are weaved from plant twigs, or made of polyamide, nylon or polyethylene meshes. The mesh size or porosity is designed or regulated depending on the degree of wind slowing that is needed. The fence is generally the first line of defense against sand encroachment in a multi-faceted sand fixing system, and is also the major component of the “sand-blocking in the faraway and sand-fixing in the vicinity” system. The sand-stopping fence works through two steps: 1) altering the structure and turbulence of the air flow field, and 2) slowing down wind speeds in the leeward side of the fences and thereby reducing the sand carrying capacity of the winds, which subsequently affects the particle size distribution of air-borne sands along the leeward side. Some studies have examined the materials used for sand-stopping fences that are applicable to different areas with different degrees of sand damage and resolved the problem of the fences being buried by sands if they are not pulled up in a timely manner (Xie et al., 2014).
In general, sand fences are made from reeds and nylon mesh. An experiment conducted in the Tarim Desert Highway showed no significant difference in the sand-stopping effects between the fences made from reeds and nylon nets (Xu et al., 1998). In the Kubq Desert in Inner Mongolia, fences made of plant fiber nets presented better sand-stopping effects than those made from other materials (Wang et al., 2017). The Qinghai-Tibet Railway poses unusual challenges due to the unique physical and geographical conditions with its high altitude, strong ultraviolet radiation, and strong wind. In addition, plant materials for fences are not always readily available. In such cases, concrete blocks, stones, nylon and polyethylene meshes are generally used to make the sand-stopping fences. In recent years, a new type of upright sand fence made from high density polyethylene has been developed. It possesses high stability, wind erosion-resistance, and strong anti-aging performance under harsh natural environments, e.g. that of the Qinghai-Tibet Railway. A couple of solutions are put forward to address the sand-burying issue of the fences, e.g. raising the fence height by extending the connecting rods. There is a sand-stopping fence design that can move upward with wind speed controlled by a lifting device. However, these methods are currently limited in actual application due to their high cost or flaws in the existing designs, which deserve further study.

3.2 Chemical measures

In addition to mechanical methods, chemical sand fixation methods are also adopted as important measures for sand stabilization. Chemical sand fixation methods refer to chemical cementing agents that are sprayed on the surface of moving sand dunes to form a consolidated layer, which can prevent blowing with the wind, maintain moisture and improve the sandy soil properties (Department of Science and Technology of Gansu Province, 2001). These methods are mainly used for sand stabilization at the side slope and zero section along traffic lines. In addition, they should be considered to not only stabilize sands but also to improve the sand microenvironment for plant growth (Tie et al., 2013). However, as one of the important measures in the sand-fixing and prevention system, chemical sand-fixing methods still need further in-depth study in China and may have the potential for much more rapid progress in the future.
The current research on chemical sand-fixing measures focuses mainly on the preparation and application of the chemical materials. According to chemical composition, the chemical sand-fixing materials can be grouped into three categories: inorganic chemicals, organic chemicals and organic-inorganic composites. Inorganic chemicals are further classified into cement, waterglass (sodium silicate) and gypsum. Waterglass is a cheap non-toxic sand fixation material that has been studied for nearly a century, and is regarded by some researchers as the most important and promising inorganic chemical for sand-fixation (Lai et al., 2017). Organic chemicals for sand-fixing include synthetic polymers, petroleum products, lignin and waste plastics. Nowadays, asphalt emulsions in petroleum products are the most widely used in chemical sand fixation. However, when asphalt emulsion is used alone, the permeability is greatly weakened due to the formation of a thin consolidation layer, which retards the penetration of precipitation water into the soil and is not conducive to plant growth (Pei et al., 1983). Furthermore, this thin layer of consolidation is low in strength and stability. Organic-inorganic composites are emerging as promising materials for sand fixation, and have the advantages of increasing mechanical strength and water-holding capacity when compared to their individual components.
As compared with mechanical measures, chemical sand fixation methods are not widely used in the current sand prevention systems because of their high cost and the lack of required equipment (Zang et al., 2015). However, with their advantages of a short construction period and improvement of the growing conditions for plant recruitment, chemical methods cannot be ignored in the sand prevention systems. Chemical agents suitable for sand-fixing under strong winds have been tested in the Lanxin line (Lanzhou-Xinjiang railway). Some fragments generated by the pyrolysis of sand-fixing chemicals under a strong ultraviolet radiation environment, like in the Qinghai-Tibet Plateau, may scatter in the grassland, which not only pollutes the environment, but also can be accidentally eaten by animals causing their death (Tie et al., 2013). Therefore, such materials are prohibited from use in sand-fixation along the Qinghai-Tibet railway. Under any circumstances, the degradability, toxicity and pollution potential of the sand-fixing chemicals must be assessed and considered before their application. Any damage and pollution to the environment should be avoided. Ultraviolet resistance should be taken into account when selecting sand-fixing chemicals for use in strong UV ray environments. The continuing development and exploration of efficient and safe sand-fixing chemicals is still a worthy research issue.

3.3 Biological measures

Biological measures refer to the methods that stabilize mobile sand dunes, prevent sand damage, and ultimately improve the sand environment and increase land productivity by planting trees, shrubs, and grasses to restore natural vegetation (Department of Science and Technology of Gansu Province, 2001). In 1978, the Chinese Government initiated the “Three-North Shelter Forest Program” (1978-2050), also known as the Green Wall of China, to increase vegetation cover in the north, the northeast and the northwest (the “three norths”) of China. Despite the increase of vegetation cover, desertification still remains one of the serious environmental problems in the “three norths” (Cao, 2008). For example, discrete patches of withering and dead plants on a 1200 km long shelterbelt in the Hexi Corridor occurred due to droughts and/or declining groundwater levels. About 20000 ha of planted forests (87000 ha at the beginning) had been lost to mortality by 2000 in Minqin County (Shi, 2004). In 2010, large-scale tree mortality events occurred in the planted poplar forests in Horqin sandy land. In most of the arid and semi-arid areas, shortages or decreases in the water supply from precipitation and groundwater due to climate change and human activities strongly constrain the growth and survival of planted trees, which eventually may aggravate the drought-induced desertification. In general, bare sand dunes have to be mechanically stabilized prior to the establishment and growth of plants (Kang et al., 2017).
The selection of plant species for biological sand-fixation depends on climatic and ecological conditions, as well as their ability to adapt to these conditions. Failure to select the right species will not only lead to afforestation failure, and a waste of labor, material, and money, but also to the loss of land productivity due to poor growth (Heshmati, 2011). Hence, the selection of appropriate species is the top priority for successful artificial afforestation. Indigenous plants are preferred because they are well adapted to local environmental conditions and can withstand variations in the harsh local climate, such as droughts, heat and strong winds. They require less water, which is typically the most limiting factor for plant growth in semi-arid and arid areas. In addition, in order to achieve high sand-fixation effectiveness, the density of planted trees and mixture of various plant species (e.g. combination of trees, shrubs and grasses) should be given serious consideration (Di et al., 2018). Shrubs such as Caragana korshinskii, Hedysarum scoparium, Calligonum mongolicum and herbaceous plants such as Agriophyllum squarrosum, Artemisia sieversiana, Artemisia ordosica are usually used as the main sand-fixation plants along both the Baolan line (Baotou-Lanzhou railway) and Taizhongyin line (Taiyuan-Zhongwei-Yinchuan railway), where mobile sand dunes are usually distributed along with low water availability. Along the Lanxin line, where the sand surface is relatively stable, sand-fixing vegetation was established with irrigation from surface water and groundwater. Similarly, for the Tarim Desert Highway, where surface water is very scarce, groundwater is used for the growth of sand-fixing plants. Therefore, to make shelter belts in these two traffic lines, drought-tolerant trees such as Haloxylon ammodendr, Tamarix chinensis, and Elaeagnus angustifolia were selected.
In the semi-arid and arid areas, where water supply is the limiting factor for plant growth, planting trees to protect the traffic lines against sand encroachment should consider the availability of water and its sustainability, which will affect the success and effectiveness of the biological sand-fixation measures. Apart from the choice of plant species which are adaptable to local conditions (e.g. drought-resistance), much attention should be paid to a water-saving irrigation system if needed, e.g. adoption of a drip irrigation system. To overcome surface water shortages in the arid and semi-arid ecosystems, lower-quality water, such as saline groundwater, is widely used for irrigation. For example, saline groundwater was selected for drip irrigation along the Tarim Desert Highway shelterbelt. It is reported that saline water may be beneficial for soil nutrient accumulation (Zhang et al., 2016). Moreover, among the three salt- and drought-tolerant plant species (Calligonum aborescens, Tamarix ramosissima, and Haloxylon ammodendron) that were used to stabilize the shifting sands in this highway, C. aborescens performed the best under the same salinity conditions (Zhang et al., 2016). For the areas with low availability of surface water and groundwater, like the Baolan line located on the southeastern edge of the Tengger Desert, which was China’s first railway to pass through the deserts, the planting of sand-fixing plants without irrigation was carried out as early as 1956. This strategy has proven to be successful over the intervening 60 years in protecting the railway against sand dunes and further improving the local eco-environment. In addition, with the evolution of the ecosystem, planted or artificial vegetation has gradually been replaced by natural vegetation with a complex community structure, composition, and function (Li et al., 2004).
Aerial seeding is one of the rapid and effective options for restoring vegetation on a vast area of sand dunes or desertified lands. The success of aerial seeding depends on the seeding timing, the amount of seeds, and the selection of plant species (Department of Science and Technology of Gansu Province, 2001). Aerial seeding can provide the quick restoration of vegetation and enhance the succession and stability of the plant community (Deng et al., 2020).
Biological soil crusts have become a research hotspot in the 21st century. They are complex organic integrations of cyanobacteria, microalgae, mosses, lichens, fungi, and other organisms, embedded in a polysaccharidic matrix, which are encrusted with surface soil fine particles due to the exuded mucilaginous material (Li et al., 2015; Deng et al., 2020). Biological soil crusts are recently regarded as a promising biotechnological measure for sand stabilization. It usually requires more than five years to form a thin layer of the crust. The microbes can be extracted from algae and mosses, cultivated in the lab and sprayed on the sand dune surface to help with the rapid formation of a layer of crust. This thin layer of crust plays an important role in binding loose sand and improving the soil. However, it is fragile and easily damaged by disturbances such as animal trampling and a long time is required for recovery once destroyed. In Shapotou, biological soil crusts represent a key component in accelerating desertification reversal (Li et al., 2006a).
As a whole, biological measures have played a very important role in sand-fixing and vegetation restoration in sand dunes and areas prone to desertification in the “three norths” of China, where many ecological and sand-prevention projects have been implemented to date, since the founding of the People’s Republic of China.
During the implementation of biological measures for sand-fixation, much attention should be paid to the density of planting to avoid competition between seedlings for water and nutrients. The ideal density largely depends on the availability of soil nutrients and soil moisture, both of which are limiting factors for plant survival and growth in arid and semi-arid areas. In addition, planting density choices should fully take into account the slowing and suppression of wind erosion. Before 1964, plants were grown on both sides of the Baolan line, but the water supply did not meet the water demand for plant growth due to the high density of planting, and therefore some plants grew poorly or even died due to water shortage or drought. Later, a nine-year experiment on a multiple-row shrub shelterbelt was carried out there, and found that the shelterbelt composed of two rows of Artemisia ordosica, two rows of Hedysarum scoparium, and two rows of Caragana korshinskii (with 1 m spacing between two neighboring rows) presented higher effectiveness in sand-fixation and vegetation restoration. If the water availability is low, the spacing along and between planting lines (rows) should be wider. In effect, the position and degree of sand encroachment should be considered in the choice of plant species for the shelterbelt arrangement. For example, along the Yumen section of the Lanzhou-Xinjiang railway, three types of shelterbelt configuration were adopted: simple, secondary, and primary shelterbelts with different compositions or combinations of plant species.
Compared with mechanical and chemical measures, the cost of biological measures is 1-3 times higher, but the latter tend to present much better sand fixation performance and longer duration than the former two types of measures (Gong et al., 2001). In addition, only through the biological measures might sand damage be cured or amended fundamentally and permanently. For the movable sand dunes, where the surface is unstable with severe wind-blown damage, sand dune stabilization by the chemical and mechanical measures is generally carried out before planting to create the proper microenvironmental conditions that are suitable for the survival and growth of the introduced plants. For example, at the Meihuajing site of the Taizhongyin line, where high sand dunes have extensive wind-blown sand damage and plants are difficult to grow, the mechanical measures were taken before adopting the biological measures, thus ensuring the success of biological measures (Liu, 2013). At present, in Shapotou, the surface of sand dunes has been fully stabilized for over 60 years by taking the mechanical measures first, and subsequently introducing the biological measures. A combination of chemical and biological measures was taken for sand-fixation in the Qaidam Basin, where the Qinghai-Tibet railway passes through, an area where altitudes are high and the low vegetation cover has a simple community structure composed of few species dominated by shrubs (Tie et al., 2013). For example, grass seeds were sown by mixing with low-cost and environment-friendly gypsum to reduce the effects of strong sunlight on the internal temperatures of sand layer and this approach achieved better sand-fixing effects (Ma and Tie, 2015).
There are two limitations or weakness of biological measures, however. First, the biological methods may not reach the expected sand-fixation effectiveness in a short time, especially at the early stages, because it takes time for restoration of vegetation and assembly of the plant community. Second, the preliminary investigation of site conditions and field testing of the selected plants are necessary before the implementation of any biological measures in the target areas.
Whether one measure or a combination of different measures should be adopted in a given region depends on the magnitude of sand storms and the availability of materials used. Sand dunes, especially along the fringe of sandy desert encroachment, seriously harm or threaten farmland, villages, irrigation canals, reservoirs, transportation (highway, railway), mining sites, etc. In these areas, mechanical measures are suitable and preferable to biological ones as emergent measures to fight against the movement of sand dunes. In some extremely arid areas which are subject to wind and sand movement, plants can barely survive and grow in order to prevent sand dune encroachment, and so mechanical measures must be taken. When it is desirable to plant trees, shrubs or grasses on the sand dunes in some areas, mechanical measures should be taken before planting. Otherwise the seeds or seedlings of the plants will be exposed to wind or buried by blown sands even if the soil moisture content is available and other natural factors are suitable for the plants. Mechanical measures, under these conditions, can prevent sand dunes from moving and guarantee the survival of these seedlings of the sand-binding plant species.

4 Cases along the traffic lines

In China, there are eight major deserts (Taklamakan and Kumtag Deserts in the Tarim Basin, Gurbantunggut Desert in the Junggar Basin, Qaidam Desert in the Qaidam Basin, Badain Jaran, Tengger and Ulan Buh Deserts in the Alxa Plateau, and Kubq Desert in the Ordos Plateau), and four sandy lands (Mu Us, Otindag, Horqin, and Hulun Buir sandy lands in the Mongolian Plateau). They are mainly distributed in arid, semi-arid and dry sub-humid areas in northwest, north and northeast of China (Fig. 1). The desert and sandy land areas in China were respectively 261.16 million ha and 172.12 million ha by 2014, and respectively accounted for about 27.2% and 17.9% of the total land area (State Forestry Bureau, 2015). Desert and sandy lands are ecologically vulnerable and prone to wind erosion and desertification. Since the foundation of the P. R. China in 1949, especially since the reform and opening-up starting from 1978, several railways and highways have been constructed in the arid and semi-arid areas of China, noticeably with implementation of the strategic plan of the Great Western Development (2001-2050). Here we briefly introduce some examples which show how sand fixing measures and techniques are being used to protect some of these traffic lines against shifting sand damage (Table 1; Fig. 2) (Hu et al., 2002; Han et al., 2003; Zhang et al., 2010; Zhang et al., 2011; Zhang et al., 2019).
Fig. 1 Distribution of Chinese deserts and sandy lands

Note: Data from the National Earth System Science Data Center, National Science & Technology Infrastructure of China, http://www.geodata.cn.

Table 1 Basic information on sand fixing measures taken along three traffic lines (Baotou-Lanzhou railway, Tarim Desert highway, and Qinghai-Tibet railway)
Basic information Sand barriers and sand-arresting technique
Traffic lines Nearby sand source & description Climate & sand
damage type		 Mechanical measures Biological measures Chemical measures
Baotou-Lanzhou
railway (Shapotou)		 Tengger Desert
990 km, completed in 1958		 Temperate continental desert climate
Soil erosion		 1. Straw checkerboards
(1×1 m) (Zhang et al., 2011)
2. Sand fence (1.2 m tall and 30% porosity)		 An unirrigated
vegetation belt and an irrigated vegetation zone (Zhang et al., 2019)		 ——
Tarim Desert highway Taklamakan Desert
566 km, completed in 1995		 Extreme drought
Wind erosion		 1. Reed checkerboards
2. Nylon sand fences
with narrow tripped
nets (He et al., 2014)		 1. Unirrigated
afforestation
2. Drip irrigation system
3. Saline water irriga
tion (Han et al., 2003)		 Sand-fixing materials:
LVA, LVP, WBS and STB (Han et al., 2007)
Qinghai-Tibet railway Tibetan Plateau
1956 km, completed in 2006		 Plateau continental
climate
Soil erosion (Golmud, Lhasa), sand burial
(Xining-Golmud)		 1. Rocky checkerboards
2. Sand-blocking fences
3. Sand-deviating boards
4. Plant-mechanical
comprehensive sand
barriers (Zhang et al.,
2010)		 Almost none
(because of alpine
environment)		 DST and organosiloxane
prepolymer (Zhang et al., 2019)

Note: LVA, a polyvinyl alcohol emulsion; LVP, a polyvinyl acetate emulsion; WBS, a mixture of water glass and calcium chloride; STB, a mixture of water glass and urea; DST, an original composite chemical binder.

Fig. 2 Railways (a) and highways (b) in the desert and desertification-affected arid and semi-arid areas of China

Note: Data from the National Earth System Science Data Center, National Science & Technology Infrastructure of China, http://www.geodata.cn.

The Baotou-Lanzhou Railway (Baolan line) is a 995 km railway that connects the cities of Baotou in Inner Mongolia to Lanzhou in Gansu Province. It was completed in 1958, passing through the Tengger Desert six times for 140 km. At the early stage of railway operation, encroaching sand dunes or sandstorms frequently buried the rails or tracks, disrupted the train services and sometimes caused minor accidents. Straw barriers, 1-square-meter straw grids which resemble checkerboards, were used to prevent the railway from being buried by shifting sand dunes. The rice or wheat straw checkerboards, usually spaced 1 m apart, have proven to be the most convenient, environmentally-friendly and cost- effective way of stopping sand dune encroachment. The straw is erected from around 10 cm below ground to 20-30 cm above ground. Erecting the straw checkboards is labor-intensive and usually done by two persons working together, one laying the straw on the sand surfaces and the other pressing the straw into the sand with a spade. With stabilization of the sand dune surface, a biological crust was formed over time and subsequently played a critical role in improving soil nutrients. Along with the straw checkerboards, grass belts, shrubs, and wind breaks were also constructed to prevent the railway from being buried by moving sand dunes. At the early stage of planting, water from the Yellow River was pumped to irrigate the plants. Due to the straw checkerboard, the wind speed at a height of 0.5 m has been reduced by 20%-40%. As a result, the intensity of sand flow was decreased by almost 100% (Li et al., 2004). By 1990, the railway became completely free from sand erosion, and the railway has now been operating smoothly for more than 60 years. However, the sand fixation efforts have not stopped with the checkerboard. Later on, plants that are well-adapted to arid environments were selected and planted in the one square meter areas of the checkerboard. These shrub plant species include Caragana korshinskii (Korshinsk peashrub), Hedysarum scoparium (slender branch sweetvetch), Artemisia ordosica (Ordos wormwood), Atraphaxis bracteates, and Calligonum mongolicum. As early as 1956, sand-binding vegetation was planted as a “vegetation protection system” to stabilize the sand dunes and prevent their encroachment in the Shapotou region at the southeastern edge of the Tengger Desert, northern China (Li et al., 2004). Using the successful experiences obtained in Shapotou area as a model, the same methods, especially the “straw checkerboard” technique, have been popularized in other places: the Muus Desert (Erdos), Horqin sandy land (the largest sandy land in China), and even in some Middle Eastern and African countries (Li et al., 2004).
The Tarim Desert Highway, also called Taklamakan Desert Highway or Cross-Desert Highway (CDH), is an asphalted road of 566 km long completed in 1995. It passes across the Taklimakan Desert, known as the uninhabited “sea of death”, and links the cities of Luntai and Minfeng on the northern and southern edges of the Tarim Basin in the Xinjiang Autonomous Region, China. The improvement of road infrastructure facilitates the exploitation of rich natural resources in desert areas and has implications for social economy development. About four-fifths of that road is frequently buried or affected by shifting sands. Rows of vegetation were artificially planted on both sides of the road to prevent it from being buried by the encroaching sand dunes. The plant species selected mainly include Tamarix chinensis (Chinese tamarisk or saltcedar), Calligonum mongolicum, and Haloxylon ammodendron (Saxaul, Sacsaoul or Saksaul), which are native drought- and salt-tolerant trees and shrubs suitable to the harsh local habitats. These plant species were used to establish windbreaks or shelterbelts (with 2 m spacing between neighboring rows and 1 m spacing between individual trees within the rows) on both sides of the Tarim Desert Highway in 2003, which are known as the Tarim Desert Highway Shelterbelts (Zhang et al., 2016). The shelterbelt plants are watered by drip irrigation systems using groundwater with high salinity of 2.8-29.9 g L-1 (Han et al., 2012). To date, nearly four-fifths of the highway has been protected against shifting sand dune encroachment by the tree shelterbelts which are around 80 m wide. These shelterbelts have proven to be a success because they have stabilized the shifting sand dunes on both sides of the highway and, to some extent, they altered the microclimate. Other tree species, such as Populus euphratica and Elaeagnus angustifolia, and grasses are also being tested through field experiments (Zhang et al., 2009).
The Qinghai-Tibet railway (QTR), is the longest high-altitude railway in the world. It spans 1956 km from Xining to Lhasa, of which the Xining-Golmud section (814 km) and the Golmud-Lhasa section (1142 km) went into operation in 1984 and 2006, respectively. With about half of its length is at more than 4000 m above sea level, and the railway runs through some mountains, Gobi Desert and permafrost. In addition, about 443 km of the railway is frequently threatened by or suffers from wind-blown sands and wind erosion due to desertification. Climate change and overgrazing are the main causes of desertification in the Qinghai-Tibet plateau (Feng et al., 2006; Yang et al., 2014). Since the opening of QTR, one of key issues has been preventing the negative influences from sand hazards. Due to its special geographical location, sand-fixing measures in the Tibetan Plateau are different from those in other regions. The plant materials are not readily available, such as wheat straw and reeds that are difficult to grow on the plateau with an altitude of 3000-5000 m. Therefore, stone checkerboards were used on the plateau to fix the sand dunes, but the stone checkerboards are expensive and difficult to construct (Xie et al., 2014). In this case, new materials such as high density poly-ethylene (HDPE) were used in sand stabilization. As compared with straw checkerboards which readily decay, HDPE sand fences provide a longer period of protection against sand damage, and help to improve the microenvironment over time due to increases in biodiversity and nutrient accumulation in the spaces between the fences (Wang et al., 2014). To date, there are only a few studies on biological sand-fixing measures for the cold areas at high altitudes. However, much attention has focused on the study of sand-fixing along the QTR, which has implications for narrowing the knowledge gap about sand-fixing in the cold areas with high elevations. In terms of biological measures in the plateau, where the soils are nutrient-deficient and their water-holding capacity is low, native plants that adapt well to local environments can be selected and planted with proper portions of plant-growing substrate. This strategy has benefitted by adopting such new methods as the seed-nutrient-soil sacks, the thick-layer matrix spray-adsorption method and three-dimensional net technology. It is reported that planting trees together with shrubs or grasses presents higher effectiveness and efficiency of sand encroachment control and vegetation restoration in the sandy areas along the Qinghai-Tibet railway (Feng et al., 2005). Along the QTR, mechanical measures were also used in conjunction with the biological measures or chemical measures to prevent sand damage. For example, the plant-mechanical comprehensive sand barrier has been developed as a new type of sand-fixation and vegetation restoration mode for the sand dunes in the cold regions at high altitudes (Guo et al., 2019).

5 Future outlook

Many techniques exist for preventing, avoiding or mitigating the effects of sand dune encroachment on the traffic lines and infrastructure, including some which are environmental-friendly and economically beneficial. Although many have turned out to be successful, there are also some barriers to their implementation, such as their costs, maintenance issues, and the disturbances to microenvironments, landscapes and animal migration, among others.
To date, most of the existing sand-fixing projects have been carried out along the traffic infrastructure, with less attention focusing on infrastructure components such as power stations, power lines, and oil and gas pipelines. It is well known that sand damage to basic infrastructure mainly includes sand burial and wind erosion. The sand-fixing measures taken for the basic infrastructure do not differ from those for the traffic infrastructure since the types of sand damage are almost the same (Yuan, 2016; Tan et al., 2017). Proper mechanical and/or chemical measures are implemented first to stabilize the sand dune surface for a short-term effect, followed by biological measures such as the establishment of vegetation belts for a long-term effect. When the mobile sand dunes are fixed, the damage of wind erosion can be prevented due to the lack of a sand source.
Using advanced techniques and methods, the sand damage prevention along transport lines mainly focuses on the following aspects: 1) Attaching importance to the biological crust, especially algae and mosses, as biological measures to curb desertification (Hobbs and Cramer, 2008; Zhang et al., 2015; Wu et al., 2018); 2) Conducting in-depth studies on the functional traits (Cao et al., 2011) of xerophyte desert plants including eremophyte and plant-soil interactions (Zhang et al., 2016; Luo et al., 2018; Yang et al., 2019) for selection of sand-fixing plants; 3) Paying attention to the impact of climate change on sand-fixing plants to maintain the long-term effectiveness of biological measures (Li et al., 2018; Chang et al., 2019); 4) Monitoring and predicting road conditions and vegetation dynamics in the sand damage-affected areas by means of remote sensing, GIS and models (Li et al., 2016; Wan et al., 2018); and 5) Monitoring wind-sand flow (wind-blown sands) and moisture conditions for timely optimization of the sand-fixing measures (Cui et al., 2018; Zhang et al., 2018b). These aspects are essential for preventing and controlling the impacts of shifting sands on the construction of traffic facilities and infrastructures under the BRI.

References

Publishing order | Descend order by publishing year | Descend order by cited within
[1]
An Z S, Zhang K C, Qu J J, et al. 2014. Sand hazard characteristics and genetic analysis along the Qinghai-Tibet railway. Research of Soil and Water Conservation, 21(2):285-289. (in Chinese)

[2]
Cao C, Jiang S, Ying Z, et al. 2011. Spatial variability of soil nutrients and microbiological properties after the establishment of leguminous shrub Caragana microphylla Lam. plantation on sand dune in the Horqin Sandy Land of Northeast China. Ecological Engineering, 37(10), 1467-1475.

DOI

[3]
Cao S X. 2008. Why large-scale afforestation efforts in China have failed to solve the desertification problem. Environmental Science and Technology, 42(6):1826-1831.

DOI PMID

[4]
Chang H, Liu T, Wang D W, et al. 2019. Haloxylon ammodendron’s potential distribution under climate change in arid areas of northwest China. Journal of Desert Research, 39(1):110-118. (in Chinese)

[5]
Chang Z F, Liu S Z, Wang Q, et al. 2018. Progress and problems of development research and application of sand barriers. Meteorological & Environmental Research, 9(3):22-27, 33.

[6]
Chang Z F, Zhao M. 2006. Study on desert ecology in Minqin. Lanzhou: Gansu Science and Technology Publishing House. (in Chinese)

[7]
Chen G T. 2004. Technology of sand control. Beijing: Chemical Industry Press. (in Chinese)

[8]
Ci L, Yang X. 2010. Desertification and its control in China. Beijing: Higher Education Press. (in Chinese)

[9]
Cui Y Z, Li X R, Zhao Y, et al. 2018. Introduction of eco-hydrological research and auto-simulating and monitoring system of water balance in desert regions in the northern China. Journal of Desert Research, 38(6):1166-1174. (in Chinese)

[10]
Deng S, Zhang D, Wang G, et al. 2020. Biological soil crust succession in deserts through a 59-year-long case study in China: How induced biological soil crust strategy accelerates desertification reversal from decades to years. Soil Biology and Biochemistry, 141:107665. DOI: 10.1016/j.soilbio.2019.107665.

DOI

[11]
Department of Science and Technology of Gansu Province. 2001. Desertification control and technology. Lanzhou: Gansu People’s Publishing House. (in Chinese)

[12]
Di W J, Zhang Y C, He L, et al. 2018. Selection principles of plant species for wind break and sand fixation. Agriculture and Technology, 38(22):216. (in Chinese)

[13]
Eldridge D J, Kinnell P I A. 1997. Assessment of erosion rates from microphyte-dominated monoliths under rain-impacted flow. Australian Journal of Soil Research, 35:475-489.

[14]
Feng J M, Wang T, Xie C W. 2006. Eco-environmental degradation in the source region of the Yellow River, Northeast Qinghai-Xizang Plateau. Environmental Monitoring & Assessment, 122(1-3):125-143.

DOI PMID

[15]
Feng L L, Jia Z Q, Liu T, et al. 2005. Comparative study on fine roots productivity and turnover rates of several typical sand-fixation plants in Alpine sandy land. Research of Soil and Water Conservation, 25(2):120-130. (in Chinese)

[16]
Gong F H, He X D, Peng X Y, et al. 2001. Comparison of properties and cost of different sand-fixing system along Tarim Desert Highway. Journal of Desert Research, 21(1):45-49. (in Chinese)

[17]
Guo X L, Liu W H, Chen J, el al. 2019. Effect of different vegetation planting patterns in restoration of degraded sandy land in northwest Sichuan. Acta Prataculturae Sinica, 28(6):33-44. (in Chinese)

[18]
Han W, Cao L, Yimit H, et al. 2012. Optimization of the saline groundwater irrigation system along the Tarim Desert Highway Ecological Shelterbelt Project in China. Ecological Engineering, 40:108-112.

DOI

[19]
Han Z W, Chen G T, Hu Y D, et al. 2000. Discussion on problems about construction of sand-controlling systems along desert highway in Tarim Basin, Taklimakan Desert. Journal of Arid Land Resources and Environment, 14(2):35-40.

[20]
Han Z W, Wang T, Sun Q W, et al. 2003. Sand harm in Taklimakan Desert highway and sand control. Acta Geographica Sinica, 58(2):201-208. (in Chinese)

DOI

[21]
Han Z, Wang T, Dong Z, et al. 2007. Chemical stabilization of mobile dunefields along a highway in the Taklimakan Desert of China. Journal of Arid Environments, 68(2):260-270.

DOI

[22]
He Z H, Li S Y, Wang H F, et al. 2014. Comparison of wind prevention and sand blocking effects of 4 types of sand blocking nylon nets in the Central Taklimakan Desert. Arid Zone Research, 31(2):369-374. (in Chinese)

[23]
Heshmati G A. 2011. Biological models for protecting different land use in arid areas China. Journal of Rangeland Science, 1(3):235-246.

[24]
Hobbs R J, Cramer V A. 2008. Restoration ecology: Interventionist approaches for restoring and maintaining ecosystem function in the face of rapid environmental change. Annual Review of Environment and Resources, 33:39-61.

DOI

[25]
Hu C Y, Yang M, Yang C L, et al. 2002. Integrated techniques of sand damage control for the highway of crossing Kubq Desert. Journal of Arid Land Resources and Environment, 16(3):71-77. (in Chinese)

[26]
Kang J, Zhao M, Tan Y, et al. 2017. Sand-fixing characteristics of Carex brunnescens and its application with straw checkerboard technique in restoration of degraded alpine meadows. Journal of Arid Land, 9(5):651-665.

DOI

[27]
Lai J H, Zhang K, Wang W S, et al. 2017. Research advances and prospect in chemical sand-fixing materials. Journal of Desert Research, 37(4):644-658. (in Chinese)

[28]
Li J, Liu Z, He C, et al. 2016. Are the drylands in northern China sustainable? A perspective from ecological footprint dynamics from 1990 to 2010. Science of the Total Environment, 553:223-231.

DOI

[29]
Li L L, Wang D W, Han T. 2018. Spatial-temporal dynamics of vegetation coverage and responding to climate change in Shiyang river basin during 2000-2015. Journal of Desert Research, 38(5):1108-1118. (in Chinese)

[30]
Li S Z, Xiao H L, Cheng G D, et al. 2006a. Mechanical disturbance of microbiotic crusts affects ecohydrological processes in a region of revegetation-fixed sand dunes. Arid Land Research and Management, 20(1):61-77.

DOI

[31]
Li X R, Xiao H L, He M Z, et al. 2006b. Sand barriers of straw checkerboards for habitat restoration in extremely arid desert regions. Ecological Engineering, 28(2):149-157. (in Chinese)

DOI

[32]
Li X R, Zhang Y M, Zhao Y G. 2015. A study of biological soil crusts: Recent development, trend and prospect. Advances in Earth Science, 24(1):11-24.

[33]
Li X, Xiao H, Zhang J, et al. 2004. Long-term ecosystem effects of sand-binding vegetation in the Tengger Desert, northern China. Restoration Ecology, 12:376-390.

DOI

[34]
Lima I A, Araújo A D, Parteli E, et al. 2017. Optimal array of sand fences. Scientific Reports, 7:45148. DOI: 10.1038/srep45148.

DOI PMID

[35]
Liu H. 2013. Study on characteristic of blown—Sand hazards and preventive measurements along Taiyuan-Zhongwei-Yinchuan railway. Diss., Lanzhou Jiaotong University. (in Chinese)

[36]
Liu Y X, Huang Z H. 2000. Vegetal dune stabilization and grassland management. Lanzhou: Gansu Culture Press. (in Chinese)

[37]
Luo Q H, Ning H S, Chen Q M, et al. 2018. Relation between vegetation and soil of Haloxylon ammodendron plantation in the process of sand-fixation. Journal of Desert Research, 38(4):780-790. (in Chinese)

[38]
Ma X F, Tie S N. 2015. Experiment on plant compatibility of gypsum-based sand fixation plant composites in desertification area of Qinghai Lake. Material Review, 29(9):94-99. (in Chinese)

[39]
Pei Z Q, Guo G P, Yang F Z, et al. 1983. The test of sand stabilization by asphalt emulsions. Journal of Desert Research, 3(2):23-29. (in Chinese)

[40]
Pimentel D, Kounang N. 1998. Ecology of soil erosion in ecosystems. Ecosystems, 1:416-426.

DOI

[41]
Shi Y C. 2004. Extricate ourselves from the dilemma of desertification control and return of reclaimed farmland (to afforested area). Acta Agrestia Sinica, 12(2):83-86. (in Chinese)

[42]
State Forestry Bureau of China. 2015. China’s desertification and sandy status bulletin. (in Chinese)

[43]
Sun Q W, Wang T, Han Z W, et al. 2004. Blown sand harm along north Xinjiang railway and its control. Journal of Desert Research, 24(2):182-186. (in Chinese)

[44]
Sun S P, Zhu L H, Zeng C, et al. 2002. Analysis on the feasibility of construction of the biological sand-control systems along the roads of the Tazhong Desert oil field. Arid Zone Research, 19(4):21-24. (in Chinese)

[45]
Tan L H, Ma L, An Z S, et al. 2017. Present situation, causes and control measures of aeolian sand disaster in photovoltaic power generation base in Gonghe Basin, Qinghai Province. Bulletin of Soil and Water Conservation, 37(3):182-187. (in Chinese)

[46]
Tie S N, Jiang X, Wang C A. 2013. Progress in research on chemical sand-fixing materials for desertification control. Science & Technology Review, 31(5):106-111. (in Chinese)

[47]
Tie S N, Jiang X, Wang C A. 2013. Research progress on chemical sand fixation materials. Material Review. 27(5):71-75. (in Chinese)

[48]
Wan W, Yan C Z, Xian S C, et al. 2018. Process, spatial pattern and driving mechanism of the aeolian desertification in the Alxa plateau from 1975 to 2015. Journal of Desert Research, 38(1):17-29. (in Chinese)

[49]
Wang R, Zhou L H, Chen Y, et al. 2017. Wind-blown sand control effect of sand barriers used in the Kubq Desert. Arid Zone Research, 34(2):330-336. (in Chinese)

[50]
Wang T, Qu J J, Niu Q H. 2020. Comparative study of the shelter efficacy of straw checkerboard barriers and rocky checkerboard barriers in a wind tunnel. Aeolian Research, 43:1-11.

[51]
Wang X M, Chen G T. 1997. Efficiencies and reason width for the mechanical sand-prevention system along the Tarim Desert Highway. Journal of Arid Land Resources and Environment, 11(4):28-35. (in Chinese)

[52]
Wang Y M, Liu K, Qu J J, et al. 2014. Effects of sand barriers on vegetation and soil nutrient in sand dunes. Journal of Desert Research, 34(1):42-48. (in Chinese)

DOI

[53]
Wu Y S, Yin R P, Tian X M. 2018. Development characteristic of biological crusts under artificial vegetation in southern Mu Us sandy land. Journal of Desert Research, 38(2):339-344. (in Chinese)

[54]
Wu Z. 1987. Aeolian Geomorphology. Beijing: Science Press. (in Chinese)

[55]
Xie S B, Qu J J, Liu B, et al. 2014. Advances in research on the sand hazards and its controls along the Qinghai-Tibet railway. Journal of Desert Research, 34(1):42-48. (in Chinese)

DOI

[56]
Xu X W, Hu Y K, Pan B R. 1998. Analysis on protection effect of various measures of combating drifting sand on Tarim Desert Highway. Arid Zone Research, 15(1):21-26. (in Chinese)

[57]
Yang K, Wu H, Qin J, et al. 2014. Recent climate changes over the Tibetan Plateau and their impacts on energy and water cycle: A review. Global and Planetary Change, 112:79-91.

DOI

[58]
Yang W, Wang Y, He C, et al. 2019. Soil water content and temperature dynamics under grassland degradation: A multi-depth continuous measurement from the agricultural pastoral ecotone in northwest China. Sustainability, 11(15):4188. DOI: 10.3390/su11154188.

DOI

[59]
Yang Y H, Jiang F Q, Wang X L, et al. 2010. Prevention and management of blown-sand hazards along Qinghai-Tibet railway in Cuona Lake area. Journal of Desert Research, 30(6):1256-1262. (in Chinese)

[60]
You Q G, Zhao F Z, Xue X, et al. 2011. Wind tunnel experiment of the effect of sand prevention measures along Gobi highway. Journal of Desert Research, 31(3):550-557. (in Chinese)

[61]
Yuan F. 2016. Study of the effectiveness and mechanism of wind erosion control of engineering measures of photovoltaic constructing land in northwest sandstorm. Diss., Northwest A&F University. (in Chinese)

[62]
Zang Y X, Gong W, Xie H, et al. 2015. Chemical sand stabilization: A review of material, mechanism, and problems. Environmental Technology Reviews, 4(1):119-132.

DOI

[63]
Zhang D H, Li X R, Zhang F, et al. 2016. Effects of rainfall intensity and intermittency on woody vegetation cover and deep soil moisture in dryland ecosystems. Journal of Hydrology, 543:270-282.

DOI

[64]
Zhang J G, Lei J Q, Wang Y D, et al. 2016. Survival and growth of three afforestation species under high saline drip irrigation in the Taklimakan Desert, China. Ecosphere, 7(5):e01285. DOI: 10.1002/ecs2.1285.

[65]
Zhang J G, Xu X W, Lei J Q, et al. 2009. Research on construction and application of adaptability evaluation indicator system of introduced plants in the hinterland of Taklimakan desert. Journal of Natural Resources, 24(5):849-858. (in Chinese)

DOI

[66]
Zhang J, Xu X, Li S, et al. 2016. Is the Taklimakan Desert highway shelterbelt sustainable to long-term drip irrigation with high saline groundwater? Plos One, 11(10):e0164106. DOI: 10.1371/journal.pone. 0164106.

DOI PMID

[67]
Zhang J, Zhang C, Zhou N, et al. 2011. Spatial pattern of grain-size distribution in surface sediments as a result of variations in the aeolian environment in China’s Shapotou railway protective system. Aeolian Research, 3(3):295-302.

DOI

[68]
Zhang K C, Qu J J, Liao K T, et al. 2010. Damage by wind-blown sand and its control along Qinghai-Tibet railway in China. Aeolian Research, 1(3-4):143-146.

DOI

[69]
Zhang K C, Qu J J, Yu Y P, et al. 2019. Progress of research on wind-blown sand prevention and control of railways in China. Advances in Earth Science, 34(6):573-583. (in Chinese)

[70]
Zhang S, Ding G D, Yu M H, et al. 2018a. Effect of straw checkerboards on wind proofing, sand fixation, and ecological restoration in shifting. International Journal of Environmental Research and Public, (15):1-17.

[71]
Zhang Z S, Dong X J, Xu B X, et al. 2015. Soil respiration sensitivities to water and temperature in a revegetated desert. Journal of Geophysical Research: Biogeosciences, 120(4):773-787.

[72]
Zhang Z S, Li X R, Zhao Y, et al. 2018b. Introduction of eco-hydrological research and auto-simulating and monitoring system of water balance in desert regions in the Northern China. Journal of Desert Research, 38(6):1119-1135. (in Chinese)

[73]
Zhang Z, Huisingh D. 2018. Combating desertification in China: Monitoring, control, management and revegetation. Journal of Cleaner Production, 182:765-775.

DOI

Options
Outlines

/

〈 〉