Search

Recently, sand fences, made of high density polyethylene (HDPE) board, which is resistant against harsh plateau environmental conditions, could possibly be used to control the wind-blown sand along the Qinghai section of the Golmud-Korla Railway. In this paper, wind tunnel simulation was performed on the protective effect of multiple rows of HDPE board sand fences on wind-blown sand. Two parameters have been used to reflect the protective effect of sand fences, that is, windproof efficiency and sand control efficiency, referring to the reduction rates of wind speed at a height of 0.04 m and sand flux in a run of test with the fence compared those in the control run of test without it, respectively. The test results showed that when the porosity was 30%, the single-row sand fence had the best wind proof and sand control efficiency with respective values of 46% and 65.3%. The windproof efficiencies of double-row and triple-row sand fences at 20H were 59% and 62%, respectively. Compared with the windproof efficiency of the single-row sand fence, those of the two-row and three-row fences increased by 13% and 16%, respectively; The maximum sand control efficiency of the double-row and triple-row sand fences were 92.1% and 96.5%, increased by 26.8% and 31.2%, respectively, compared with that of the single-row sand fence. This study indicates that the sand control efficiency after adding one or two rows was not double or triple that of the single-row fence, while the first-row sand fence played a major protective role. Compared with the double-row sand fences, the effect of the third row sand fence in triple-row sand fences is limited, and thus double-row HDPE board sand fences with the porosity of 30% are recommended to control wind-blown sand along the Qinghai section of the Golmud-Korla Railway.

Based on the 3D fluid–solid coupling numerical calculation method, a systematic study was conducted on the bearing characteristics of a perforated sheet-type sand fence at a given penetration rate, opening size, and wind velocity. According to the results of this study, both the displacement and stress of the sand fence experienced an impact stage, a coupling stage, and a stabilization stage under different wind velocities and times. At the initial moment of the impact stage, both the displacement and stress of the sand fence reached their maximum, i.e., the maximum position of the sand fence displacement was at the top of the panel central line, whereas the maximum position of the stress was at the site of the column 4.5 cm away from the column bottom. The duration of the impact stage was 1.5 s and did not change with the opening size or wind velocity. In the coupling stage, the displacement and stress of the sand fence underwent intense fluctuations, and the amplitude of fluctuations decreased with time. The duration of the coupling stage did not change with opening size, but increased with the increase in wind velocity. In the stabilization stage, both the displacement and stress of the sand fence reached a stable state and did not significantly change with time. In each stage, both the displacement and stress of the sand fence are inversely proportional to the opening size and directly proportional to the wind velocity, i.e., the lower the opening size, the higher the wind velocity, and the greater the displacement and stress of the sand fence. However, when the hole diameter drops below 1.03 cm, it is no longer a main influencing factor of sand fence displacement or stress change. For the sand fence in each stage, the panel displacement was higher than the column displacement, whereas the column stress was higher than the panel stress. This paper provides a basis for the design and optimization of sand fence structures, lays the foundation for establishing a mechanics-physics model for the stress distribution of sand fence structures, and presents relatively high research values.

Landforms present in undeveloped beach enclaves located between properties developed with houses and infrastructure are often left to evolve naturally but are influenced by the human structures near them. This field study evaluates how buildings and sand-trapping fences change the direction of wind approach, reduce wind speed, and restrict fetch distances for sediment entrainment, thereby reducing the potential for aeolian transport and development of dunes in enclaves. Field data were gathered in an 80 m long, 44 m deep beach enclave on the ocean shoreline of New Jersey, USA. Comparison of wind characteristics in the enclave with a site unaffected by buildings revealed that offshore winds in the enclave are reduced in strength and altered in direction by landward houses, increasing the relative importance of longshore winds. Vertical arrays of anemometers on the foredune crest, foredune toe and berm crest in the enclave revealed increasing wind speed with distance offshore, with strongest winds on the berm crest. Vertical cylindrical traps on the foredune crest, foredune toe, mid-backshore, berm crest and upper foreshore revealed the greatest rate of sediment transport on the berm crest. Sediment samples from the beach and from traps revealed limited potential for aeolian transport because of coarse grain sizes. Strong oblique onshore winds are common in this region and are normally important for transporting sand to dunes. The length of an enclave and the setback distance on its landward side determine the degree to which sediment delivered by oblique winds contributes to dune growth. The landward edge of the enclave (defined by a sand fence near the dune toe) is sheltered along its entire length from winds blowing at an angle to the shoreline of 25° or less. A foredune set back this distance in an enclave the length of an individual lot (about 20 m) would be sheltered at an angle of 57° or less, reducing the opportunity for dune building by onshore winds. Reduced potential for aeolian transport in enclaves implies that human actions may be required to build dunes artificially to protect buildings and roads from storm overwash.

The inclined inserting-type sand fence is a novel sand retaining wall adopted along the Lanxin High-Speed Railway II in Xinjiang for controlling and blocking sand movement. To verify the effectiveness of the new fence structure for sand prevention, a wind tunnel test was used for flow field test simulation of the sand fence. The results indicate that the inclined inserting-type sand fence was able to deflect the flow of the sand and was able to easily form an upward slant acceleration zone on the leeward side of the sand fence. As shown by the percentage change in sand collection rates on the windward side and the leeward side of the sand fence, the sand flux per unit area at 4 m height in the slant upward direction increased on the leeward side of the inclined inserting-type sand fence. By comparing the flow fields, this site is an acceleration zone, which also reaffirms the correspondence of wind–sand flow fields with the spatial distribution characteristic of the wind-carried sand motion. The field sand collection data indicates that under the effects of the inclined inserting-type sand fence, the sandy air currents passing in front and behind the sand fence not only changed in quality, but the grain composition and particle size also significantly changed, suggesting that the inclined inserting-type sand fence has a sorting and filtering effect on the sandy air currents that passed through. The fence retained coarse particulates on the windward side and fine particulates within the shade of the wind on the leeward side.

A hanging-type sand-retaining wall is a very common sand-blocking fence structure used to prevent sand movement. This type of wall is widely used along the Qinghai–Tibet and Gobi desert railways in Xinjiang, Western China. To analyze the characteristics of wind-sand flow fields under the effect of such a sand fence structure, a wind tunnel test and a field test were carried out. The wind tunnel test showed the zoning characteristics of the flow fields under the effect of the hanging-type sand-retaining wall, and the field test provided the sediment transport data for effective wind-proof interval and the sand resistance data in the front and behind the sand-retaining wall. The consistency of the wind-sand flow fields with the spatial distribution characteristic of wind-carried sand motion was verified by the correspondences of the acceleration zone in the flow field and the negative elevation points of the percentage variations of the sand collection rate. The spatial distribution characteristic of the field sand collection data further showed the spatial structural characteristic of the sandy air currents under the action of the hanging-type sand-retaining wall and the sand resistance characteristic of the sand-retaining wall. This systematic study on the wind-sand flow fields under the control of the hanging-type sand-retaining wall provides a theoretical basis for the rational layout of sand control engineering systems and the efficient utilization of a hanging-type sand-retaining wall.

This study aimed to examine the effect of distance at three levels (5 m, 15 m, and 25 m) of ranges of plots landwards from a sand fence and bush hedge protection margin on the height growth and survival of seedlings of Pinus thunbergii Parl. planted in a coastal sandy environment in Uljin, East Sea area of Korea. The purpose of the study was to investigate height growth and survival with distance from a bush hedge/sand beach boundary of pine seedlings in a coastal forest plantation. Seedling height growth and survivorship were measured annually in nine plots, with three plots each selected from three ranges of plots at distances of 5 m, 15 m, and 25 m landward from the bush hedge/sand beach boundary from 2007 to 2014, 8 years after planting. Annual averages in seedling height growth significantly reduced in the 2nd and 3rd years of growth but appreciably stabilized from the 4th to 8th year, indicating that the 2nd and 3rd years of seedling growth and survival in the study site were the most critic...

Wind-blown sand disasters, as an environmental problem, have great impact on human activities. Sand fence has been recognized as an efficiency technology in anti-desertification engineering and is wildly applied to protect highways and railways around the desert. But few people study its protection to Gobi buildings, which may also suffer from sand disaster. To study its protection to Gobi buildings, we systemically investigate the three-dimensional structure of wind field and sand distribution around sand fence for buildings by Computational Fluid Dynamic simulations and wind-tunnel experiments. The dependencies of sand-prevention efficiency on fence height, porosity, inclined slat angle and wind speed are proposed respectively. An optimal height of sand fence is suggested to be 2.0 m−2.5 m, and an optimal porosity is 10%−15%, by synthetically considering the factors of sand prevention efficiency and construction cost; the slat angles of inclined fence is recommended as 135°−150° for maximizing the sand sedimentation on the windward side of fence.

Sand fences are widely used to control sand deposition to initiate or stabilize dunes. Previous studies on sand fences are often focused on the porosity control of their trapping efficiency, however, there exists very little research on the fence height effect. We deployed fences with three heights and equal porosity at a field site near Jericoacoara, Brazil, and examined the variation of their topographic profile and trapping efficiency. We identified two stages of dune development around fences. During stage I, dune topographic profile area is proportional to the fence and dune height, and the trapping efficiency decreases substantially with time. During stage II, dunes continue to grow horizontally and the trapping efficiency decreases with time, but at a slower rate compared to stage I. Coarser sand tends to deposit close to the fence. The findings from this study can enhance the understanding of the complex wind-sand-structure interactions and provide insights for future dune recovery applications.

Sand fences are a frequently used management tool on developed coastlines because they are inexpensive and easy to install. While the geomorphic effect of sand fences has been investigated before, previous studies have been limited in both temporal and spatial domains. Here, we present the evolution of Bogue Banks, a developed barrier island along the Outer Banks of North Carolina, over a 20-year period from 1997 to 2016 where sand fences were emplaced along parts of the island in 2010. We use LiDAR-derived cross-shore transects (n = 38,454) to measure beach and foredune features along the extent (~40 km) of Bogue Banks for every available year of lidar data as well as the locations of sand fences, which we identify in 39% of the transects following fence construction. First, we found that vertical growth of the natural foredunes along Bogue Banks was slightly positive between 2010 and 2016 despite an increased amount of shoreline erosion. This pattern was coincident with a combination of sand fence installation and beach nourishment efforts, which were most heavily focused on the eastern end of the island. Second, we found that natural foredunes located behind fenced dunes are typically shorter, wider, and smaller in volume than natural foredunes in non-fenced and undeveloped areas. Although this may partly be due to a tendency for fences to be installed in front of more vulnerable dunes, our results suggest that, once emplaced, sand fences prevent growth of the landward foredune behind fenced dunes. These findings suggest that sand fences block sediment supply to landward dunes, leading to a shorter and wider complex foredune than would otherwise naturally occur.