Subjects: Geosciences >> Geography submitted time 2023-04-07 Cooperative journals: 《干旱区地理》
Abstract： Soil wind erosion is the primary stage and important component of desertification in arid and semiarid regions. Evaluating its possibility and potential risk for wind erosion control at the regional level is of considerable importance. In recent years, remote sensing and geographic information technology are often combined with mathematical methods to build a risk assessment model. However, the current risk models of wind erosion are still lacking in mechanical parameters. This study was conducted in the Hetao Plain of China, which is a typical region of wind erosion and desertification. Soil hardness and shear strength were measured in the field to determine the difference in soil erodibility among different land use types. Wind erosion risk was evaluated using fuzzy logic, analytic hierarchy process, and the weighted linear combination method based on the data of climate conditions, soil physical factors, topography, and vegetation characteristics. Then, the spatial distribution characteristics and causes of different risk areas were analyzed. The following results are presented. (1) The shear strength of land use types shows an increased tendency in the order of sandy land, grassland, woodland, cultivated land, and saline land, which agreed well with the soil hardness. The soil hardness and shear strength of sandy land are 2.05 kg·cm−2 and 10.00 kPa, respectively, which are significantly lower than those of other land use types, indicating that the soil erodibility of sandy land is extremely high. (2) The wind erosion risk varied in spatial distribution. Wind erosion hazard is high in the west and south and low in the eastern and middle regions. Moreover, 27.51% of the total areas are found to be at a high risk of erosion. Thus, soil erodibility and vegetation coverage are essential factors affecting soil wind erosion. (3) The severe risk region is mainly distributed in most of Dengkou County, the edge of the south bank of the Yellow River, Togtoh County, and the east of Wuliangsuhai in the Urad Front Banner. Therefore, this area should be the focus of wind erosion control. The current research demonstrates strong universality and compensates for the shortcomings of existing wind erosion models, which can provide a theoretical basis for regional-scale wind erosion assessment models.
Subjects: Biology >> Ecology submitted time 2023-03-13 Cooperative journals: 《干旱区研究》
Abstract： The understanding of the evolution process of barchan dune and its movement rate is an important prerequisite for wind prevention and sand fixation and ecological construction in Minqin oasis. Based on field measurement and high- resolution remote sensing image analysis, The study discusses the relationship between the morphological parameters of barchan dune and its movement rate in the upwind edge of Minqin oasis. The results show that: (1) The aspect ratio of the dunes remains a constant value of 16 in 16 years. (2) The average annual moving distance of the tall dune is less than 3 m, which is a medium moving speed. The shape of the tall dune is basically unchanged, and the change is obvious only at the baseline, ridge line, and wing Angle of the windward slope. Low dunes move fast, with an average annual distance of more than 10 m, which is an extremely fast-moving speed. (3) The downwind velocity of the dune is inversely proportional to its width, and the proportionality constant is 718.52 m2 ·a-1. In this area, the barchan dune is dominated by fast-moving speed, which is greater than 5 m·a-1, accounting for 52.63%. (4) During the process of sand erosion on the windward slope and deposition on the leeward slope, large dunes maintain stable morphology and move slowly. Small dunes change dramatically and move rapidly, and the dunes tend to shrink in development.
Subjects: Geosciences >> Geography submitted time 2023-03-13 Cooperative journals: 《干旱区研究》
Abstract： This study aimed to study the shelter efficiency of Haloxylon ammodendron windbreak with different density and plant point distribution to provide scientific basis for optimizing the structure of windbreak in arid areas. With the field Haloxylon ammodendron as the prototype, windbreaks with three stand densities and four plant point distributions were designed, and their flow field and shelter efficiency were measured and analyzed by wind tunnel experiments. The corresponding label and“plant spacing × row spacing”of the windbreaks were as follows: A: 17 cm × 17 cm, B1: 34 cm × 17 cm, B2: 17 cm × 34 cm, and C: 34 cm × 34 cm. Results showed that (1) the area of wind speed deceleration region (U/U0 < 1) accounted for 78.06%, 70.41%, 74.36%, and 82.80% of the whole flow field of A, B1, B2, and C windbreaks, respectively; the area of weak wind speed region (U/U0 < 0.4) accounted for 22.46%, 0.73%, 5.91%, and 0%. (2) The higher the stand density, the lower the average wind speed under the canopy, but the faster the wind speed recovered at the leeside of windbreaks. The minimum wind speed was located at 11H, 15H, 15H, and 20H behind the A, B1, B2, and C windbreaks, respectively (H was the tree height). (3) The order of shelter efficiencies of the four windbreaks from large to small was A > B2 > B1 > C. The relationship between shelter efficiency and stand density was nonlinear. The ratio of wind reduction at the near surface was A:B:C≈6:3:2 behind the windbreaks. The density of afforestation should be determined based on the soil water carrying capacity in the practice of forestation. On this basis, the plant point distribution mode of“small plant spacing, large row spacing”should be preferred.
Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology submitted time 2020-06-30 Cooperative journals: 《干旱区研究》
Abstract：分析植被覆盖和人工扰动下戈壁地表的风沙流结构和摩阻风速与输沙率之间的关系，对保护戈壁区的生态环境具有重要意义。本文分别对植被覆盖下的戈壁地表和人工清除植被后的戈壁地表进行研究。结果显示：在不同的地表条件下，风沙流结构的变化趋势基本相同，大致可以分为3类：波动减少、先增加后减少和单调减少。受扰地表的输沙率密度大于原始地表。将摩阻风速以0.50 m·s^(-1)为界分为高、低风速。在植被覆盖的地表中，高、低风速区的输沙率与摩阻风速之间没有明显的线性相关性；而在人工清除植被后的地表，高风速区内，输沙率与摩阻风速之间满足传统的低阶多项式的关系，低风速区内两者之间则没有线性关系。
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