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: 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.
Hits
Hits
Downloads
Comment