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 2023-02-27 Cooperative journals: 《干旱区地理》
Abstract： The landscape diversity index (LDI) is not only an important indicator in landscape ecology research but also an important component in biodiversity conservation. Based on the land use/cover raster data (30-m resolution), the spatiotemporal variation and scale- dependence characteristics of the LDI of an oasis along the Yellow River in Ningxia, China, have been studied using Neighborhood and Focal tools in ArcMap from 1975 to 2000. The results are as follows: (1) The LDI, which is measured by a square with a side length from 90 m to 6000 m, had obvious spatial scale-dependent characteristics based on five times repeat, and its turning point was 3000 m. (2) The change trend of the LDI had been cyclical in the past decades, with a turning point of 2000. During the study period, the LDI exhibited a decreasing trend from 1975 to 2000, and the analysis of LDI zoning indicated that the main characteristics were as follows: the class area (CA) of the degraded area was the largest, and the CA of the improved area was the smallest, which were 6840 km2 and 1332 km2 , respectively. In contrast, there was an increasing trend for the LDI from 2000 to 2020, mainly characterized by the maximum CA in the impervious area and the minimum CA in the degraded area, which were 7848 km2 and 792 km2 , respectively. Because the initial LDI in 2000 was the lowest in the entire period, its improvement status in the later period did not reach that of the early period. (3) The conversions of the LDI-grading area were mainly characterized by the transfer from the early improved area to the late impervious area (796 km2 , 60.5% of the improved area) and the transfer from the degraded area to the impervious area (3519 km2 , 51.5% of the degraded area) and the improved area (3036 km2 , 44.4% of the degraded area), respectively. (4) The change in the landscape diversity pattern was characterized by a negative correlation between CA and relative splitting index, and this relationship mechanism was universal in different periods and change types. Thus, it is to best understand the landscape diversity change with credible spatiotemporal scales in a regional landscape study. It is necessary to ensure that the research results are not only used for reference and sharing but also used to visualize and analyze regional landscape diversity
Subjects: Geosciences >> Other Disciplines of Geosciences submitted time 2019-09-11 Cooperative journals: 《干旱区地理》
Abstract：基于实地调查研究，结合现有资料和研究成果，总结分析白龙江中游地理环境结构特点，调查研究该区水土流失性质、带状分异特征以及小流域形态结构，剖析地理环境与水土流失作用关系，提出以小流域为单元，以其空间结构有序和区段功能有序特征，配置水土保持防治措施体系，为建立综合治理模式提供有效参考。
Subjects: Geosciences >> Other Disciplines of Geosciences submitted time 2019-09-11 Cooperative journals: 《干旱区研究》
Abstract：陡削以兰州新区的一段陡峭边坡作为试验地点，通过分析在植被重建初期经人工整地后形成的4种微地形(大圆形坑、小圆形坑、条形坑和原状坡面)的植被盖度特征及环境因子(土壤硬度和水分、地表和空气温度、坡位、无纺布)对植被盖度的影响，探寻能有效提高植被盖度的几种工程改造措施。研究表明：① 铺设了无纺布坡面的植被盖度显著大于对照坡面；陡峭边坡不同坡位的植被盖度：下坡位＞中坡位＞上坡位(P＜0.05)，这与自然坡面植被盖度分布规律一致。② 3种微地形的植被盖度均显著大于陡峭坡面，其中条形坑的土壤水分和植被盖度最大，最大盖度维持的时间最长。③ 微地形和坡面的植被盖度均与土壤水分呈显著正相关，与空气温度、地表温度均呈显著负相关；微地形的土壤硬度(3 kg·cm-2)适宜植物生长，大于该值会对植被生长产生抑制作用；铺设无纺布有利于促进上坡位的植被生长，使坡面植被分布更均匀。研究结果表明，在陡峭边坡坡度、坡位和温度等无法改变的情况下，选择对压实的坡面进行整地翻耕处理，增加长条坑的数量并铺设无纺布等有效的工程改造措施，能显著增加植被盖度，促进植被恢复。
Subjects: Geosciences >> Atmospheric Sciences submitted time 2018-11-13 Cooperative journals: 《干旱区地理》
Abstract： 冰川融水径流的发育和形成过程中，存在大量水化学侵蚀，尤其是K/Na长石及碳酸盐的水解作用，可能消耗水体中H+，促使大气CO2溶于水形成重碳酸盐，影响区域碳循环。2015-7-21～2017-7-18选取相对平坦开阔的西天山科其喀尔冰川表碛物覆盖区利用涡度相关法进行CO2通量监测，结果表明：大气CO2通量介于-17.99～3.59 g•m-2d-1之间，平均为-2.58 g•m-2d-1，说明研究区是一个显著的碳汇。净冰川区系统CO2交换量主要受大气CO2通量支配，但日内变化显著，白天因冰雪消融导致大气CO2沉降于融水中促进区域水化学侵蚀，而夜间因太阳辐射减少，冰雪消融减弱甚至停止，抑制了区域CO2沉降，甚至再生冰的形成引起溶解于液态水中的CO2释放。净冰川区系统CO2交换量与气温呈显著的负相关关系，即气温升高，大气CO2沉降量增加；当降水量小于8.8mm时，交换量随降水量变化不显著，而降水量大于8.8mm时，CO2沉降量随降水量增加而减少。净冰川区系统CO2交换量随日径流量的变率遵循：积雪消融期＞积雪积累期＞冰川消融前期＞冰川消融后期＞冰川消融峰期，意味着积雪消融存在时，系统CO2交换量随日径流量变率较大，可能是因积雪本身的阻尼作用或积雪期水文通道不发育，积雪融水较冰川冰融水汇集相对较慢，为可溶性物质化学反应提供充分时间，增强了CO2沉降。
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