陕北黄土高原水蚀沟谷多维度侵蚀特征量化研究

沟谷地是黄土高原地貌形态特征变化最明显的区域,其发育对整个黄土高原地貌发育具有重要的控制性作用。论文基于5 m分辨率的DEM数据,在陕北黄土高原遴选包含15种地貌类型的42个样区,以沟谷密度、水平逼近度与切割深度作为纵向、横向与垂向3个维度的代表因子,分析了沟谷的多维发育进程、特征、空间分异及影响因素。研究结果显示：陕北黄土高原南北方向上沟谷发育呈现由溯源侵蚀主导转向横向溯源侵蚀主导、溯源下切侵蚀主导到横向溯源侵蚀主导,54.8%的样区各维度对整体发育进程的影响程度相近,且86.4%处于陕北黄土高原中部地区,即中部地区多维度发育均衡,南北两端以溯源侵蚀与横向侵蚀为主。结合面积—高程积分分析发现沟谷发育可划分为3个阶段：发育初期以溯源侵蚀为主,带动下切侵蚀伴有横向侵蚀;发育中期以溯源侵蚀为主,伴有持续性横向侵蚀与较强下切侵蚀;发育晚期以横向侵蚀为主,伴有一定程度的溯源侵蚀与轻微下切侵蚀。黄土厚度对沟谷系统垂向下切侵蚀的影响最大(Cv=0.164),土地利用类型对沟谷系统横向侵蚀的影响较大(Cv=0.0681),林地对于维护各个维度的抗侵蚀能力最强,生长茂密的草地和灌木林及作物次之,生长稀疏的牧草和作物较差。

Quantitative analysis of multi-dimensional erosion characterstics of waterworn gullies on the Loess Plateau of Northern Shaanxi

Gullies are the areas with the most obvious changes in the morphological characteristics on the Loess Plateau, and their development has an important control effect on the development of the entire Loess Plateau region. Based on the digital elevation model (DEM) data at a resolution of 5 m, this study investigated 42 sites covering 15 geomorphological types on the Loess Plateau of Northern Shaanxi. Representative factors (gully density, lateral expansion degree, and downcutting depth) of the three spatial dimensions were used to analyze the multi-dimensional development process, characteristics, spatial differentiation, and influencing factors of the gullies. The results show that the development of gullies in the north-south direction of the Loess Plateau in Northern Shaanxi has shifted from traceable erosion dominated to lateral-tracing erosion, tracing-downcutting erosion, and lateral-tracing erosion. Of the sample sites, 54.8% have similar effects on the overall development process in each dimension, and 86.4% of these are in the central area of the Loess Plateau in Northern Shaanxi, that is, the central area has a balanced multi-dimensional development, and the north and south ends are dominated by traceable erosion and lateral erosion. Combined with the hypsometric index, we found that the gully development can be divided into three stages. In the early stage of development, traceable erosion is the main driving force, leading to downcutting erosion accompanied by lateral erosion, and in the middle stage of development, traceable erosion is dominant, accompanied by continuous lateral erosion and strong downcutting erosion. Later stage of development is dominated by lateral erosion, accompanied by a certain degree of tracing erosion and slight downcutting erosion. Loess thickness has the greatest influence on the vertical erosion of the gully system (Cv=0.164), and land use type has the greatest influence on the lateral erosion of the gully system (Cv=0.0681). Forestland maintains the strongest anti-erosion ability for each dimension, followed by dense grass and shrubs and crops, and sparse grass and crops are the poorest.