Slope spectrum critical area and its spatial variation in the Loess Plateau of China
Slope spectrum critical area and its spatial variation in the Loess Plateau of China
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DOI：
10.1007/s11442-015-1245-0
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发表时间：
2015-11
影响因子：
4.9
通讯作者：
Tang Guoan;Song Xiaodong;Li Fa-yuan;Z. Yong;Xiong Liyang
中科院分区：
文献类型：
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作者：
Tang Guoan;Song Xiaodong;Li Fa-yuan;Z. Yong;Xiong Liyang
坡度谱是研究黄土地貌特征的重要方法。确定临界面积是导出斜率谱的一项必不可少的工作。沿着研究区域的增大，导出的光谱变得越来越相似，使得它们的差异可以被忽略而有利于标准。随后，将测试大小定义为斜率谱临界面积（SSCA）。SSCA不仅是坡谱计算的基础，而且在一定程度上反映了黄土地貌发育的过程。高分辨率DEM是提取斜坡谱的重要手段。选取了北方黄土高原不同地貌类型的48个DEM进行试验。利用地统计学方法对SSCA的空间分布进行了研究，得出SSCA的值范围为6.18 km 2 ~ 35.1 km 2。初步试验结果表明，土壤侵蚀复合能力的空间分布与土壤侵蚀强度的空间分布相关，在一定程度上反映了地形的复杂性。坡谱临界面积呈现由北向南弱-强-弱的空间变化趋势。选取了4个地形参数，即沟道密度、坡度、地形驱动力（Td）和坡度（SOS）作为评价指标。SSCA与沟道密度、地形驱动力和SOS之间存在较好的指数函数关系，与坡度之间存在较好的对数函数关系。随着SSCA的增加，坡度偏度增大，沟道密度、地形驱动力和SOS减小。SSCA的空间分布与黄土地貌的演化具有相关性，可以作为黄土地貌的判别因子。随着黄土地貌从塬区向沟丘区的演变，也证明了SSCA能够代表当地地貌发育程度。黄土高原的临界稳定区代表了黄土地貌发育的程度。它的主要意义在于，稳定区域的概念可用于确定最小地理单元。
Slope spectrum has been proved to be a significant methodology in revealing geomorphological features in the study of Chinese loess terrain. The determination of critical areas in deriving slope spectra is an indispensable task. Along with the increase in the size of the study area, the derived spectra are becoming more and more alike, such that their differences can be ignored in favor of a standard. Subsequently, the test size is defined as the Slope Spectrum Critical Area (SSCA). SSCA is not only the foundation of the slope spectrum calculation but also, to some extent, a reflection of geomorphological development of loess relief. High resolution DEMs are important in extracting the slope spectrum. A set of 48 DEMs with different landform areas of the Loess Plateau in northern Shaanxi province was selected for the experiment. The spatial distribution of SSCA is investigated with a geo-statistical analysis method, resulting in values ranging from 6.18 km2to 35.1 km2. Primary experimental results show that the spatial distribution of SSCA is correlated with the spatial distribution of the soil erosion intensity, to a certain extent reflecting the terrain complexity. The critical area of the slope spectrum presents a spatial variation trend of weak-strong-weak from north to south. Four terrain parameters, gully density, slope skewness, terrain driving force (Td) and slope of slope (SOS), were chosen as indicators. There exists a good exponential function relationship between SSCA and gully density, terrain driving force (Td) and SOS and a logarithmic function relationship between SSCA and slope skewness. Slope skewness increases, and gully density, terrain driving force and SOS decrease with increasing SSCA. SSCA can be utilized as a discriminating factor to identify loess landforms, in that spatial distributions of SSCA and the evolution of loess landforms are correlative. Following the evolution of a loess landform from tableland to gully-hilly region, this also proves that SSCA can represent the development degree of local landforms. The critical stable regions of the Loess Plateau represent the degree of development of loess landforms. Its chief significance is that the perception of stable areas can be used to determine the minimal geographical unit.