Slope spectrum critical area and its spatial variation in the Loess Plateau of China

Abstract

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 km 2 to 35.1 km 2 . 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 (T d ) and slope of slope (SOS), were chosen as indicators. There exists a good exponential function relationship between SSCA and gully density, terrain driving force (T d ) 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.

Spatial variation of gully development in the loess plateau of China based on the morphological perspective

“…As one of the most typical areas of loess deposit in the world, the Loess Plateau of China that features unique loess landform and severe soil erosion issue has attracted widespread attention for scholars in the fields of geomorphology, geology, hydrology, ecology, and soil and water conservation (Shi and Shao 2000;Hessel and van Asch 2003;Tang et al 2008; Li and Tang 2011;Wang et al 2013;Tang et al 2015;Xiong et al 2016). Gullies, as vessels of material and energy transportation during earth surface processes (Perron et al 2009;Willett et al 2014;Shruthi et al 2015;Xiong et al 2017), are the most active geomorphic units and widely distributed in the Loess Plateau and other regions (Korzeniowska et al 2018;Li et al 2019).…”

Fingerprinting Sediment Sources After an Extreme Rainstorm Event in a Small Catchment on the Loess Plateau, PR China

“…This also indicated the variation in erosion pattern during the extreme rainstorm. Forest, grassland and cropland accounted for 62·2%, 27·1% and 6·9% of the area of the catchment, respectively, and the remaining 3·8% of the area resulted in a gully density of about 2·1 km −2 , which is much lower than the average gully density (approximately 8·3 km −2 ) in the hilly loess areas of northern Shaanxi Province (Tang et al ., ). Despite their relatively low density, these gullies were responsible for a large proportion of the erosion in the catchment.…”

Application of the Hilbert–Huang transform for recognition of active gully erosion sites in the Loess Plateau of China

“…The loess landform types in the three areas studied represent a loess tableland, loess ridge, and loess hill. The selected catchments are representative of loess landform types, as many previous studies can be found (Cao et al, ; Tang, Song, Li, Zhang, & Xiong, ; Xiong, Tang, Li, Yuan, & Lu, ; Zhou et al, ). The morphological features are significant when selecting sample areas, and areas with various mixed terrain features or transitional zones are largely avoided.…”