Journal of Geographical Sciences ›› 2021, Vol. 31 ›› Issue (11): 1575-1597.doi: 10.1007/s11442-021-1912-2

• Special Issue: Fluvial and Geomorphological Features • Previous Articles     Next Articles

Spatial distribution and influencing factors of Surface Nibble Degree index in the severe gully erosion region of China's Loess Plateau

ZHOU Yi1,2(), YANG Caiqin1,2, LI Fan1,2, CHEN Rong1,2   

  1. 1. School of Geography and Tourism, Shaanxi Normal University, Xi'an 710119, China
    2. National Experiment and Teaching Demonstration Center for Geography, Xi'an 710119, China
  • Received:2021-05-17 Accepted:2021-08-19 Online:2021-11-25 Published:2021-11-25
  • About author:Zhou Yi (1984-), Associate Professor, specialized in loess landform digital terrain analysis.E-mail: zhouyilucky@snnu.edu.cn
  • Supported by:
    National Natural Science Foundation of China(41871288);National Natural Science Foundation of China(41930102);The Fundamental Research Funds for the Central Universities(GK202003064)

Abstract:

In China's Loess Plateau severe gully erosion (LPGE) region, the shoulder-line is the most intuitive and unique manifestation of the loess landform, which divides a landform into positive and negative terrains (PNTs*The spatial combination model of PNTs is of great significance for revealing the evolution of the loess landform. This study modeled and proposed the Surface Nibble Degree (SND), which is a new index that reflects the comparison of the areas of PNTs. Based on 5 m DEMs and matched high-resolution remote sensing images, the PNTs of 172 complete watersheds in the LPGE were extracted accurately, and the SND index was calculated. The spatial distribution trend of SND was discussed, and the relationship between SND and the factors that affect the evolution mechanism of regional landform was explored further. Results show that: (1) The SND can be calculated formally. It can quantify the development of the loess landform well*2) The SND of the LPGE has evident spatial differentiation that increases from southwest to northeast. High values appear in Shenmu of Shaanxi, Shilou of Shanxi, and northern Yanhe River, whereas the low values are mainly distributed in the southern loess tableland and the inclined elongated ridge area of Pingliang in Gansu and Guyuan in Ningxia*3) In the Wuding River and Yanhe River, the SND decreases with the increase in flow length (FL*In the North-Luohe River and Jinghe River, the SND increases with FL*4) SND is significantly correlated with gully density and sediment modulus and moderately correlated with hypsometric integral. As for the mechanism factors analysis, the relationship between loess thickness and SND is not obvious, but SND increased first and then decreased with the increase of precipitation and vegetation in each geographical division, and we found that the land use type of low coverage grassland has greater erosion potential.

Key words: digital elevation model, shoulder-line, Surface Nibble Degree, spatial distribution, terrain factor, digital terrain analysis, Loess Plateau gully erosion region