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

In China’s Loess Plateau severe gully erosion (LPGE) region, the shoulder-line is most intuitive and unique manifestation of loess landform, which divides a landform into positive negative terrains (PNTs). The spatial combination model PNTs great significance for revealing evolution landform. This study modeled proposed Surface Nibble Degree (SND), new index that reflects comparison areas PNTs. Based on 5 m DEMs matched high-resolution remote sensing images, 164 complete watersheds in LPGE were extracted accurately, SND was calculated. distribution trend discussed, relationship between factors affect mechanism regional explored further. Results show that: (1) can be calculated formally. It quantify development well. (2) has evident differentiation increases from southwest to northeast. High values appear Shenmu Shaanxi, Shilou Shanxi, northern Yanhe River, whereas low are mainly distributed southern tableland inclined elongated ridge area Pingliang Gansu Guyuan Ningxia. (3) Wuding River decreases with increase flow length (FL). North-Luohe Jinghe FL. (4) significantly correlated density sediment modulus moderately hypsometric integral. As analysis, thickness not obvious, but increased first then decreased precipitation vegetation each geographical division, we found land use type coverage grassland greater potential.