Quantitative effect of lithologic-geomorphic coupling on gully distribution at the regional scale: An example of the Dry Valleys (SW China)

Gully erosion is an important soil erosion type that destroys the surface structure and causes severe soil and water loss. Currently, the quantitative relationship between the spatial distribution of gullies and lithologicgeomorphic coupling is unclear. Gullies were interpreted by using high-resolution remote sensing image data to establish a database. Correlation analysis and geographic information technology were used to quantify the correlation between the gully distribution and lithologic-geomorphic types. The results show that the gully spatial distribution is characterized by clustering, and the lithologic-geomorphic type has a large effect on the spatial distribution of gullies. The coupling zone of phyllites and schists and intermediate-relief and intermediate-altitude mountains (P-II) has the greatest clustering; the zone of loose Quaternary sediments and intermediate-altitude plains (L-IP) has the least clustering. The lithologic-geomorphic coupling affects the initiation, development, and distribution of gullies; the more fragile the lithology and the greater the relief amplitude, the easier it is for gullies to form. This study will make it possible to better understand the distribution pattern and formation mechanism of gullies at a regional scale, and it will also provide a scientific reference for regional gully management.