2.4 Extraction of morphological features of gullies
The gully recognition and DEM data were imported into ArcGIS software to
extract the morphological features of gullies (e.g., number, length,
width, area, frequency, density, and dissection degree) using Spatial
Analyst and 3D Analyst tools. The attribute calculation function is used
to obtain the projected gully length, which is divided by the cosine
value of the corresponding slope to obtain the gully length. The
distance measurement function is used to calculate gully width from the
horizontal distance of five equally spaced sections. The gully area is
the gully width multiplied by the corresponding gully length. Gully
frequency is the number of gullies per unit area of the watershed,
reflecting the erosion intensity of gullies in the watershed. Gully
density is the total length of gullies per unit area of the watershed,
reflecting the length characteristics of gullies in the watershed and
the degree of surface fragmentation. The dissection degree of gullies is
the total area of gullies per unit area of the watershed, reflecting
gully development in the watershed.