Spatial distribution and morphologic characteristics of gullies in the Black Soil Region of Northeast China: Hebei watershed. (3rd July 2016) - Zhang, Tianyu
Abstract: Gully erosion in the Black Soil Region of China has posed a threat to food security. This study aimed to determine the spatial distribution and morphologic characteristics of gullies in the region and their topographic thresholds. A 28 km 2 watershed was surveyed and 117 gullies measured. The results showed that: (1) Gullies were distributed equally on both hillslope and valley floor positions, with a total gully density of .66 km/km 2 . (2) The mean depth, width, and cross-sectional area of gullies were .74 m, 2.39 m, and 2.43 m 2, respectively. These characteristics varied among gullies according to their topographic positions and slope gradients. Individual gully volume ( V ) was well predicted from gully length ( L ) by V = 2.08L 0.96 ( r 2 = .66). Total gully volume ( V ) of each sub-watershed was predicted from mean slope gradient ( S ) and drainage area ( A ) as V = 275800S − 8600A ( r 2 = .73). (3) Gully erosion was more serious in steeper sub-watersheds and steeper hillslope positions. Gullies were wider in regions with relatively larger drainage areas, except for those developed in the main valley. The topographic threshold for gully initiation was S = .10A −0.34, which indicated gully erosion was dominated by surface runoff. (4) Human activities, such as road construction, played a significant role in gully erosion.