Morphology parameters of ephemeral gully in characteristics hillslopes on the Loess Plateau of China

The Loess Plateau of North China has one of the highest erosion rates in the world. Ephemeral gullies are an important erosion type found on hill slopes of upland areas, and soil loss due to these gullies equals 30–70% of total soil loss. In this study, we used a high-accuracy global positioning system (GPS) to measure the morphology of characteristic ephemeral gullies near Suide, Shaanxi Province. We discuss the geomorphological characteristics of the gullies (their length, the distance between the head of ephemeral gully and the watershed divide, the distance between two neighboring hill slope ephemeral gullies, the critical slope gradient, the upslope drainage area, and the flow erosivity). The length and average distance between gullies both followed a Pearson IV distribution function, but the function parameters differed. The product of upslope drainage area and the square of the critical slope gradient ranged from 4.74 to 892.66 m2 and can be used to determine locations where gullies are likely to begin in a digital elevation model with a 2 m × 2 m grid. The relationship between the upslope drainage area (A) and the critical slope gradient (S) could be expressed as S = 0.058A−0.3. For the first time, this paper determined the relationship between gully length (L) and flow erosivity (E): L = 0.0305E + 18.185 (R2 = 0.71). These results improve our understanding of the erosion process in ephemeral gullies.