2.1 Study area
The research area of this study is the Zhoutungou watershed (36°42’10”
N to 36°47’10” N, 109°09’00” E to 109°13’45” E), a typical small
watershed in the hilly and gully region of the Loess Plateau, with an
average altitude of 1,235.37 m (Fig. 1 (a) and (b)). The annual average
temperature is 8.80℃ and annual average rainfall is 550 mm (74% falls
from July to Sept.). The soil type is loessial soil of the Zhoutungou
watershed. The total watershed area is 33.60 km2, with
18.70 km2 (55.57%) of valleys (Jiang et al. ,
1999). The ephemeral gullies are distributed mainly on slope surfaces in
the southern region, accounting for about one-third of the slope area.
The main measure for ephemeral gully regional governance is planting
grasses and shrubs. The main valley in the watershed runs southwest to
northeast, with the number of branch valleys gradually increasing from
northeast to southwest. The valley and branch valley sections have a ‘U’
or ‘V’ shape, with the terrain of each valley comprising hills, slopes,
and channels. In addition, we selected two slope types for field
investigations to obtain measured values of ephemeral gully
morphological parameters. Slope A is on sunny slopes, with an area of
22,532 m2. Slope B is on shady slopes, with an area of
11,004 m2 (Fig.1 (c)). We investigated 13 ephemeral
gullies on slope A and six ephemeral gullies on slope B.