Material and Methods

Study area

Jiuyuangou watershed (37°33′ to 37°38′ N, 110°16′ to 110°26′ E) is in the hilly and gully region of the Loess Plateau and a first-class tributary on the left bank of Wuding River in Yulin City, Shaanxi Province, China(Figure 1). The basin has a gully density of 5.34 km km–2, area of 70.7 km2, and altitude of 820 to 1180 m. The main soil type is Malan loess, which is loose, porous, and prone to erosion. The basin topography is representative of the hilly and gully region of the Loess Plateau. In 1953, the Yellow River Water Conservancy Commission established the Suide Test Station in Suide, and determined Jiuyuangou—the representative area of the first sub-area of the Loess Hills and Gully region—as the Yellow River soil and water conservation ecological construction demonstration area.