Delimitation of the transition zone between active and inactive gully erosion in the Chinese Loess Plateau

The interaction of various erosivities is the main factor that causes significant spatial differences in the gully development of the Loess Plateau. In some areas of the western Loess Plateau, the accumulation process is greater than erosion process, most of the gullies are in an inactive state while the loess gullies in the east is eroded with a high degree of active development. From the view of the geographical system boundary, there must be a transition zone with in the process of activity of loess gully erosion. In view of this geographical phenomenon, the definition of the erosion-active and erosion-inactive loess gully is given firstly, and then the objective existence of the transition zone is demonstrated. Based on the field investigation data and corresponding remote sensing images, the characteristic system of active and inactive loess gully is constructed. Combining the data of 1: 1000000 geomorphological map and 1: 10000 standard mapsheet of China, the loess erosionactive and erosion-inactive loess gully are identified by visual interpretation method, and the spatial location and trend of the transition zone are determined. The results show that the boundary is essentially a complex transition zone, and the core part is located in the middle of the Longxi Loess Plateau. The development characteristics of loess gullies in the transition zone and on both sides are also analyzed from the aspects of geology, natural environment and climate.