Author(s): Jishan Yang; Wenyi Yao; Lingling Wang
Linked Author(s): Lingling Wang
Keywords: Gravity erosion; Loess Plateau; Gully slope; Valley evolution; Erosion pin
Abstract: Gravity erosion is active in the hilly-gully region of Loess Plateau, which contributes large amount of sediment yield by conveying the earth into valleys. Mainly using the erosion pins method, observation and survey on the gravity erosion were carried out in a small watershed of Qiaogou gully, and shear test was done to measure the shear strength of loess in the study area. Based on the field data, influence factors, the regularity of gravity erosion on the gully slope，and coupling relationships of the gravity erosion with evolution of the gull stages are studied in this paper. Results show that gravity erosion is an important role for the sediment yield in the gully, which is mainly controlled by slope gradient, rainfall and weathering, etc. These influence factors can reduce the internal friction angle and cohesion of the intact loess and therefore lead to lower the critical depth of the gravity erosion on the slope, and this is the main reason of the occurrence of the shallow gravity erosions. Gravity erosion is an important geomorphologic agent for the evolution of gully. Gravity erosion has different intensity in each stages of the gullies. So it is possible to estimate the intensity of gravity erosion by characters of the evolution stages of the gully. Finally, delivery processes of sediment produced by gravity erosion on the gully slopes are analyzed. Simple calculation of the ratio of sediment yield by gravity erosion to the total sediment yield in the gully are discussed.
Year: 2013