Effects of Event Rainfall Properties on Permanent Gully Erosion
Description
Design and calcaluation
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1） The investigated PGs are situated in Zhifanggou small watershed of the Loess Plateau of China, with a longitude range of 109°13’ - 109°16’, and a latitude range of 36°42’ - 36°46’. 2） The rainfall was monitored using the Davis Vantage Pro2 (6152) miniature weather station and the 6465M self-calibrating rain gauge. 3） The observation was conducted continually in 2023 and 2024. In May of each year, the elevations of the 13 PGs were measured using real-time kinematic with Global Navigation Satellite System (GNSS-RTK). The measurement points were set at 20 cm intervals. Additionally, the efforts were made to capture the points along the edges and bottom lines of the PGs to best represent the PG's morphological characteristics. In areas with distinct terrain changes, additional points were recorded to capture the subtle topographical variations. The measurement range covered the entire PG and a 2-meter buffer zone beyond the PG edge. After each rainfall event, if obvious expansion was observed along the PG edge, it was considered as the evidence of noticeable erosion, and then the elevations of gullies were measured by GNSS-RTK. 4） The gully perimeter and projected area were calculated using the geometric calculation tools in ArcGIS 10.3. Subsequently, the headcut retreat distance (HRD) of the PG between two consecutive rainfall events, the variation in projected area (Va), and the variation in perimeter (Vp) were calculated based on changes in gully length, projected area, and perimeter. The PG erosion was determined by analyzing the change in elevation between two consecutive rainfall events. Areas with a decrease in elevation were classified as erosion zone, while regions with elevation increase were identified as sediment deposition zones. Erosion caused by the retreat of gully head (SEpgh) and the sidewall–floor (SEpgs) was further classified based on the identified PG edge for each rainfall event.
Institutions
- Beijing Normal UniversityBeijing, Beijing