A Review of Spatial Monitoring of Piping Collapse Using Unmanned Aerial Vehicle in Loess-Derived Soils in the Golestan Province

Piping erosion is an influential landform of intensified water erosion that interact with each other in the loess-derived soilsof the Province of Golestan (NE Iran). This study attempts to emphasize the use of high-precision data through field surveys and UAV images, and then to establish a threshold to study the factors that affect piping erosion. The present study was carried out using photogrammetric drones in an area of ​​approximately 2700 hectares in the loess lands in the east of the Province of Golestan and identified areas affected by piping erosion. A total of 833 pipes were recorded using the GPS and the orthophoto images from the UAV. Topographic, hydrological, and biological factors were treated as independent variables and piping erosion as dependent variables through statistical analyzes. The topographic factors indicated that the maximum density of piping occurred at altitudes of between 300–350 m, at maximum slope of more than 30%, at slope length less than 5m, and in concave tracts and profile curvatures. Regarding the hydrological factors, the maximum piping density occurred at the maximum numerical value of the topographic wetness index (more than 12), and at the closest distance to waterways (less than 100m). Biological factors indicated that the maximum density of pipes is in the rangelands and where this erosional facies is closest to the roads. Therefore, it can be suggested that an accurate identification of the piping erosion is facilated through ground observations aided by high-precision areal photography and understanding causative factors developing them.