Measuring the volume of eroded material in ravines based on the use of photographs obtained with Remotely Piloted Aircraft (RPA)

Abstract

Soil conservation is a fundamental step in agricultural systems, especially when the aim is to balance productivity and the environment. When not carried out, the soil is susceptible to the action of erosion processes, which can culminate in large impacted areas called gullies, whose recovery depends on a financial and time-consuming project. The measurement and digital cartographic generation have evolved a lot, when compared to conventional measurement methods, in this sense, the use of Remotely Piloted Aircraft (RPA's) is a technique with the highest growth in the mapping market. This work aims to validate the methodology for mapping and calculating the volume of eroded soil in gullies from a digital terrain model prepared through aerial photogrammetry obtained by RPA, using conventional topography techniques as a control treatment. In a rural area with gullies with an area of approximately 8.32 hectares, a topographic survey of 940 points was carried out with a laser total station, by walking and georeferenced polygon embedded by GNSS L1/L2 receiver. 2 missions were carried out with low-cost RPA, with a 90º change in the flight plans. The photos obtained will be processed in Agisoft Metashape following different rigors in the generation of the point cloud. The volume of eroded material from the gully to the downstream source was 638641.5 m³, equivalent to 212880 conventional buckets for transporting debris of 3 m³.