Evaluating soil erosion risk in olive orchards through drone-based monitoring and field experiments

Soil erosion represents one of the most pressing environmental challenges in Mediterranean regions, driven by the synergistic effects of climate change and unsustainable agricultural practices. Inappropriate techniques, such as plowing and herbicide application, combined with extreme weather events, including extended droughts and intense rainfall, accelerating water erosion, leading to soil degradation. These processes reduce soil fertility, decrease agricultural productivity, and increase flood risks, threatening both ecosystems and local livelihoods. Olive orchards situated on sloped terrains are particularly vulnerable due to their location and reliance on traditional farming methods. Thus, developing precise methodologies to monitor and mitigate soil erosion is critical for promoting sustainable agricultural practices and adapting to a changing climate. In collaboration with local stakeholders, we investigated a traditionally managed olive orchard in Messenia, Peloponnese, Greece, characterized by a 16% average slope and routine herbicide application. To quantify soil erosion, an experimental plot (100 m²) was established, with surface runoff collection systems installed to capture soil loss and sedimentation following rainfall events. The subplot was enclosed with metal sheet boundaries and equipped with guiding canals leading to buried tanks for sediment collection. To enhance field measurements, drone-based Digital Elevation Models (DEMs) generated with a LiDAR-equipped DJI MATRICE 350 RTK were used to map soil displacement before and after rainfall events. The Difference of DEMs (DoD) methodology, achieving millimeter-level accuracy, validated sediment data collected from experimental subplots. By capturing high-resolution topographic changes, this technique enabled precise quantification of soil displacement, offering a comprehensive view of erosion dynamics in response to varying agricultural practices and the influence of precipitation patterns on runoff and soil loss. The findings reveal significant variations in soil erosion rates across the two methodologies. Field measurements showed a soil loss of about 0.6 tons per hectare, while drone-based LiDAR estimated a higher loss of 1.2 tons per hectare. This difference suggests that remote sensing captures not only exported sediment but also subtle surface changes like compaction. By combining both methods, the study provides a more complete and accurate understanding of erosion patterns. This integrated approach supports better decision-making for sustainable land management in vulnerable sloped olive orchards facing increasing climate pressures.