Accuracy constraints of terrestrial Lidar data for soil erosion measurement: Application to a Mediterranean field plot

• Application of TLS at the performance limit in a Mediterranean soil erosion study
• Influence of scan geometry on quantification of soil surface changes at field scale
• Setup of a precise reference net for reliable multi-temporal change detection
• Mitigation of systematic data error revealed with an off-site calibration plot.
• Discontinues soil erosion patterns detected with Lidar

Applications of terrestrial laser scanning (TLS) to measure soil erosion are yet limited, although this topographic mapping method allows for large area coverage with high resolution and reliable precision. However, restricting factors are accurate and stable references for multi-temporal change detection and adverse scanning geometries. At agricultural fields the plot is usually situated on gentle slopes provoking low viewing angles of the scanning device onto the surface, which inherits the risk of high data noise. In this study, TLS is exploited from a high tripod to measure soil erosion at an Andalusian hillslope (2 × 1000 m2). In the Mediterranean sediment yield reveals discontinuous pattern and TLS is a promising method to quantify these surface changes. A stable reference system is defined, resulting in multi-temporal registration accuracy better than 7 mm. Further, an mm-accurate calibration plot (60 m2) is designed to evaluate scan geometry and radiometry (i.e. incidence angle, footprint, and intensity) in dependence of distance related errors. A lookup table is determined to correct systematic errors of the field data. The Andalusian field plot is captured during a winter season and during single precipitation events. Estimated erosion rates amount 10 and 2.4 t ha−1, respectively. Surface changes with magnitudes larger 1.5 cm are reliably measured. TLS can be implemented to estimate soil erosion with cm-resolution if errors are carefully accounted for.