Erosion processes in black marl soils at the millimetre scale: preliminary insights from an analogous model

To investigate the millimetre-scale surface processes caused by natural rainfall, an undisturbed sample of badlands soil (1m long, 0.5m wide and 0.15m thick) was carefully extracted. The sample is composed of black marl soil from a badlands area of the Draix Observatory (SE France). After extraction, the undisturbed sample was placed at the same slope angle (45 degrees) as its original orientation and was then monitored for several processes via a terrestrial laser scanner (TLS) with millimetre-scale accuracy and resolution. This experiment identified several surface processes interpreted as micro-landslides, swelling of the black marl material and lateral expansion that closed desiccation cracks. These micro-processes illustrate the complexity of the surface micro-topography changes that control erosion and infiltration rates over time.