Articles | Volume 19, issue 4
Technical note
20 Apr 2015
Technical note |  | 20 Apr 2015

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

J. Bechet, J. Duc, M. Jaboyedoff, A. Loye, and N. Mathys

Abstract. To investigate the millimetre-scale surface processes caused by natural rainfall, an undisturbed sample of badlands soil (1 m long, 0.5 m wide and 0.15 m 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°) 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.

Short summary
High-resolution three-dimensional point clouds are used to analyse erosion processes at the millimetre scale. The processes analysed here play a role in the closure of cracks. We demonstrated how micro-scale infiltration can influence the degradation of soil surface by inducing downward mass movements that are not reversible. This development will aid in designing future experiments to analyse processes such as swelling, crack closure, micro-landslides, etc.