Hydrodynamics in erosion by dissolution: morphology and dynamics – ERODISS

Landscapes are shaped under water flows and wind action. The understanding of their morphodynamics goes through the identification of the physical mechanisms at play. The processes of erosion of sediment composed of macroscopic grains have been extensively studied with a physics approach, which is not the case of the erosion by dissolution. However, this process plays a significant role in area covered by a dissoluble mineral like limestone in Karst regions and is the cause of the formation of remarkable patterns (limestone pavements, scallops, dissolution flutes, dissolution pinnacles, limestone forests…) with characteristic and well defined length scales. We propose, by the means of well controlled laboratory experiments in model situations, to study the morphogenesis of dissolution patterns. The dissoluble media and the hydrodynamic flows will be tuned to downscale the characteristic size and time of the involved processes from geological values to values, which are manageable in the laboratory. Thanks to quantitative measurements of the flow and of the topography of eroded surfaces, we will identify the driving elementary physical mechanisms, which will be also numerically simulated. We intend thus to develop models, with the aim to explain morphology of complex geological systems and to deduce the laws controlling dynamics of erosion by dissolution coupled with hydrodynamics. To be able to predict the long term dynamics of landscapes, it appears necessary to take into account this small scale phenomenon. Furthermore, this study of dissolution and precipitation processes will find practical applications like the prevention of collapses of dissolution cavities, the aging of building materials under acid rains or the deposition and the corrosion of pipelines.