érosion par contact

CONT: Mineral clogging starts to develop at the interface between the geotextile (or pipe wall) and the adjacent soil. It is therefore defined as a contact process. Two clogging processes can be distinguished: contact erosion ... which occurs when particles of nearly all sizes are washed out locally and contact suffosion ... when only the fine particles are washed out leaving a skeleton, consisting of coarser particles, behind. In subsurface drainage systems, contact erosion should be restricted. Contact suffosion is allowed, provided however that the envelope does not clog.