Employing process knowledge of backward erosion piping to devise effective countermeasures

Abstract

Backward erosion piping is one of the four main types of internal erosion threatening dams, dikes and levees. The backward erosion piping process occurs in the foundation of these water retaining structures and forms a specific threat to the older constructions, which have been built in the past when proper knowledge about this failure process was still lacking. In case of recent constructions, remedial measures may still be required in case of increased hydraulic conditions caused by modifications to the structure like heightening, increased safety requirements or climate change. A detailed understanding of the processes leading to failure has been developed in the past decades by laboratory research, field experiments and case histories. This enables the design of effective countermeasures. Classic measures like increasing the seepage length still work of course, but measures reducing the groundwater flow or blocking the transport of particles without obstructing the groundwater flow tend to be more cost-effective and have a smaller spatial impact. Current research on the so-called coarse sand barrier, a single filter to be installed at existing dams, dikes and levees, is described in more detail.