Environmental geotechnics for peatland management and restoration

Abstract

Peatlands are dynamic eco-hydrological wetland systems, increasingly under threat worldwide due to natural and anthropogenic effects, including large-scale drainage and oxidation, causing their subsidence and ecological deterioration. In Europe, the requirements for conservation, restoration and long-term sustainability of degraded active bog have been accentuated by more stringent environmental policy and legislation. This paper describes how peat bunds(dams), strategically constructed at affected areas around the bog margins,can gradually re-establish the natural peatland hydrology and peat-forming vegetation through collection, storage and controlled release of surface runoff from the high bog. For geotechnical stability, the translational-type slip failure was identified as the critical case. The analysis must account for drying out of the compacted peat during drought periods and ensuing increases in lateral and uplift hydraulic pressures and seepage pressures generated following torrential rainfall events. Various geotechnical issues, including how much the current soil mechanics framework, standard strength-measurement procedures and ways of evaluating pertinent parameters should be used in describing fibrous peat behavior,are also described. Finally, subsidence and/or restoration of peatland may occur over protracted time periods, making monitoring a challenge. In this regard, airborne LiDAR scanning and geophysical techniques provide rapid, economical topographic and depth profiling in peatlands, with the latter also providing engineering-property characterization, to augment conventional GPS surveying, auger and penetrometer methods.