Landscape evolution and engineering geology: results from IAEG Commission 22

Commission 22 was set up following the 10th IAEG Congress to provide guidelines for incorporating a geomorphological understanding of landscape evolution into engineering geological practice and this paper presents the findings of the Commission. The concept arose from the recognition that landscapes are not static entities during the design life of an engineering structure and that anticipating the changes that will occur should be regarded as a fundamental component of the ground model developed for a construction project. Whilst not all aspects of long term landscape evolution fit easily with engineering projects that have a 100 years design life, there are shorter term processes that do require careful evaluation and incorporation in a site investigation. Concepts of landform equilibrium, geomorphological process-response systems, geohazards, climate and lithologically controlled landscapes, and complex landform assemblages within a palimpsest context, all provide important input for the creation of a four dimensional ground model as required by good ground engineering practice. These concepts are explored in this paper in relation to themes that have a long history within engineering geology and ground model development: geohazard assessment, reactivation of relict processes, design life, risk registers, reference conditions, effects of climate change, magnitude and frequency of natural processes, and cost benefit analysis. Some thoughts on how landscape evolution might influence construction contracts are also explored and suggestions made on incorporating methods for establishing landscape evolution in site investigations.