Risk assessment methodologies of soil threats in Europe: status and options for harmonization for risks by erosion, compaction, salinization, organic matter decline and landslides

Abstract

The EU thematic strategy for soil protection recognizes that soil degradation through erosion, soil organic matter decline, compaction, salinization and landslides occurs in specific areas, and that these areas must be identified in an unequivocal way. Currently, there are various risk assessment methodologies (RAMs) and the question has risen to what extent these RAMs yield similar outcome and, if not, whether the outcome can be harmonized, i.e. whether the results of the various RAMs can be made compatible or comparable. In this study i) the current status of RAMs for erosion, soil organic matter decline, compaction, and salinization in the European Union (EU27) is reviewed, and ii) the need and the options for harmonization are assessed. The need for harmonization was defined as the likelihood of achieving different outcomes when using different RAMs, whereas the options for harmonization refer to the efforts that are required to harmonize soil RAMs. The current status of RAMSs in EU-27 was assessed on the basis of questionnaires, which were sent out to soil specialists and policy officers in all Member States. We received more than 100 (response rate >50%) completed questionnaires. It turned out that many of the so called RAMs are still incomplete; they are ‘process (or threat) quantifications’ rather than methodologies that assess the risk of a soil threat. Moreover, there were significant differences between RAMs for a soil threat in terms of (i) the notion of the threat, (ii) data collection, (iii) data processing, (iv) data interpretation, and (v) risk perception. The need for harmonization appeared highest for erosion and salinization, whereas the options for harmonization were best for SOM decline. Harmonization of soil RAMs may be very complex and for that reason not always feasible. We suggest two options that may facilitate unequivocal identification of risk (or priority) areas for soil threats, i) a two Tiered approach based on data availability and spatial scale and ii) generic harmonization, i.e. combining standardization and harmonization in a rather pragmatic way