The new assessment of soil erodibility in Greece

Erodibility designates soils' vulnerability to the abrading effect of erosion's climatic drivers i.e. precipitation and overland flow. This parameter is represented in the Universal Soil Loss Equation (USLE) and its successor (RUSLE), by the respective component (K-factor). Its accurate quantification is critical for modelling soil erosion. Yet, in many countries - Greece included - the process is hindered by the lack of high-quality field observations, evenly distributed in time and space. In light of the above, the study aims to develop the new soil erodibility map of Greece. The K-factor was calculated using the algebraic expression of the Wischmeier and Smith (1978) nomograph. The latter considers basic soil properties like granulometry, soil organic matter content, structure and permeability. Approximately 2800 soil samples were utilized, deriving from the European Land Use/Cover Area frame Survey (LUCAS) and the Greek National Agricultural Research Foundation (NAGREF) databases. Of them, 577 corresponded to croplands and 2113 to forests/rangeland. Erodibility was spatially interpolated utilizing the ordinary cokriging methodology. The mean nationwide value was estimated at 0.024 t ha h ha(-1) MJ(-1) mm(-1), ranging from 0.013 - 0.044 t ha h ha(-1) MJ(-1) mm(-1). After incorporating the surface stone cover effect, given the country's extensive coverage, mean K-factor value was reduced by 22 %, at 0.018 t ha h ha(-1) MJ(-1) mm(-1). The new maps (500 m resolution) improve the accuracy of the available K-factor delineation, developed by the EU at pan-European level. The sample network is denser (1 sample per 48 km(2)) and more evenly distributed throughout the Greek territory. Also, the geostatistical model was fitted focusing entirely on the specific attributes of Greece. The results were proportional to those yielded by national and international studies of local and national interest.