Combining Qualitative and Quantitative Methods for Soil Erosion Assessments : an Application in a Sloping Mediterranean Watershed, Cyprus

In arid and semi-arid regions, water erosion is difficult to model because of highly irregular precipitation regimes and changes in vegetation cover. The application of quantitative, process-based models at the catchment scale is often problematic because of large data requirements. Qualitative methods require less data and can be more easily performed in a relatively short time, but they are more subjective. The objective of this research is to develop an erosion assessment methodology that combines qualitative field surveys with quantitative model estimates. The qualitative World Overview of Conservation Approaches and Technologies (WOCAT) methodology is based on expert observations per mapping unit, while the Pan-European Soil Erosion Risk Assessment (PESERA) model simulates hill slope soil loss based on land cover, soil texture, meteorological data and slope profile. This study was conducted in the 106·4-km2 Peristerona watershed in Cyprus with a mean local slope higher than 40% in the mountainous upstream area and less than 8% in the plain. Out of 68 units, PESERA and WOCAT results were in agreement in 40 units, while PESERA results were lower in 25 and higher in 3 units. Both methods identified burnt areas and complex cultivation patterns as the most degraded. The total PESERA-based sediment yield for the watershed was 1·2 Mg ha−1 y−1, which fell within the range of the sediment yield measured at the check-dam downstream (0·2–2 Mg ha−1 y−1). This study provides a linkage between qualitative and quantitative soil erosion methods and helps to translate the outcomes of the former into the latter, thus providing a good tool for local erosion assessment.