A quantitative model for predicting gully erosion risk in karstified Mediterranean environments: Lebanon case study

Abstract

S oil erosion is a major land degradation problem in Mediterranean environments leading to great annual loss of natural resources. This has resulted in the development and/or testing of numerous models designed for quantifying soil loss or pinpointing to areas that are suffering from soil erosion. The advent of geographic information systems (GIS) has promoted an explosive growth in the number and variety of GIS-based model applications at catchment and larger scales during the past decades. Though a lot has been done and achieved in erosion research, there is no emphasis on predicting erosion hazard on the peculiar and attractive karst landscapes commonly distributed in the Mediterranean region (for example, 70% of the total area of Lebanon). These environments are particularly fragile ecosystems for several reasons: (1) the predominance of thin soils with low fertility, which readily succumbs to desertification when soil erosion takes place under improper land management; and (2) nonenvironmentally sensitive human activities such as deforestation, burning, and overgrazing in many karst areas leave only barren soils subjected to the activity of intense rainfall. We have used GIS to conceptualize a regional quantitative empirical model specified to predict erosion in dynamic karst landscapes at a scale of approximately 1:100,000.