Modelling surface geomorphic processes using the RUSLE and specific stream power in a GIS framework, NE Peloponnese, Greece

Abstract

Mediterranean regions, with climate variability and long histories of human disturbance, are particularly vulnerable to soil erosion and sediment redistribution. This study examines surface soil stability and stream energy of the 243 km2 Inachos River watershed in the northeast Peloponnese, Greece. This mountainous, semi-arid Mediterranean region has an extensive history of human activity. Soil loss and stream energy are each quantified by applying the Revised Universal Soil Loss Equation (RUSLE) using the Unit Stream Power Erosion Deposition (USPED) method and the specific stream power approach to the main river channels. These models are used to indicate the spatial variability in geomorphic activity. Results show an average soil loss for the Inachos River catchment of 15.0 t ha−1 a−1, exceeding the rate of soil formation. Values range from nil in low gradient environments to 4287 t ha−1 a−1 in steep, mountainous regions. Gradient and rainfall erosivity are the primary factors. High specific stream power in the upper watershed exceeds 17,100 W m−2, resulting in the mobilization of sediment into channelized debris flows that transport sediment from the steep hillslopes. Episodic high-magnitude precipitation events promote the longitudinal connectivity of the catchment. The long occupation and agricultural history, extending as far back as Neolithic time, has accelerated downslope sediment transport.