Runoff and Erosion Modeling by AGNPS in an Experimental Mediterranean Watershed

Runoff and erosion in upland watersheds can have significant negative environmental impacts. The choice and design of appropriate erosion control measures can be aided by reliable predictions of watershed hydrologic response under different land use scenarios. In recent decades several computer models have been developed to simulate rainfall and runoff effects at the watershed scale. Although many experiments have been conducted to evaluate the use of available watershed models, more work is needed to assess and improve model reliability in different environmental situations. To this end, a small mountainous watershed mainly pasture, covering about 130 ha in Eastern Sicily, was equipped some years ago in order to further extend model testing to semi-arid Mediterranean conditions. A 6-year hydrological and land use database is available and soil-vegetation distributed parameters have been stored into a GIS. In the present paper the model AGNPS (Young et al., 1989) is implemented and applied to 20 events (10 of which including suspended sediment concentration measurements), occurring from 1997 to 2001, and model performance is analysed also after a first calibration test.