1. Department of Agricultural and Environmental Science; University of Bari; via Amendola 165/A Bari 70126 Italy
2. USDA-ARS-National Sedimentation Laboratory; Watershed Physical Processes Research Unit and Water Quality and Ecology Research Unit; Oxford MS U.S.A.
3. National Research Institute for Rural Engineering, Water and Forestry, (NRIREWF); Rue HédiKarray, El Menzah 5, BP No. 10 2080 Tunis Tunisia