1. Department of Geography, Soil Erosion Laboratory; Universidade Estadual do Centro-Oeste - UNICENTRO; St. Simeão Camargo Varela de Sá, 03 - PO Box, 3010. Guarapuava Estado do Paraná Brazil 85.040-080
2. Department of Geography and the Environment & Lozano Long Institute of Latin American Studies; The University of Texas at Austin; 305 E. 23rd Street, CLA 3 .306 Austin TX 78712 USA