The Manoel Viana municipality is located in western Rio Grande do Sul, in Ibicui River Basin. The altitudes are among the range of 80 m and120 m above the sea level, corresponding to 46% of the total altitude, and 120 m and 180 m above the sea level, which has approximately 49% ofthe total. The lowest altitude is approximately 60 m and it is along the plain of the Ibicuí river, and the highest altitude is approximately 240m,in the northeast region of Manoel Viana. The predominant declivity distance is less of 2%, with more than half the study area 56%, distributedat all altitudes, being characteristic of the plain reliefs, the broad interfluves and the tops of hills and hillock. The landforms can be classifiedas: ramps of valley bottom characterized by presenting a slope less than 2% occurring among the major drainages; forms of gently rolling hillswith slopes between 2% and 5% and wide lengths; forms of strongly wavy hills characterized by slopes between 5 and 15% that occur in thetransition area between two levels of dissection; isolated mounts characterized by amplitudes lower than 100m and steep slopes, associated withthe most resistant portions to erosion; and associated to mounts, forms of hills which are called sedimentary rocks from the formation of Guaráand Botucatu; the forms of mounts and hills associated to the strongly wavy hills, which characterize by slopes greater than 15%, occurring thetransition of the first to a second level of dissection.
