Sebastio

  • The tax of infiltration in arenaceous ground is bigger of what in argillaceous ground (WAR, 1998). We can consider the following types of pluvial erosion: Laminar erosion in ridges or ravinas and soil erosions. Erosion in sheet or to plate Occurs when the superficial draining is not concentrated in canals and yes if it distributes for the hillsides of dispersed form. When drawn out rains occur, the infiltration capacity of the ground is exceeded and then it starts to occur the draining. How much bigger the turbulence of waters, greater the erosive capacity. Although to be amena form of erosion, it is responsible for great damage to agricultural lands and for supplying great amount of sediment that goes to sand rivers, lakes and dams.

    Ravinas Ocorre mainly in ground unproctected of vegetal covering. They are formed when the speed of the flow of pluvial waters increases, concentrating itself in filetes and they become turbulent; or still when the capacity of water storage in the surface is exceeded and then it starts to occur the formation of ridges and ravinas in the top of the ground. This type of erosion is responsible for the fast assoreamento of fertile valley lands, of the fluvial stream beds, lakes and dams, facilitating the overflow of waters of its courses and provoking floodings. Soil erosions the ravinas can go deep and reach the fretico sheet. When this happens the natural flow of the underground water starts to act as transporting of particles of deep of the ravina, solapando its base and provoking the collapse of the headboard, in the known process as remontante erosion. From there resultant feio is known as soil erosions. In accordance with Sebastio professor (2011, p.75), ' ' Booroca is a hollowing or rasgo of the ground or decomposed rock, caused for the erosion of the sheet of superficial draining or subsuperficial.' ' The deforestation, forest fires and the pisoteio of the cattle contribute directly for the sprouting of this type of erosion, associates to the type of ground and amount of rains.