The main environmental problem caused by land use in permanent protection areas along river banks is the removal of the primary vegetation. Depending on the type and intensity of use, the soil structure of this river banks can be altered and the physical functions modified, especially near the watercourses. The purpose of this study was to evaluate the structural sustainability of three classes of river bank soil using the preconsolidation pressure measurement and thereby assess the impact of these different land uses on river bank stability in the sub-basin of the Ribeira Valley, SP. The experimental area consists of three soil types, Cambisol, Ultisol and Gley soils. In the first analysis, the preconsolidation pressure of the three soil types under native forest and pasture was compared. The second analysis evaluated the influence of different land uses; banana cultivation, degraded pasture, native forest and silvopastoral use on the structure of the Cambisol. Our result showed that preconsolidation pressure values are useful tools to identify soil degradation in these protected areas, since the changing values adequately represent degradation tendencies. The land use in the permanent protection areas resulting in changed preconsolidation pressure tends to cause structural degradation, threatening the sustainability and stability of the land, and should not be allowed. The Gleysol showed higher values of preconsolidation pressure as a function of increasing water levels and, therefore, greater load support capacity than the Cambisol and Ultisol. Banana was the crop that degraded the soils in the permanent preservation areas most.
load support capacity; modeling; Vale do Ribeira
