The studied area, located in the West Side of Rio de Janeiro City, is represented by two main geomorphological features: the Mendanha Massif constituted predominately by Tertiary alkaline rocks igneous, and the Fluvial plain, represented by Quaternary sand-loamy sediments of fluvial origin. The soil classes found in the Massif are Latossoil and Red-yellow Podzolic, and in the Fluvial Plain are Planossolo and Alluvial Soils. The climate is classified as the sub-humid dry megathermic. The Massif of Mendanha is an Ambiental Protected APA inserted, in the Atlantic forest Complex of the Rio de Janeiro county.
The two geomorphological domains were analyzed using the "Unit-soil" definition, representing the integration of the different environmental variables, in order to evaluate the impacts of the urbanization process in the degradation and reduction of the agricultural area. The Geographical Information System was used to improve this study. The maps of the Pedologic the Rio de Janeiro City / EMBRAPA, 1980" and the Planimetrical Base Maps of Rio de Janeiro City / IPLAN, 1997, in the scale of 1:50.000. were treated in the IDRISI System wide as version 2.0, SAGA/UFRJ and AutoCAD R14.
A reduction of 25,68% in the agricultural activity in the area was verified in the period between 1974 and 1998. Soils with high agricultural potential correspond 41,4% of the total area (30Km2), therefore just 11 Km2 of the area is used for this propose. This is related to the expansion of the agricultural activity from the plain to the slope area, pushed by the accelerated urban growth, the soil lost, and the lock of investiment and incentive for agriculture.
The problems of agricultural management and inadequate use of the soil aggravated, now, with the modifications in the occupation process, generating environmental transformations that are reflected rising the risk degree, both in the domain of the slopes, and in the fluvial plain.