Dinâmica da paisagem na região nordeste do estado do Rio Grande do Sul.

Abstract

Environmental analysis and land use dynamics of the landscape northwest area of the Rio Grande do Sul Province. With the growing demand for natural resources the environmental analysis and the periodic diagnosis of the land use started to represent a fundamental aspect for the understanding of the occupation patterns and spatial organization of the landscape, rarely permanent in function of the dynamics of the human activities. In this context, information obtained by orbital sensor, allied to the geocoded techniques constitute a fundamental tool to the landscape structural characterization and for the identification, mapping and environmental diagnosis of the natural resources. This work had as objectives the delimitation, and the environmental analysis and diagnosis of five watershed of the landscape northwest area of the Rio Grande do Sul Province, for the identification of the risks associated to the soil erosion and of the degree of compromising of the environmental quality related to fragmentation and loss of natural areas, that these landscape mapping units were submitted in the period from 1984 to 1999. The Geographical Information Systems (GIS) were essential to obtain information related to the structural characteristics of the landscape represented by the hypsometriy, clinografy, road net, hydrografy, land use types, and critical risks to soil erosion and permanent preservation areas. Agriculture represented the principal land use type in the period among 1984 to 1999, demonstrating the need to promote the control of the agricultural practices, mainly the execution of the environmental legislation toward to the establishment of permanent preservation areas. The application of Principal Components Analysis associated to the software Fragstats allowed to identify the principal parameters to explain the fragmentation process and of the land use spatial and temporal pattern related to forest and capoeira use classes, besides a compromising gradient of the environmental quality of the watershed. The Lajeado Perau and Rio Pardo were considered the minus, and the Lajeado Castelinho and Lajeado Mico the more committed watershed. The cartographic database represents an essential contribution for the watershed environmental management proposal in the perspective of the regional sustainbility.