Análise geoambiental da bacia do baixo Paraíba, através do SIG e do modelo de heterogeneidade de habitat.

Abstract

The significant changes in land occupation and use in the Baixo Paraíba Basin – BPB were analyzed presenting the differences at the year range from 1975 to 2007, as well as the variation in pluviometric precipitation and average air temperature in that basin. For the analysis of this region, integrated tools based on Geographic Information System (GIS) were used, applying multicriteria techniques and Modeling of Habitat Heterogeneity (MHH). In this context, the study was developed through the use of a satellite image from Landsat 7 ETM + with scene obtained on September 28, 2007 (analyzed by the use of Erdas 8.7 software), SUDENE letters as a cartographic base for the extraction of information about topography, hydrography and land use and occupation in the BPB in 1975. MHH made it possible to explore several scenarios for the basin, such as characteristics of environmental factors, land use and vegetation cover, and to detect the areas of degradation. The multidisciplinary integration of products (digital maps and remote sensing images) served as the basis of a multitemporal study of the basin, which immediately proved to be efficient in the analysis of changes occurring between 1975 and 2007. Images showed deep changes in the basin studied throughout time, due to a strong influence of socio-economic agents, especially those related to the civil construction field. The impacts that occurred in the BPB were mainly caused by the uncontrolled growth of population, especially on the east coast region, just like the great deforestation resulted in reduced forest typical of the region, a fact caused by increased production of farmed shrimp and planting of cane sugar. During El Niño periods, as it had been expected, the presence of negative anomalies of precipitation at BPB was observed, associated to the raising of the temperature in the region analyzed, which led to the conclusion that these metereological elements combined with the inadequate use of basin areas and their proximities resulted in the degradation of the basin itself. Therefore, as long as public policies are not developed to establish the sustainable development of the region, allowing the construction of a strong socio-economic infrastructure to guarantee the continuity in the supplying of food and biological resources to the population just like nowadays, the basin will remain in constant process of degradation.