Estudo biofísico, temporal e análise da vulnerabilidade natural à erosão dos solos no município de Manacapuru, Amazonas

Abstract

This research aimed to conduct a biophysical analysis of multitemporal and natural vulnerability to soil erosion in the municipality of Manacapuru, using tools geotecnológicas. The methodological procedure consisted of four phases. The first refers to the structuring and updating the cartographic basis for characterization of the biophysical aspects of the study area. The second phase consisted of multitemporal analysis of satellite images Landsat Thematic Mapper in order to identify changes in land cover and land use for the years 1997, 2003 and 2011. The third phase analysis was performed, cross data to generate the map of vulnerability to natural erosion of soils. In the fourth and final preparation of thematic maps. SPRING is used for handling the database. Supervised classification was performed using the region growing algorithm, Bhattacharya, wherein the input parameters to set the thresholds of similarity and the area segmentation process, were in 20 and 20, respectively. Sequentially, the images were classified using the algorithm in the following uses and land cover: Forest, Secondary Forest, Bare Soil, Water and Crops. The map of vulnerability to soil erosion was obtained by performing the crossover maps of geology, geomorphology, pedology, vegetation / land use and rainfall intensity, through analysis in Spatial Language for Algebraic GIS (LEGAL). In this context, this study allowed us to assess the vulnerability to loss of soil landscape units of the municipality of Manacapuru through a GIS with digital cartographic databases provided by Amazon Protection System (SIPAM), and rainfall data obtained from the National Water Agency (ANA). This study was conducted according to the methodology CREPANI et al. (2001) for developing ecological zoning, based on the concept of ecodynamic TRICART (1977). The main results show that the dominant city has altitudes ranging from 0 to 40 m, these areas amount to about 70% of the territory, the slope levels present in their dominance underscores flat and undulated (0-8%) corresponding to 83.91%. It is estimated that the Permanent Preservation Areas should represent 12.5% of the municipal area, and the conflict areas represent 3.4% of misuse. The study revealed that there was a temporal increase in class Bare Soil, about 5.6% in the period 1997-2011 and according to historical occupation, much of the increase is located in areas with easy access. Concerning the vulnerability of soil were identified three classes of vulnerability Moderately stable Moderately stable and / or moderately weak and vulnerable, corresponding to 35.3%, 38.4% and 1% respectively, ranging 1.5 to 2.5 according to the scale of vulnerability of basic territorial unit. These results may serve as support in various research initiatives, territorial planning, economic development and environmental conservation in the region.