Aspectos geoambientais e climáticos da sub-bacia do rio Guamá no Nordeste Paraense.

Abstract

The sub-basin of the Guamá River (SBGR) is located in the Mesoregion of the Northeast more specifically in the microregion of Guamá, covers 12 municipalities and has presented a relevant economic and social growth. The Guamá River has economic, social and cultural importance for the municipalities of the region, because for it converge all drainage network composed of small tributaries and large tributaries inserted. Thus, the objective of the research was to evaluate the integration of climate, environmental and water variables with the current transformations of land use and occupation in the area of the sub-basin of the Guamá River, in northeastern Pará. Initially, the estimates of precipitation derived from satellites (remote sensing) for the SBGR area were evaluated and the observations provided by the National Water Agency were compared. Then were mapped and evaluated the different uses and land occupations in the SBGR in order to establish environmental vulnerability from the relationship of physical and biotic elements and their ecodynamics. Finally, the dynamics of physical and chemical parameters of the surface water of the Guamá River were evaluated as a function of seasonal and spatial variability. It was concluded that the data provided by remote databases overestimated by 12% and 13% (CHIRPS and GPCC, respectively) the data observed by pluviometers. However, despite the overestimation of rainfall, it was possible to obtain reliable and satisfactory data from the databases by remote sensing. As for land use and occupation, there was a higher amount of area (57%) characterized as exposed soil and ground vegetation, and a lower amount of area (42%) characterized as dense or secondary vegetation cover. Thus, it was noted the occurrence of areas with high environmental vulnerability (northern portion represented by the urban centers of cities like Ourém and São Miguel do Guamá) and very high (southern portion) as a result of land use and occupation associated with anthropic activities. The areas classified as low or very low vulnerability (central and southern portion), less vulnerable to environmental degradation, were associated with the presence of vegetation cover composed of primary and secondary forest, and less human presence. As for the hydrochemical variables of the surface water of the Guamá River, high spatial heterogeneity was observed along the 12 sampling points, the existence of upward and downward trends in the upstream to downstream direction and the influence of the seasonality of the region. Finally, it is a priority that the results of this research promote benefits to the population of the various localities visited and serve as a guiding instrument for public policies aimed at the conservation of natural resources.