Utilização de geotecnologias para avaliação de características ambientais em ecossistemas aquáticos

Abstract

Reservoirs are artificial complex systems influenced by watershed characteristics, and subjected to anthropogenic pressures suffer imbalances in the dynamics of their physical-chemical and hydrobiological processes, leading to degradation states. Understanding the interactions between the terrestrial system (watershed) and the aquatic system (reservoir) becomes crucial in the adoption of strategies for qualitative and quantitative management of water resources. The analysis of aquatic ecosystems using expedited methods in combination with in situ data acquisition allows for greater speed and coverage of information processing. In Funil-RJ reservoir the constant input of organic pollutants from its watershed promotes the degradation of water quality, with the establishment of eutrophic conditions and the emergence of frequent algal blooms. In this context, this dissertation is divided into three chapters developed in accordance with the following objectives: 1) to evaluate the factors of human pressure on the trophic status of the Funil reservoir through GIS modeling; 2) analyze their limnological characteristics through the collection and analysis of water quality parameters; and 3) using field and orbital remote sensing techniques to analyze the chlorophyll-a concentration in the water. The results indicated that the potential concentration of nutrients would exceed the limits established in most of the basin, predominantly to the point sources, but with a significant contribution from non-point sources (diffuse). With concerning to the limnological characteristics of Funil reservoir, was verified the predominant occurrence of a supereutrophic state over analyzed period, with a marked gradient upstream (worst condition) to downstream (best condition). The spectral characteristics of the water, both obtained in situ as satellite (MERIS sensor) showed some characteristic features of the presence of phytoplankton in the reservoir, especially in the red and near-infrared regions of the electromagnetic spectrum, indicated by significant correlations between NDVI index and the chlorophyll-a concentrations in the water. We conclude that the high potential for nutrient loading from the watershed affects largely the process of eutrophication in the Funil reservoir and methods that use remote sensing to estimate phytoplankton concentrations may be useful in the study of continental aquatic systems.