Modelagem da estrutura térmica e estudo da cor de um lago raso

Abstract

The mathematical modeling is a tool for ecological studies that has been applied to management of aquatic ecosystems with focus on physical, chemical and biological compartments. This thesis aimed to apply a three-dimensional hydrodynamic model (Elcom) in Manacás Lake, with the purpose to obtain a realistic representation of the thermal reservoir structure. When calibrated, the Elcom is an efficient methodology that can be applied for rapid analysis of the water column mixing and stratification processes. It is known that the movement of water influences the nutrient dynamics and biological communities, as well as resuspension of sediment, which acts as a source of organic and inorganic material into the system. This study also aimed to relate the physical and climatic influences on the biogeochemistry and color of the water. Our data demonstrated that Elcom has been satisfactorily represented on the water surface (epilimnion), only with local climatic configuration. However, this result was not obtained in the intermediate region (metalimnion) and in the bottom (hypolimnion). Thus, it was important to understand the forces that influence the water movements, which was associated with predominant winds (NE-E) and velocity of 7.8 m s-1; the rain acted indirectly and significantly increasing the inflow and promoting the runoff. It was observed that during rainy days in December, the lake remained mixed, with high levels of turbidity and suspended solids, which indirectly influence the true color of water. Our initial hypothesis was overthrow failed, because the Dissolved Organic Carbon (COD) did not affect the color. Overall, Manacás Lake is not limited by nitrogen and phosphorus, it presented chemical stratification, has neutral pH and high concentrations of Total Iron (TI) on the bottom, which was related to the FOS, since higher values of phosphate ( FOS), were present when the TI was lower. This work has the prospect of future application of biogeochemical data in ecological model (Caedym) and to calibrate it in Manacás Lake. Thus, the coupled modeling Elcom - Caedym can be envisioned for future studies.