Uso integrado de modelagem matemática e sensoriamento remoto para compreensão da hidrodinâmica do reservatório Serra Azul/MG

Abstract

Lakes and reservoirs are extremely important ecosystems due the variety of ecosystem services they offer. The monitoring of their water quality plays a key role in water resources management and water temperature, especially its vertical gradient, is an important driver of biochemical processes in lentic environments. This research aimed at evaluating how coupling remote sensing, hydrodynamic modeling and in situ monitoring can contribute to better understand the dynamics of a tropical reservoir. In this study, in situ and satellite data were used and a one-dimensional mathematical modeling was applied. Radiometric water temperatures were obtained through thermal infrared measurements from the Landsat 5 and Landsat 7 satellites. Atmospheric correction of satellite data was carried out using the Single Channel Generalized Method (SCGM) and its validation was performed using in situ data. The 1D General Lake Model (GLM) was used to simulate the thermal dynamics of the Serra Azul water supply reservoir located in southeast Brazil, from 1982 to 2002. Sensitivity analysis of hydrodynamic model parameters and input variables was conducted and automatic calibration using (1) in situ data, (2) in situ and remote sensing data and (3) remote sensing data was performed. The SCGM provided good results in the retrieval of surface water temperature. Concerning the hydrodynamic model, sensitivity analysis indicated greater sensitivity to changes in inflows and wind speed. According to the hydrodynamic simulations, Serra Azul reservoir has a warm monomictic behavior, typical of tropical reservoirs. The use of remote sensing data for the hydrodynamic model calibration provided accurate surface water temperatures, however, they did not improve the model performance when comparing to in situ water temperature data. This study presents the integration of different tools to assist monitoring and management of water resources. Results point to the advantages of a more complete and systematic monitoring which allows greater control of water quality, especially in water supply reservoirs.