The CE-QUAL-W2 model is a significant tool extensively used in lentic environments to analyze eutrophication and water quality. This systematic review of the CE-QUAL-W2 hydrodynamic model revealed its widespread application in analyzing reservoir eutrophication. A total of 151 relevant papers were identified, of which 38 were selected after rigorous analysis, showcasing studies in environmental sciences and water resources. In 2021, we saw the highest number of publications, with six papers; 2022 achieved the highest number of citations, with 113. The model has been widely used across countries, with Iran leading in the number of publications, followed by China and Brazil. The standard combination of CE-QUAL-W2 with the SWAT model reflects its effectiveness in complex watershed studies. CE-QUAL-W2 has demonstrated the ability to predict future environmental conditions and diagnose environmental extremes, and it can calculate various hydrodynamic and water quality parameters. Its increasing use in high-impact scientific journals underscores its global relevance and particular promise for Brazilian aquatic environment studies due to its efficiency and accessibility. With its significant potential, this model is poised to enhance the understanding and management of water resources, contributing to environmental sustainability and inspiring optimism for future applications on a global scale.

The fragmentation of Brazilian rivers due to the construction of hydroelectric dams has altered aquatic ecosystems, resulting in the accumulation of residues in sediments. This study evaluated the cytotoxicity and genotoxicity of water and sediments from the Cana Brava reservoir, located in the Tocantins-Araguaia basin in the Cerrado biome, using the Allium cepa test. Sampling points were situated in the Cana Brava reservoir near two tributaries, the Bonito River and the Varjão Stream, areas susceptible to contaminant input due to proximity to urban areas. Physicochemical parameters, metals through atomic absorption spectrometry, toxicity, and analyses of bioindicators such as microalgae and macrophytes were assessed. Near the Varjão Stream, algal richness was higher, with the presence of Chara rusbyana, which indicates good water quality. Near the Bonito River, pollution-indicating microalgae such as Euglena sp., Nitzschia sp., and Oscillatoria sp. were identified, along with a prevalence of Salvinia auriculata, favored by nutrient availability. Cytogenetic tests revealed that sediments, especially from the site near the Varjão Stream, caused chromosomal abnormalities and cytogenotoxic effects, with an increase observed after 72 hours. Principal components analysis showed that phosphorus and potassium in the sediment from the site near the Bonito River correlated with cellular alterations at 48 hours, while sediments near the Varjão Stream resulted in a higher frequency of cytogenetic alterations at 72 hours. These results highlight local impacts on water quality and biological diversity, recommending continuous monitoring to mitigate the adverse effects of pollution in the Cana Brava reservoir.

Este trabalho teve o objetivo de implementar, calibrar e validar os modelos conceituais de chuva-vazão Tank Model e HyMOD no intuito de simular a vazão na bacia hidrográfica do Rio das Almas no estado de Goiás. O conjunto de dados utilizados abrangeu uma série de 32 anos de dados hidrológicos diários (01 de agosto de 1982 a 31 de julho de 2017), os anos de 1995, 1996 e 1997 foram excluídos por não apresentarem dados completos de vazão. Os dados de precipitação foram obtidos através dos registros das três estações pluviométricas localizadas na área da bacia e o volume de precipitação média diária foi calculada por meio do Método de Thiessen. A otimização dos parâmetros dos modelos Tank Model e HyMOD foi realizada por meio de dois métodos automáticos de calibração utilizando algoritmos da ferramenta Solver do Excel: Programação não-linear do Gradiente Reduzido Generalizado (GRG) e o método Evolutionary. Tais algoritmos foram aplicados considerando dados de vazão e precipitação em escala diário e mensal. Essas escalas foram utilizadas com intuito de compara os resultados obtidos. A análise de desempenho foi realizada com o coeficiente de eficiência Nash-Sutcliffe (NSE). Ambos os modelos puderam ser calibrados de maneira satisfatória para os dados de entrada da bacia em estudo e apresentaram melhor desempenho na escala mensal. Entretanto, o HyMOD apresentou melhor ajuste na calibração (NSE: 0,80) e maior flexibilidade no ajuste dos coeficientes NSE e uma representação gráfica mais precisa quando comparada ao Tank Model (NSE: 0,75).Palavras – chave: Modelagem Hidrológica, calibração, validação, HyMOD, Tank Model. Calibration and validation of hydrological models for a hydrographic basin in the state of Goiás. ABSTRACTThis work aimed to implement, calibrate, and validate the conceptual rain-runoff models Tank Model and HyMOD to simulate the flow in the Rio das Almas hydrographic basin in the state of Goiás. The dataset used covered a series of 32 years of daily hydrological data (August 1, 1982, to July 31, 2017), the years 1995, 1996 and 1997 were excluded for not presenting complete flow data. Precipitation data were obtained from the records of the three pluviometric stations located in the basin area and the daily mean precipitation volume was calculated using the Thiessen Method. The optimization of the parameters of the Tank Model and HyMOD models was performed using two automatic calibration methods using algorithms from the Excel Solver tool: Nonlinear Generalized Reduced Gradient (GRG) programming and the Evolutionary method. Such algorithms were applied considering flow and precipitation data on a daily and monthly scale. These scales were used to compare the results obtained. The performance analysis was performed with the Nash-Sutcliffe efficiency coefficient (NSE). Both models could be satisfactorily calibrated for the input data of the basin under study and presented better performance in the monthly scale. However, the HyMOD showed better calibration adjustment (NSE: 0.80) and greater flexibility in the adjustment of NSE coefficients and a more accurate graphical representation when compared to the Tank Model (NSE: 0.75).Keywords: Hydrological Modeling, Calibration, Validation, HyMOD, Tank Model.