Monitoring flow in channels is difficult, expensive, and potentially dangerous; hence, alternatives minimizing these factors are sought and indirect methods to measure the flow based on water-level information, among others, are employed. Ultrasonic sensors along with Arduino are widely used to monitor levels in reservoirs; however, the accuracy of this method in turbulent flow regimes has not been evaluated. Therefore, in this study, we evaluated the level of open channel flows using a combination of Arduino and ultrasonic sensors whilst considering turbulence. Additionally, we statistically compared the simultaneous measurements of levels obtained using five ultrasonic sensors with those of five rulers filmed individually along an artificial channel, for four permanent and two transient regimes. The results showed that the errors in measurements increased with increasing turbulence. These errors were within the range of hydraulic measurements (<0.020 m), indicating that the procedure is valid for experienced conditions. Therefore, the combination of Arduino and ultrasonic sensors is a technically and economically viable alternative. However, calibrating and validating the sensors for distances greater than 0.400 m should be performed with care because the bench tests performed in static conditions were limitedly accurate in measuring distances greater than 0.200 m.

Accurate estimation of precipitation patterns is essential for the modeling of hydrological systems and for the planning and management of water resources. However, rainfall time series, as obtained from traditional rain gauges, are frequently corrupted by missing values that might hinder frequency analysis, hydrological and environmental modeling, and meteorological drought monitoring. In this paper, we evaluated three techniques for filling missing values at daily and monthly time scales, namely, simple linear regression, multiple linear regression, and the direct imputation of satellite retrievals from the Global Precipitation Measurement (GPM) mission, in rainfall gauging stations located in the Brazilian midwestern region. Our results indicated that, despite the relatively low predictive skills of the models at the daily scale, the satellite retrievals provided moderately more accurate estimates, with better representations of the temporal dynamics of the dry and wet states and of the largest observed rainfall events in most testing sites in comparison to the statistical models. At the monthly scale, the performance of the three methods was similar, but the regression-based models were unable to reproduce the seasonal characteristics of the precipitation records, which, at least to some extent, were circumvented by the satellite products. As such, the satellite retrievals might comprise a useful alternative for dealing with missing values in rainfall time series, especially in those regions with complex spatial precipitation patterns.

Quantifying the consequences of runoff and degree of infiltration in an urban basin allows the assessment of channel drainage patterns, the occurrence of floods and erosion. The objective of this study was to study the hydromorphology of the urban watershed of the Botafogo Stream, aiming to quantify the physical and morphological parameters that interfere in its hydrological behavior. The methodology used in the study was the use of numerical equations, in addition to the raster and vector data generated in the GIS program, favoring the investigation of the parameters of linearity, area, length and hypsometry of the basin, revealing the behavior of the physiography of the river basin and indicating the morphological indices that interfere in its hydrological activity. Floods in the Botafogo Stream have been frequent due to the altimetric gradient (143 m) of the water body that is born at quota 844 and flows at an altitude of 701 m in relation to the level of the sea, indicating a slight slope that contributes to the rapid concentration of rainwater in the Botafogo Stream and its tributaries. The Botafogo River Basin is poorly drained (0.58 km ^-1) suggesting, therefore, that the occurrence of floods is related to the relief.

Precipitation products derived from satellites have emerged as a promising approach for obtaining precipitation estimates, enabling accurate long-term observations and describing the water cycle dynamics from a global scale to a local scale. The quality of these products has improved significantly in the last decades, especially with the emergence of TRMM missions and its successor GPM. The objective of this study was to evaluate the daily, monthly and annual precipitation estimates provided by IMERG version 05 of the GPM, with the data observed by the rainfall stations of the Brazilian Agency of Water and Sanitation (ANA) in the basins of the Brazilian midwest. In order to compare the data, the spatialization of the data of the rainfall stations was performed by means of the ordinary kriging technique, interpolating the data for grids of 0.1° × 0.1° that correspond to the specialized grids of the GPM satellite. The data were evaluated quantitatively by means of statistical metrics. The GPM satellite precipitation product performed relatively well on a daily scale for regions with smooth topography, and was able to describe the rainfall regime on larger time scales, regardless of the terrain conditions. However, the satellite retrievals were unable to reproduce rainfall extremes in virtually all situations, which may limit their application in frequency analyses.

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.

O estudo teve por objetivo a realização da calibração do modelo hidrológico Storm Water Management Model (SWMM) para a Bacia Hidrográfica do Arroio Cancela, localizada em Santa Maria, Rio Grande do Sul, utilizando o algoritmo evolucionário multiobjetivo R-NSGA. Para tanto, foram realizadas modificações na estrutura do SWMM, de modo que permitisse seu acoplamento como Evolucionary Reference Point Based Non-Dominated Sorting Genetic Algorithm (R-NSGA) em ambiente de programação MATLAB. As funções objetivo utilizadas foram o Coeficiente de Eficiência de Nash-Sutcliffe (COE), o Erro da Vazão de Pico (EQP) e o Erro do Volume Escoado (EVOL) aplicadas simultaneamente na calibração do modelo. Foi proposto um método para determinação da maior compatibilidade de modo a elencar as melhores soluções. Os resultados dos parâmetros calibrados do SWMM foram próximos aos valores físicos da bacia, com exceção dos valores relativos à equação de Horton. As soluções de maior compatibilidade apresentam um melhor comportamento para os eventos de validação, evidenciando a importância da otimização multiobjetivo.