Stochastic modeling to forecast hydrological variables under changing climatic conditions is essential for water resource management and adaptation planning. This study explores the applicability of stochastic models, specifically SARIMA and SARIMAX, to forecast monthly average river discharge in a sub-basin of the Paranaíba River near Patos de Minas, MG, Brazil. The Paranaíba River is a vital water source for the Alto Paranaíba region, serving industrial supply, drinking water effluent dilution for urban communities, agriculture, fishing, and tourism. The study evaluates the performance of SARIMA and SARIMAX models in long-term discharge modeling and forecasting, demonstrating the SARIMAX model’s superior performance in various metrics, including the Nash–Sutcliffe coefficient (NSE), the root mean square error (RMSE), and the mean absolute percentage error (MAPE). The inclusion of precipitation as a regressor variable considerably improves the forecasting accuracy, and can be attributed to the multivariate structure of the SARIMAX model. While stochastic models like SARIMAX offer valuable decision-making tools for water resource management, the study underscores the significance of employing long-term time series encompassing flood and drought periods and including model uncertainty analysis to enhance the robustness of forecasts. In this study, the SARIMAX model provides a better fit for extreme values, overestimating peaks by around 11.6% and troughs by about 5.0%, compared with the SARIMA model, which tends to underestimate peaks by an average of 6.5% and overestimate troughs by approximately 76.0%. The findings contribute to the literature on water management strategies and mitigating risks associated with extreme hydrological events.

This paper focuses on time-space characterization of drought conditions in the São Francisco River catchment, on the basis of wavelet analysis of Standardized Precipitation Index (SPI) time series. In order to improve SPI estimation, the procedures for regional analysis with L-moments were employed for defining statistically homogeneous regions. The continuous wavelet transform was then utilized for extracting time-frequency information from the resulting SPI time series in a multiresolution framework and for investigating possible teleconnections of these signals with those obtained from samples of the large-scale climate indexes ENSO and PDO. The use of regional frequency analysis with L-moments resulted in improvements in the estimation of SPI time series. It was observed that by aggregating regional information more reliable estimates of low frequency rainfall amounts were obtained. The wavelet analysis of climate indexes suggests that the more extreme dry periods in the study area are observed when the cold phase of both ENSO and the PDO coincides. While not constituting a strict cause effect relationship, it was clear that the more extreme droughts are consistently observed in this situation. However, further investigation is necessary for identifying particularities in rainfall patterns that are not associated to large-scale climate anomalies.

Because it is assumed that the impacts in the natural streamflow regime promoted by Small Hydropower Plants (SHP) are negligible, environmental licensing for such facilities is usually easier. Nonetheless, recent studies have shown that the operation of SHPs may disturb the natural flow conditions, mainly when the plants are placed in a cascade arrangement. In this context, the main objective of this study is investigating the alterations in flows periodic behavior in a system of six hydropower plants, being five of them SHPs. Daily discharge time series were extracted from eight streamflow gauging stations located in the Jauru River catchment, Brazil, whose period-of-record spans from May/2016 to Aug/2017. By using the wavelet transform, dominant cycles along the time series were identified and their coherence in nearby stations was compared. Among the results, one may observe that, from upstream to downstream, the high frequency cycles became more important whereas the low frequency ones have weakened. Additional analyses indicate that such alterations are not directly related to meteorological factors or to the gradual increasing in the catchment’s drainage area in the downstream direction, which suggests that the operation of SHPs may affect the streamflow natural cycles.

RESUMO: O presente trabalho tem como principal objetivo fazer o levantamento das condições dos sistemas prediais hidráulicos e sanitários de escolas públicas da regional norte do município de Cuiabá, Mato Grosso. Para isso, foram realizados estudos de diagnóstico desses sistemas em três diferentes edificações de tipologia educacional. O diagnóstico foi realizado por meio de inspeção visual e registros fotográficos dos ambientes sanitários, além da aplicação de questionário aos usuários das edificações. Como os dados coletados foram observados que os aspectos de maior insatisfação relacionam-se com manifestações patológicas de fácil intervenção e correção, como a falta de higiene, mau cheiro dos ambientes, vazamentos visíveis, entupimentos, mau posicionamento dos bebedouros e empoçamento de água. Nesse contexto, recomenda-se que a administração pública mantenha um programa contínuo de manutenção das escolas, a fim de prevenir ou diminuir essas manifestações. Dessa forma, seriam evitados grandes gastos com problemas de proporções majoradas por descuido e falta de manutenção, além disto, seriam mantidas condições apropriadas de saúde e o bom estado do ambiente educacional dos alunos. A maior contribuição deste trabalho é mostrar a situação em que se encontram os sistemas prediais hidráulicos sanitários das escolas públicas e, também, a identificação de que o bom estado das escolas públicas depende dos cuidados advindos desde a sua concepção até sua utilização pós-ocupação, contando suporte proveniente do governo e gestores, bem como, recursos financeiros que sejam adequados e suficientes para as necessidades de operação e manutenção e ao funcionamento adequado das atividades educacionais no Brasil. This study aims to survey the condition of water supply and drainage facilities of public schools in the northern regional city of Cuiabá, Mato Grosso - Brazil. For this, it was made a plumbing system diagnosis of facilities by visual inspection and photographic records data and a questionnaire to the users of the buildings. In the results, the aspects of greatest dissatisfaction are related to pathological manifestations of easy intervention, such as poor hygiene, bad smell, leaks, clogs, wrong positioning of troughs and puddling of water. In this context, it is recommended that the government keep a maintenance program of the schools in order to prevent or lessen these manifestations. Thus would be avoided more expenses with greater problems through carelessness and especially the health and good condition of the educational environment of students would be preserved. The major contribution of this work is to show the situation of building facilities of public schools and the identification that the good condition of public schools depend on care arising from its projection to the end user, with care from the government, with financial resources that are appropriate and sufficient to the needs of the correct functioning of educational activities in Brazil.

This research aimed to use the reuse of fish farming effluents in school gardens, with the purpose of strengthening practical environmental education. The methodology consisted of the following steps: i) construction of a tomato garden (Solanum lycopersicum L.); ii) analysis of the chlorine-free water supply, the treated effluent from the fish farm and the different dilutions used; and to evaluate the students' experience in the project, observations, satisfaction dialogues and records of the activities carried out were used. The 50% and 100% dilutions demonstrated the best results in plant growth and fruit production. Students learn about science, fish farming and reuse, stimulating interest in research and environmental preservation.