Daniel Henrique Marco Detzel

Nonstationarity in determining flow-duration curves aiming water resources permits

Anthropogenic activities in the watersheds are responsible for land use changes, thus interfering in its rivers flows regimes. Consequently, changes occur in the hydrological series statistical moments, a condition known as nonstationarity. The use of a nonstationary time series can cause relevant errors, misleading and biasing the ongoing analyses. In this manner, this paper evaluates the possible effects of nonstationarity over water availability for water resources permits in six Brazilian gauges, considering the Q95% as reference. Median and seasonal flow-duration curves are employed in two distinct periods, before and after 1969, for all the series. Results suggested that Q95% increased in four gauges and reduced in the remainder two. Moreover, important changes were observed in intermediate flow-durations, suggesting that the variations are not limited to the series extreme values

Não Estacionariedade na Construção de Curvas de Permanência com Vistas à Outorga de Recursos Hídricos

Anthropogenic activities in the watersheds are responsible for land use changes, thus interfering in its rivers flows regimes. Consequently, changes occur in the hydrological series statistical moments, a condition known as nonstationarity. The use of a nonstationary time series can cause relevant errors, misleading and biasing the ongoing analyses. In this manner, this paper evaluates the possible effects of nonstationarity over water availability for water resources permits in six Brazilian gauges, considering the Q95% as reference. Median and seasonal flow-duration curves are employed in two distinct periods, before and after 1969, for all the series. Results suggested that Q95% increased in four gauges and reduced in the remainder two. Moreover, important changes were observed in intermediate flow-durations, suggesting that the variations are not limited to the series extreme values

Otimização na Contratação de Energia: Uma Análise de Sensibilidade Sobre a Demanda

A legislacao vigente no setor eletrico brasileiro, impoe que as distribuidoras contratem energia atraves de leiloes, sendo obrigadas a atender a totalidade de suas demandas, e em caso de descumprimento sao penalizadas financeiramente. [...]

Statistical validity of water quality time series in urban watersheds

The water resources quality continuous monitoring is a complex activity. It generates extensive databases with time series of many variables and monitoring points that require the application of statistical methods for the information extraction. The application of statistical methods for frequency analysis of time series is linked to attending of the basic assumptions of randomness, homogeneity, independence, and stationarity. However, despite its importance, the verification of these assumptions in water quality literature is unusual. Therefore, the present study tests the Upper Iguaçu basin water quality time series against the mentioned hypotheses. Rejection was observed in 15%, 26%, 51% e 31% for randomness, homogeneity, independence, and stationarity, respectively. The results evidenced the strong relation between monitoring strategy, data assessment and meeting of basic statistical assumptions for the analysis of water quality time series. Even with the existence of possible solutions for addressing those issues, the standard monitoring strategies, with irregular frequencies and lack of representativeness in relation to other periods, beyond commercial, act as an obstacle to their implementation.

Nonstationarity in building flow duration curves aiming at obtaining water resource permits

Anthropogenic activities in the watersheds are responsible for land use changes, thus interfering in its rivers flows regimes. Consequently, changes occur in the hydrological series statistical moments, a condition known as nonstationarity. The use of a nonstationary time series can cause relevant errors, misleading and biasing the ongoing analyses. In this manner, this paper evaluates the possible effects of nonstationarity over water availability for water resources permits in six Brazilian gauges, considering the Q95% as reference. Median and seasonal flow-duration curves are employed in two distinct periods, before and after 1969, for all the series. Results suggested that Q95% increased in four gauges and reduced in the remainder two. Moreover, important changes were observed in intermediate flow-durations, suggesting that the variations are not limited to the series extreme values

Comparison between Deseasonalized Models for Monthly Streamflow Generation in a Hurst–Kolmogorov Process Framework

AbstractThe Hurst–Kolmogorov (HK) behavior in geophysical series is the product of fluctuations occurring simultaneously at several time scales. In streamflow time series, the clustering of similar events characterizes this behavior and brings forth the peculiarly persistent structure of such series. Because the Hurst exponent expresses the intensity of the HK behavior in time series, it is essential to preserve it in modeling hydrological series. This paper addresses an approach for multisite monthly streamflow generation in a HK framework. A deseasonalized symmetric moving average (SMAD) model is proposed, in which the seasonal components are removed from the streamflow series prior to their submission to the model. A case study applied at six gauging stations in the Iguazu River Basin, southern Brazil, is presented. SMAD synthetic series are compared with a multisite contemporaneous autoregressive integrated moving average (CARIMA) model. The results show that both models exhibited similar performance ...

Ferramenta de apoio à determinação de concentração de PCBs em óleo mineral isolante

A maioria das concessionarias de energia eletrica possui equipamentos com isolamento a base de oleo mineral, sujeitos a contaminacao por compostos do tipo bifenilas policloradas (PCBs), altamente poluentes. No Brasil, as restricoes de uso das PCBs foram implementadas pela Portaria Interministerial 19, de 2 de janeiro de 1981, que proibiu a fabricacao, comercializacao e uso das PCBs em todo territorio nacional. A identificacao e quantificacao dessas substâncias em oleo mineral, como e realizado atualmente, e baseada no conhecimento do tecnico, o que torna o processo subjetivo. A pesquisa desenvolvida e produto do projeto de P&D desenvolvido pelo LACTEC em conjunto com a CTEEP – Companhia de Transmissao de Energia Eletrica Paulista e tem como objetivo o desenvolvimento de uma nova metodologia para quantificacao do teor de PCBs nas amostras de oleo mineral, baseada em calculos numericos, visando reduzir a subjetividade desta quantificacao.