Statistical validity of water quality time series in urban watersheds

• Autor(a) principal: Coelho,Marcelo
• Data de Publicação: 2017
• Outros Autores: Fernandes,Cristovão Vicente Scapulatempo, Detzel,Daniel Henrique Marco, Mannich,Michael
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: RBRH (Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S2318-03312017000100247
• topic: Homogeneity; Independence; Randomness; Stationarity; Monitoring strategies

ABSTRACT 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.