Edner Baumhardt ,Elisandra Maziero,Marília Ferreira Tamiosso,Jussara Cabral Cruz,João Francisco Horn, UNIVERSIDADE FEDERAL DE SANTA MARIA, HIDRÁULICA E SANEAMENTO, EDNERB@GMAIL.COM
ABSTRACT
The influence of barometric-tide in the level data to monitoring small basins In all points of earht’s surface, the atmospheric pressures varies regularly, presenting a double daily fluctuation with peaks at 10 a.m. and 10 p. m., the called barometric-tide. Some sensors used to level monitoring in watercourses take values of atmospheric pressure to determinate the water column. Then, the barometric-tide have instilled a systematic error over the observed flow data (level x triangular weir), when instrument collectors would be used as the pressure transducers. The treatment was based on historical data of 365 days of a small basins forested with Eucalyptus in the city of Rosário do Sul – RS. A statistical tool in spreadsheet called moving average was applied, in which average blocks of 8, 12 and 24 hours were tested. Calculating the maximum possible error of flow for rainless period to a proposed hydraulic structure and applying a moving average in every 24 hours, it was obtained a difference of 0.02 L/s to a field watershed and a value of 0,02 L/s to a forested watershed, to more or to less.
Key words: monitoring, data series, barometric interferences