Streamflow measurement by salinity dilution method

Abstract

Streamflow measurement often requires a clearly structured measurement reach. Velocity distribution can then be measured using a current meter or by constructing a hydraulic section control (weirs or flumes). However, in turbulent hilly streams such methods are difficult to implement. This paper presents a measuring method suitable for a spot flow gauging in natural streamflows. It is based on the measurement of a tracer concentration (usually common table salt). The method enables accurate flow measurement without determining the cross-section area. The only condition that has to be fulfilled is the uniform mixing of a tracer across the downstream measurement section. The paper describes the theoretical basis and procedure for tracer concentration measuring. The results of the method implementation are presented as well as the tutorial carried out by the students of the Civil Engineering Faculty in Belgrade. Finally, suitability of the method in different flow conditions is commented.

Merenje protoka u otvorenim tokovima najčešće zahteva postojanje jasno uređene merne deonice. Kod brdskih neuređenih bujičnih tokova, u uslovima kada nije potrebno kontinualno merenje protoka i kada se ne zna tačan proticajni presek, merenje protoka je moguće obaviti metodom zasnovanom na merenju koncentracije trasera (obično kuhinjske soli). Jedini uslov koji se mora zadovoljiti je da postoji dobro mešanje trasera u vodi po poprečnom preseku. U radu se daje osnovna teorijska postavka, način merenja koncentracije trasera, rezultati nekoliko izvedenih merenja kao i prikaz vežbe koju izvode studenti na Građevinskom fakultetu u Beogradu. Na kraju rada se daju i komentari o primenljivosti metode u različitim uslovima.