Temperature dependence of stream aeration coefficients and the effect of water turbulence: A critical review

• Published in: Water research (Oxford) 2013-01, Vol.47 (1), p.1-15
• Main Authors: Demars, B.O.L., Manson, J.R.
• Format: Article
• Language: English
• Subjects: aeration; Aerodynamics; Air Movements; bubbles; case studies; Chemistry; Computational fluid dynamics; Dual tracer gas studies; equations; Exact sciences and technology; Fluid flow; Gas transfer coefficient; Gas-liquid interface and liquid-liquid interface; General and physical chemistry; Green house gas emission; greenhouse gas emissions; Mathematical models; Models, Theoretical; Oxygen; Oxygen - chemistry; photosynthesis; Rivers - chemistry; Streams; Surface physical chemistry; surface water; Temperature; Temperature dependence; Turbulence; Turbulent flow; weirs; Whole stream metabolism
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2012.09.054

The gas transfer velocity (KL) and related gas transfer coefficient (k2 = KLA/V, with A, area and V, volume) at the air–water interface are critical parameters in all gas flux studies such as green house gas emission, whole stream metabolism or industrial processes. So far, there is no theoretical model able to provide accurate estimation of gas transfer in streams. Hence, reaeration is often estimated with empirical equations. The gas transfer velocity need then to be corrected with a temperature coefficient θ = 1.0241. Yet several studies have long reported variation in θ with temperature and ‘turbulence’ of water (i.e. θ is not a constant). Here we re-investigate thoroughly a key theoretical model (Dobbins model) in detail after discovering important discrepancies. We then compare it with other theoretical models derived from a wide range of hydraulic behaviours (rigid to free continuous surface water, wave and waterfalls with bubbles). The results of the Dobbins model were found to hold, at least theoretically in the light of recent advances in hydraulics, although the more comprehensive results in this study highlighted a higher degree of complexity in θ’s behaviour. According to the Dobbins model, the temperature coefficient θ, could vary from 1.005 to 1.042 within a temperature range of 0–35 °C and wide range of gas transfer velocities, i.e. ‘turbulence’ condition (0.005