Rapid Calculation of Oxygen in Streams: Approximate Delta Method

• Published in: Journal of environmental engineering (New York, N.Y.) Vol. 131; no. 3; pp. 336 - 342
• Main Authors: McBride, Graham B, Chapra, Steven C
• Format: Journal Article
• Language: English
• Published: Reston, VA American Society of Civil Engineers 01.03.2005
• Subjects: Applied sciences; Continental surface waters; Exact sciences and technology; Freshwater; Natural water pollution; Pollution; TECHNICAL PAPERS; Water treatment and pollution; USA; Aeration; Decision support systems; New Zealand; Decision support system; Surface water; Reaeration; Stream; Mathematical models; Rivers; Dissolved oxygen; Streams
• ISSN: 0733-9372; 1943-7870
• DOI: 10.1061/(ASCE)0733-9372(2005)131:3(336)

The “approximate delta method” is a simple procedure for simultaneous calculation of the stream reaeration coefficient, primary production rate, and respiration rate from a single-station stream diurnal profile of dissolved oxygen (DO). It approximates the exact graphs of results for the “delta method” reported in 1991 by Chapra and Di Toro by means of simple logistic curve-fitting approximations. The necessity of reading graphs or of obtaining numerical solutions is thereby avoided, so making it suitable for inclusion in a decision support system, particularly for streams reaeration coefficients less than 10 day−1 and for moderate photoperiods (10–14 h) . Worked examples are given for streams in the USA and in New Zealand. Results are used to show that the constellation of parameters for the three fundamental processes is much more important than their individual values in calculating diurnal DO profiles. Independent measurement of the reaeration coefficient enhances the utility of the method, by enabling separate calculation of production and respiration rates.