Dissolved oxygen depletion in the Tarawera River / J.C. Rutherford, R.J. Wilcock, Glenys F. Croker

The Water Quality Centre was asked to assist in the preparation of a Water Management Plan for the Tarawera river by carrying out field and mathematical modelling work aimed at quantifying the amount of effluent which can be discharged to the river without causing excessive oxygen depletion. Field studies were undertaken under conditions of steady BOD loading, to measure : river dissolved oxygen concentrations, the reaeration rate, the rate of uptake of oxygen in samples of river water isolated from the bed, and the rate of uptake of oxygen in the sediments. From these measurements an oxygen budget was calculated and the principle mechanisms of oxygen depletion elucidated.