Impact of rain runoff on oxygen in an urban river

The river Harrestrup is an urban river in the western region of Greater Copenhagen, Denmark. It has been subject to intensive on-line investigation of the oxygen regime in the river, both during dry weather and during rain runoff from the neighbouring urban areas. The oxygen fluctuations have been modelled both deterministicly and statisticly. The statistical features turned out to be as important as the deterministic. The final evaluation of the performance was done by comparison of extreme statistics as measured over one year with results generated by the calibrated deterministic model, superimposed with calibrated statistical properties. The result was a clear demonstration of non-compliance with oxygen standards both during dry weather and during wet weather. The technical measures are river restoration to decrease daily oxygen fluctuations and construction of detention basins in the urban catchments to decrease the impact of rain runoff. Copyright (C) 1996 IAWQ.