10.4122/1.1000001499 Paoletti, A. Sanfilippo, U. Innocenti, I. Influence of advection, dispersion, transient storage and biochemical decay on the propagation of pollutants discharged by wet weather overflows or continuous spills into streams DTU Library, Technical University of Denmark (DTU) 2005 receiving stream pollution propagation advection dispersion transient storage dead zones Politecnico di Milano en Conference presentation 10.4122/1.1000001500 text/xml 1 The paper analyses, under the hypothesis of steady flow in the receiving stream, the relative importance of the physical processes of advection, dispersion, transient storage in dead zones and biochemical decay on the one-dimensional propagation of pollutants, for intermittent spill (like from a sewer overflow in wet weather) or continuous spill (like from a waste water treatment plant outflow), depending on river morphology and biochemical decay rate. Two different reaches, one straight and the other meandering, are exploited as experimental sites, where a number of time of travel surveys allows to calibrate the ADE, OTIS and ADEK models, comparing their performances. Afterwards, the two different reaches are virtually extended up to 20 kilometres, to simulate numerically the propagation of pollutographs. In case of intermittent spill, such a propagation shows that persistence time above a given concentration threshold at progressive distances downstream increases for low concentrations and decreases for high concentrations, as the concentration curve is spreading due to the longitudinal dispersion, especially for the meandering reach. On the contrary, in case of continuous spill, the longitudinal dispersion has a negligible effect on concentration, while dead zones reduces the mean velocity, consequently increasing the translation time and indirectly facilitating the biochemical decay of pollution.