MIXING OF POLLUTANTS IN RIVERS

Abstract

Mixing is understood as a basically physical process which is controlled by the properties of the substances involved in it. The various mixing processes in nature can broadly be grouped according to the substances (solid, fluid, gaseous). As a consequence of human activities growing quantities of pollutants can be observed which alerted international organizations. The investigation of the mixing on physical models is rather complicated due to the fact that similarity can only be achieved by using undistorted models. Reliable dispersion coefficients can be expected from the field studies. Methodology and results are demonstrated by measurements over a long Danube reach and within a city. Importance of field studies and the need of further investigations are underlined and the expected results of potential field surveys are summarized. Suggestions for international coilaborations are submitted.