Transverse mixing of pollutants in streams: a review

Spilling or release of foreign particles in the flowing water is considered as pollution of water, and due to the inherent property of water to dissolve the substance, the particulate is well mixed in water. To monitor the extent of pollution in a stream it is essential to know how the pollutants mix in the river. It is observed that vertical mixing of pollutants is a very rapid process in the vertical directions and longitudinal mixing occurs very far from source of pollutant, which is generally out of reach of observations. Thus intermediate or transverse mixing zone is considered very important for water quality modeling. This paper is an attempt to summarize the phenomenon behind pollutant transport, reduction of three-dimensional advection-dispersion equation to two-dimensional equation, and factors causing and affecting transverse mixing of pollutants.