Effluent Mixing Zone in a Shallow River

A case study was made for a low momentum cooling water plume discharged from the shore into a very shallow river. The maximum width, maximum length, and enclosed surface area of a mixing zone were determined as a function of dilution ratio, discharge to river flow ratio and weather parameters. Theoretical results and extensive field data were reduced to dimensionless relationships given in either graphical or analytical form. From these relationships, appropriate discharge rates and discharge temperatures can be extracted easily for a given riverflow and for specified temperature constraints imposed, e.g., in midstream. It is advocated that similar site-specific information and operational aides can be prepared for any outfall and are necessary to assess the all-time impact of an effluent on a water body.