Three related studies are described which provide the means to quantify the pollutional and hydraulic effects on flowing streams caused by stormwater runoff. Mathematical stream models were developed to simulate the biological, physical, chemical, and hydraulic reactions which occur in a stream. Relationships take the form of differential equations with the two independent variables of time and distance. The differential equations can be solved directly by means of calculus or by digital computer using numerical methods. The solution would be the concentration of species of pollutional interest, such as BOD and dissolved oxygen, within the stream as a function of distance and time. The solution can be steady-state or transient. The purpose of this report is to show how the solution can be found for the case where the pollution loading is a transient, especially as it applies to the stormwater overflow.

Includes bibliographical references at chapter ends. August 1978.

Introduction -- Summary and conclusions -- Recommendations -- Stormwater overflow pollution stream model (SWOPS) -- Stormwater overflow hydraulic stream model (SWOHS) -- Effect of stormwater on stream dissolved oxygen. Three related studies are described that provide the means to quantify the pollutional and hydraulic effects on flowing streams caused by stormwater runoff. Mathematical stream models were developed to simulate the biological, physical, chemical, and hydraulic reactions that occur in a stream. Relationships take the form of differential equations with the two independent variables of time and distance. The differential equations can be solved directly by means of calculus or by digital computer using numerical methods. The solution would be the concentration of species of pollutional interest, such as BOD and dissolved oxygen, within the stream as a function of distance and time. The solution can be steady-state or transient. There is sufficient information presently available for finding steady-state solutions. However, when the pollution loads and/or the initial conditions for the flowing stream vary with time, the problem becomes much more difficult, and the technology for handling the transient situation has not been adequately developed. The purpose of this report is to show how the solution can be found for the case where the pollution loading is a transient, especially as it applies to stormwater overflow.