Streeter-phelps equation

From Glossary of Meteorology

Streeter–Phelps equation

A mathematical model of the variation of dissolved oxygen in a stream due to a point load of waste discharge.

The waste discharge can be characterized by biochemical oxygen demand (BOD) or chemical oxygen demand (COD) and its decay coefficient. The natural aeration of the stream is also included. The equation gives the sag in the dissolved oxygen in the water as a function of the distance from the point load.

Streeter, H. W., and E. Phelps 1925. Bulletin 146. U.S. Public Health Service.