Riverine Water Quality Models

Riverine water quality models have been used for main-stem and tributary streams and waterways to assess water quality impacts resulting from human activities. Two models are used at WES: QUAL2E, a steady-state, one-dimensional (longitudinal) stream water quality model developed by EPA; and CE-QUAL-RIV1, a one-dimensional, dynamic flow and water quality model for streams developed through WES. Both models have been applied for a wide variety of conditions, such as regulated streams (i.e., navigable waterways with multiple locks and dams and stream re-regulation), reservoir tailwaters, and large rivers (e.g., the Ohio and Missouri). CE-QUAL-RIV1 was developed for highly unsteady flow conditions, such as storm water flows and streams below peaking hydropower dams. The QUAL2E model is used for studies where steady, or slowly varying, flow can be assumed. In cooperation with other WES laboratories, two-dimensional (depth-averaged) riverine/waterway model studies can also be conducted. This requires application of a two-dimensional (2D) hydrodynamic model and coupling output to a 2D water quality model, such as CE-QUAL-ICM run in a 2D mode. This approach has been used for large, shallow waterways, harbors, and embayments.