EPA Rates Manual

Reviewing and researching nutrient-related rates, constants, and kinetics in four water quality model frameworks.

2015 - Present
Athens, Georgia
Environmental Protection Agency's Office of Research and Development

The widely used 1985 Second Edition of Rates, Constants, and Kinetics Formulations in Surface Water Quality Modeling (the Rates Manual) provides information on kinetic formulations for surface-water quality modeling and associated rate constants and coefficients. As a result of advancements in water quality modeling over the last 3 decades, new and updated formulations are not documented in the 1985 Second Edition. Furthermore, recent modeling and water quality process studies have provided additional information on suitable values of rate constants and coefficients for model applications. RESPEC participated as one of the model experts that performed a literature review reflecting the latest state-of-the-science information on surface water quality modeling and modeling parameters, which constituted the beginning effort to compile content for updating the existing Rates Manual.

The Cadmus Group, Inc., in collaboration with HDR, Inc. (HDR), RESPEC, Dr. Steven Chapra of Tufts University, and Dr. James Martin of Mississippi State University, compiled and reviewed literature relevant to four water quality models that are commonly used for water quality management planning and Total Maximum Daily Load (TMDLs) development: (1) WASP , (2) CE-QUAL-W2, (3) HSPF, and (4) QUAL2K (and QUAL2Kw). The compiled literature consists of model documentation, model application studies, and studies that involve collecting field or laboratory data on water quality processes that are simulated in each model. To report the Year 1 progress, the Cadmus team prepared a document that included a description of recent developments in dissolved oxygen, nutrient, and algae modeling in WASP, CE-QUAL-W2, HSPF, and QUAL2K (and QUAL2Kw ). These groups of parameters have been referred to as Batch 1 parameters because they are the first of a multiphase effort to gather rates, constants, and kinetic parameters. Future efforts will focus on other parameter groups, such as pH, temperature, macrophytes, and bacteria. The Year 1 Report also includes a discussion of the literature selection and reviews steps that were taken to assess the applicability and thoroughness of model investigations.

The information presented in the Year 1 Report describes an assessment of the literature related to the application of the four models and includes information on the geographic and environmental range of modeling efforts as well as any gaps in location, modeled constituents, and environmental conditions. This report is designed to describe each model (with a focus on updates since 1985) and the results of the literature review. A second main objective of this project is to extract rate, constant, and kinetic parameters from relevant literature sources and present the information in a searchable database for model practitioners. Because the main focus of this effort was to identify and evaluate post-1985 model applications, the majority of the studies are applications of each model to a water quality concern (often TMDL development). The parameter value tables that constitute the other portion of this project contain study-specific metadata for each model application, including study location, geographic applicability, environmental conditions, purpose and model use, calibration period, and an input data sampling plan.


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