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Model Report


Last Revision Date: 08/25/2009 View as PDF
General Information Back to Top
Model Abbreviated Name:

Model Extended Name:

Model Overview/Abstract:
NWPCAM brings together large amounts of environmental data and complex hydrologic and water quality modeling techniques into a system whose purpose is to estimate the water quality and economic benefits of water pollution control policies. NWPCAM began as a point source evaluation tool, using relatively simple nonpoint source (NPS) estimates and basic linear modeling kinetics. The current version of NWPCAM has evolved into a large, comprehensive Oracle-based system that incorporates additional nonlinear kinetics to evaluate pollution control policies. The system contains a much more detailed stream network, large land cover databases with NPS loadings estimates, and numerous modeling modules to simulate NPS and point source policy issues.
Model Technical Contact Information:
Dr. Mahesh Podar
U.S. Environmental Protection Agency
Office of Water
Phone: 202-564-5778
Email: podar.mahesh@epa.gov

Dr. John Powers
U.S. Environmental Protection Agency
Office of Water
Phone: 202-564-5776
Email: powers.john@epa.gov

User Information Back to Top
Technical Requirements
Computer Hardware
PC with DVD Reader
Compatible Operating Systems
Windows 2000, NT, XP
Other Software Required to Run the Model
Download Information
Contact John Powers (202-564-5776)
Using the Model
Basic Model Inputs
Definition of Study Area, Including Continental U.S.; Model Coefficients; sensitivity coefficients; Loadings Changes for Scenarios; Model Choice (linear conventionals, linear toxics, Eutro-WASP, Toxi-WASP); Toxic Pollutants to model (if applicable); flow regime (mean annual or mean summer).
Basic Model Outputs
Water Quality Results for a given model run at Reach File Version 3 Reach-level, including pollutant concentrations, flow, velocity, and integrated water quality indicators.
User Support
User's Guide Available?
The NWPCAM 2.1 User Guide

Model Science Back to Top
Problem Identification

Component 1: River Reach File.

NWPCAM Versions 1.5, 1.6, and 2.1 use Reach File Version 3 (RF3).

Component 2: Database Management System Linked to the Reach File.

With RF3 as the central hydrologic construct, NWPCAM links data, such as point source loadings, NPS loadings, and land cover data to the Reach File to support pollution control scenario definitions, models, and analyses of results. Modeling results are incorporated into the databases to support subsequent modeling components.

Component 3: Models.

NWPCAM utilizes a series of linear models plus Eutro-WASP and Toxi-WASP. These models simulate the fate and transport of pollutants as they move through the surface water network.

Component 4: Policy/Scenario Definition.

NWPCAM has implemented simplified scenario definitions, such as % change in a pollutant loadings category as well as definitions for very specific policies, such as proposed guidelines for Meat Processing plants and complex scenario definitions such as AFO/CAFO.

Component 5: Water Quality Effects.

The water quality effects are related to the policy definitions and reflect the capabilities of the components 1, 2, and 3 to perform the required analyses. For example, NWPCAM?s capabilities to evaluate complex AFO/CAFO scenarios is a function of the data content of Component 1 and the software tools built into Components 3 and 4.

Component 6: Economic Benefits (Fig. ES-2).

This component is a primary requirement for NWPCAM capabilities. This component has been used in a variety of policy analyses for EPA. These analyses include Clean Water Act retrospective, Stormwater Phase II, AFO/CAFO, and Meat Processing analyses.

Summary of Model Structure and Methods
The water quality modeling system is made up of several interrelated components. The system is built on a surface water routing framework that covers virtually the entire inland region of the continental United States. This framework catalogs where surface waters are located and how they are connected, and it characterizes the dimensions and flow of water through this network. Therefore, three components of NWPCAM?the hydrological, hydrodynamic, and surface water transport components?are integrated into the system through this routing framework.

Pollutant loadings to surface water comprise the fourth major component of the modeling system. This component defines the location and magnitude of discharges to the surface water network. NWPCAM includes loadings for a number of conventional and nutrient pollutants. NWPCAM 2.1 also includes loadings for selected toxic compounds (e.g. mercury). Nutrient and conventional pollutant loadings are defined for both point and nonpoint sources of water pollution. Toxic pollutant loadings are defined for point sources only.

The fifth component of the NWPCAM system is the kinetic models. These models include first-order decay/transformation kinetics. NWPCAM 2.1 has added a more complex kinetics model in the form of the Water Quality Simulation Program (WASP5) model. The kinetics model incorporates information derived from the hydrological, hydrodynamic, surface water transport, and loadings components. It simulates how the selected pollutants are dispersed and transformed throughout the surface water network. The primary output of the modeling system is instream pollutant concentration across the entire network.

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