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Model Report

Better Assessment Science Integrating Point and Nonpoint Sources

Last Revision Date: 07/11/2011 View as PDF
General Information Back to Top
Model Abbreviated Name:

Model Extended Name:

Better Assessment Science Integrating Point and Nonpoint Sources
Model Overview/Abstract:
Better Assessment Science Integrating Point and Nonpoint Sources (BASINS) is not a model per se, but is a multipurpose environmental decision support system for use by regional, state, and local agencies in performing watershed- and water-quality-based studies. BASINS was developed by the U.S. Environmental Protection Agency's (EPA's) Office of Water to address three objectives: (1) To facilitate examination of environmental information, (2) To support analysis of environmental systems, and (3) To provide a framework for examining management alternatives. BASINS provides both simple (e.g. PLOAD) and temporally detailed (e.g. HSPF, SWAT, SWMM) models for simulating hydrologic and pollutant loads/concentrations emanating from watersheds. BASINS also provides direct linkages between watershed and detailed aquatic ecosystem simulation models (AQUATOX, WASP), to facilitate analysis of watershed impacts on aquatic ecosystem processes.
Keywords: GIS, Watershed delineation, Watershed models, TMDLs, Hydrology, Fate and Transport, Pollutant loads
Model Technical Contact Information:
Lisa Larimer
U.S. Environmental Protection Agency
Office of Water, Office of Science and Technology
Model Homepage: http://www.epa.gov/ost/basins
Substantive Changes from Prior Version: Unlike previous version, BASINS 4.0 is built upon open-source MapWindow GIS software platform.
Plans for further model development: We hope to continue to incorporate additional environmental models and access to additional kinds of data into the BASINS 4.0 framework in the future.

User Information Back to Top
Technical Requirements
Computer Hardware
200MHz or higher Pentium with a minimum of 300MB of disk space
Compatible Operating Systems
Microsoft Windows 95, 98, 2000, XP
Other Software Required to Run the Model
MapWindow (BASINS 4.0) ArcView with Spatial Analyst (BASINS 3.1)
Download Information
Using the Model
Basic Model Inputs
Misc. GIS data
Basic Model Outputs
Data Download Tool obtains multiple GIS data layers, as well as meteorological, hydrologic and hydraulic (gaging station) and monitoring data. Watershed Delineation Tool employs downloaded GIS data to delineate watersheds with user-specifiable subbasins. Model setup and analysis utilities provide user-friendly interfaces for creating watershed (e.g. HSPF) simulations and evaluating results.
User Support
User's Guide Available?
User Guide is available from the BASINS website
Other User Documents
See http://www.epa.gov/waterscience/BASINS/bsnsdocs.html
Availability of User Support
User support is available from the OST Modeling team. An EPA-mediated listserve also provides support within the user community.
User Qualifications
Knowledge of GIS and hydrologic principles. Background in physical science or engineering is helpful.

Model Science Back to Top
Problem Identification
Because many states and local agencies are moving toward a watershed-based approach, the BASINS is configured to support environmental and ecological studies in a watershed context. It is designed to be flexible. It can support analysis at a variety of scales using tools that range from simple to sophisticated. BASINS was also conceived as a system for supporting the development of TMDLs. Section 303(d) of the Clean Water Act requires states to develop TMDLs for water bodies that are not meeting applicable water quality standards by using technology-based controls. Developing TMDLs requires a watershed-based approach that integrates both point and non-point sources. BASINS supports this type of watershed-based point and non-point source analysis for a variety of pollutants. The user can also test different management options.

Traditional approaches to watershed-based assessments typically involve many separate steps preparing data, summarizing information, developing maps and tables, and applying and interpreting models. Each step is performed using a variety of tools and computer systems. The isolated implementation of steps can result in a lack of integration, limited coordination, and time-intensive execution. BASINS makes watershed and water quality studies easier by bringing key data and analytical components "under one roof." Using the familiar Windows environment, analysts can efficiently access national environmental information, apply assessment and planning tools, and run a variety of proven, robust non-point loading and water quality models. With many of the necessary components together in one system, the analysis time is significantly reduced, a greater variety of questions can be answered, and data and management needs can be more efficiently identified. BASINS takes advantage of recent developments in software, data management technologies, and computer capabilities to provide the user with a fully comprehensive watershed management tool.

Summary of Model Structure and Methods
The model uses mixed U.S. and S.I. units or flexible (user-defined) units. The model provides mathematical guidance to assist the user when selecting modeling parameters.

The model includes a modeling framework that links several related models, modules, or sub-models.

Governing equations are solved numerically and analytically, with solutions available in closed form.

Model Evaluation
There was extensive beta testing (model evaluation) during system development.

Sensitivity analysis has been performed on HSPF in online calibration guidance.

The model has been externally peer reviewed.

QA/QC was performed on each GIS data layer, as described in BASINS meta data.

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