Better Assessment Science Integrating Point and Nonpoint Sources
is a multipurpose environmental analysis system for use by
regional, state, and local agencies in performing watershed- and
water-quality-based studies. It was developed by the U.S.
Environmental Protection Agency's (EPA's) Office of Water to
address three objectives:
- To facilitate examination of environmental information
- To support analysis of environmental systems
- To provide a framework for examining management alternatives
Because many states and local agencies are moving toward a
watershed-based approach, the BASINS system is configured to support
environmental and ecological studies in a watershed context. The system
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 total maximum daily loads (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 nonpoint
sources. BASINS can support this type of watershed-based point and
nonpoint source analysis for a variety of pollutants. It also lets the
user 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
individual 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 nonpoint 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.
A geographic information system (GIS) provides the integrating
framework for BASINS. GIS organizes spatial information so it can be
displayed as maps, tables, or graphics. GIS provides techniques for
analyzing landscape information and displaying relationships. Through
the use of GIS, BASINS has the flexibility to display and integrate a
wide range of information (e.g., land use, point source discharges,
water supply withdrawals) at a scale chosen by the user. For example,
some users will need to examine data at a multistate scale to determine
problem areas, compare watersheds, or investigate gaps in data. Others
will want to work at a much smaller scale, perhaps investigating a
particular river segment impaired by multiple point source discharges.
This "zooming" capability of BASINS makes it a unique and powerful
environmental analysis tool.
Some agencies might wish to perform analyses at a variety of
scales, in a nested fashion, to meet several objectives at once. BASINS
is designed to facilitate all of these scenarios because it
incorporates tools that operate on both large and small watersheds.
Adding locally developed, high-resolution data sources to existing data
layers is an additional option that expands the local-scale evaluation
BASINS comprises a suite of interrelated components for
performing the various aspects of environmental analysis. The
components include (1) nationally derived databases with Data
Extraction tools and Project Builders; (2) assessment tools (TARGET,
ASSESS, and Data Mining) that address large- and small-scale
characterization needs; (3) utilities to facilitate organizing and
evaluating data; (4) tools for Watershed Delineation; (5) utilities for
classifying dems, land use, soils, and water quality observations; (6)
Watershed Characterization Reports that facilitate compilation and
output of information on selected watersheds; (7) an instream water
quality model, QUAL2E;
(8) two watershed loading and transport models, Hydrological Simulation
Program - Fortran (HSPF) and Soil and Water Assessment Tool (SWAT); and
(9) PLOAD, a simplified GIS based model that estimates nonpoint loads
(NPS) of pollution on an annual average basis.
Obtain a copy of BASINS from the
BASINS home page at the
Office of Water