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giswr
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> 1st nhda symposium
> tuesday >
the gis weasel
The GIS Weasel
An Interface for the Development
of Spatial Parameters for Physical Process Modeling
R. J. Viger, S. M. Markstrom,
and G.H. Leavesley
U.S. Geological Survey
Lakewood, CO
rviger@usgs.gov |
[ slides
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[ no video ] |
The GIS Weasel is a Graphical User Interface (GUI) driven
tool that has been developed as an aid to modelers in the
delineation, characterization, and parameterization of Modeling
Response Units (MRUs) for use in distributed or lumped parameter
physical process models. MRUs are usually defined as land
surfaces that sub-divide an Area Of Interest (AOI), such
as a watershed, to reflect a model's treatment of spatially
distributed characteristics. MRUs can be homogeneous or
heterogeneous with respect to some or all of these characteristics.
The interface does not require user expertise in geographic
information systems (GIS). The user does need knowledge
of how the model will use the output from the GIS Weasel.
The GIS Weasel uses Workstation ArcInfo 8.0.2 and the Arc
Macro Language (AML), as well as scripts, and C subroutines.
The GIS Weasel will run anywhere that Workstation ArcInfo
runs (i.e. numerous flavors of Unix and Windows NT).
The GIS Weasel requires as input an ArcInfo grid of a Digital
Elevation Model (DEM) that describes the topography of the
AOI. The user may select the AOI from a set of watersheds
that can be automatically delineated from the DEM based
on ridges, define their own drainage area based on an interactively
specified watershed outlet point, or use a previously created
GRID or coverage. After the AOI is determined, a drainage
network is extracted from the DEM. The user supplies a value
for the minimum drainage area needed to support a channel.
This value controls the density and configuration of the
drainage network to be derived. Summary statistics and iterative
trials allow the user to experiment before choosing the
final value. Once the AOI and drainage network are established,
MRUs can be delineated according to one or a combination
of several methodologies including logical queries of topographic
(elevation, slope, aspect, etc) or non-topographic (e.g.
vegetation speciation, vegetation density, soils, etc) data,
overlay analyses, and flow-based associations. An MRU can
be composed of single, contiguous polygon or a grouping
of non-contiguous polygons. Menu interfaces for examining
and modifying the MRU map and its attributes are provided.
The GIS Weasel provides version control and documentation
to track modifications of MRU maps. Data derived from the
original elevation grid (e.g.; slope, aspect) or other grids
of attribute data (e.g.; vegetation, soils) can be examined
on the basis of one or more MRUs, by grid cells (point-and-click),
or attribute (logical query and reclassifications). The
statistical distribution of an attribute within single MRUs
or groups of MRUs can be shown. MRUs can be created, grouped,
divided, or eliminated. Once MRUs are defined, user-selected
model parameters can be generated using MRU attributes and
their statistical measures. Output can be created in numerous
formats, including an easy to read and reformat columnar,
space delimited ASCII file.
For more information on the GIS Weasel, see
http://wwwbrr.cr.usgs.gov/weasel.
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