Peer-Reviewed Articles
833 A Feature-Based
Geographic Information System Model
E. Lynn Usery
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A conceptual model for structuring features in a geographic information
system (GIS) is presented. The model includes spatial, thematic, and
temporal dimensions and structures attributes and relationships for
each dimension to build a feature-based GIS. The model is grounded
in an entity-based view of geographic phenomena and requires representation
of geographic entities as feature objects in GIS. The model is built
on concepts from region theoiy in geography, category theory in cognitive
psychology, and data modeling theories, including abstraction and generalization
concepts in cartography and GIS. The feature construct provides direct
access to spatial, thematic, and temporal attributes and relation ships
and thus supports multiple representations and multiple geometries,
such as raster and vector. The rich structure has potential application
for spatial analysis and sophisticated geographic process models. Resolution
and application dependencies of feature-based systems are discussed
with tools to aid in feature determination. Example features are included
with parts of the model explicated for these examples.
839 A GIS-Based Statistical Method to Analyze Spatial Change
Joel D. Schlagel and Carlton M. Newton
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A GIS-based statistical method to examine spatial change was developed
and demonstrated. Each measurement occasion IS mapped as a separate
G1S coverage. Then, using a raster GIS, a nonparametric test for trend
is performed on a per-pixel basis across the collection of coverages.
The spatial component of the data set is maintained, allowing further
spatial analysis of the derived coverage.
The method was applied to a subset of the animal waste management data collected as part of the St. Albans Bay, Vermont, Rural Clean Water Project. It was found that from 1983 to 1990, significant increases (P<0. 10) in the rate of animal waste disposal occurred on 18 percent of the land within 100 metres of Jewett Brook, while significant decreases in application rate occurred on just 3 percent of the riporian land. This suggests that, despite widespread adoption of agricultural best management practices, agricultural activity was, to some extent, working against an improvement in water quality.
845 Using Public Domain Geostatistical and GIS Software for Spatial
Interpolation
C. Varekamp, A.K. Skidmore, and P.A.B. Burrough
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A spatial interpolation system is presented that uses public domain geostatistical
and GIS software from the U.S. and The Netherlands. This paper describes how
component programs were linked together. The system was tested with a case
study involving the mapping of forest soil variables. The system has the advantage
that the program components are of low, or no cost, and are readily available
on the internet.
855 A Regional Information System for Environmental
Data Analysis
B.H.C. Cheng, R.H. Bourdeau, and B.C. Pijanowski
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Many organizations addressing "grand challenge" problems, such as
those defined by Earth sciences, require the integration of both physical and
human resource databases in an interactive manner. Such a capability allows reasonably
informed policy analysts to query an "environmental science workstation" so
as to better understand how human uses impact our natural resource base. This
paper describes a prototype software tool that supports access to and understanding
of diverse environmental information. The tool, ENFORMS (Environmental Information
System), is currently being developed for use in a regional watershed analysis
project. ENFORMS consists of two general components: an object-oriented archive
of multimedia information objects and a querying facility to search the archive
for relevant information. The archive can be populated with a variety of different
types of information, including documents, satellite imagery, aerial photographs,
tabular data, color-coded charts, maps, and illustrative animations. The archive
component also supports data integration activities using tools such as a geographical
information system (GIS) and environmental models.
863 Development of a Geographic Information System for Urban
Watershed Analysis
R.G. Greene and J.F. Cruise
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A geographic information system (GIs) interfaced with a distributed
hydrologic model for urban watershed analysis. Basic data layers are
digitized into a spatial database, and the system topological data
structures are used to generate feature attributes and data products
necessary for modeling. Additional programming allows the system to
use the coordinate values of features in the watershed to directly
calculate flow-plane geometry and routing distances of overland flow
paths, gutters, and storm sewer segments. Access to coordinate values
in the coverages also allows the system to automatically determine
the connecting drainage network, or the order and direction of flow
throughout the urban drainage area. This is a significant improvement
over other systems in which the order and direction of the network
must be determined and digitized by the user. The combined GIS/Modeling
system is capable of analyses of urban drainage problems at a variety
of scales (inlet, block, basin) and at a level of spatial detail not
heretofore accomplished.
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