Proceedings - Teaching and Learning Centre - Simon Fraser ...

Fraser River Action Plan 3rd Research Workshop
Modeling the Impact of Non-Point Source Pollution
in the Salmon River Watershed (Langley) in a Hypertext Framework
H. Schreier, A. Kennedy, B. Wernick, W. Thompson, S. Brown and K. Hall
Institute for Resources and Environment
University of British Columbia
Over the past three years, a comprehensive resource database was compiled for the Salmon River watershed
including water quality and land use information. A Geographical Information System (GIS) served as a
digital base for geo-referenced information such as surficial materials, soil types, land cover and activity,
commercial and hobby farms. Recent changes in the different land use activities were determined from census
data, municipal records, field measurements and historic documents. GIS overlay techniques and statistical
analyses were used to calculate rates of change in land activity, land cover and water quality. Stream and
groundwater quality were related to land uses which were potential sources of contaminants. Both agriculture,
in the form of manure and organic fertilizers, and septic systems contribute significant amounts of nutrients to
the environment. While water quality in the Salmon River is still good in comparison to other urban-rural
fringe streams, there is clear evidence that nitrate concentrations are elevated in approximately one-third of all
groundwater wells. Because groundwater maintains stream flows during the summer, streamwater nitrate
concentrations are also elevated in the Hopington Aquifer area of the watershed.
In order to estimate the future impact of land use on water quality, the watershed was subdivided into 460
unique management units, which were defined by overlaying contributing area units (CA), environmentally
sensitive area units (ESA) and planning units (PU). Four different growth scenarios were projected for each
management unit:
� 2% population increase;
l 5% population increase;
� 50% increase in commercial agriculture with current increase in hobby farms; and,
� current increase in both commercial agriculture and hobby farms.
Total current and future water consumption, surplus nitrogen, % residential areas, green space, population
density and animal unit density were used as indicators of environmental conditions. The results could be
combined into the contributing areas, ESAs or planning units for community planning purposes.
GIS maps, spreadsheet graphs and images showing the results of the data analysis and modeling were
incorporated into a Hypertext system that allows the user to explore the past, current and projected future
conditions in the watershed. Hypertext is an electronic operating system which is a means of extending text
and graphics into multi-dimensional space. Essentially, a Hypertext document is non-linear text which allows
the user to work interactively in a non-structured way with cross-references, annotations, graphics and images
at multi-levels. Pulldown screens containing graphic displays and images are interspersed into the text of the
document.
The Hypertext is a self-contained, self-executable product that can be displayed in color on any personal
computer with VGA graphics capability (10 MB hard drive space and 1 MB of RAM is also required). The
Salmon River Hypertext product is a new way to display and communicate research results which we hope
will reach a wider audience. We consider this an educational tool that will be useful to managers as well as
schools and the public in general. Three examples of the more than 70 screen displays in the document are
shown in Figures 1 - 3).
The fully functioning Hypertext model will be delivered to the Municipality of Langley on April 20, 1996, and
a number of copies will be available at that time.
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