ENVIRONMENTAL MONITORING AT A PROVINCIAL SCALE 
Providing GIS Compatible Thematic Data 
Through the Integration and Analysis of 
Digital Elevation Models and Satellite Imagery 
Malcolm Gray and Fern Schultz 
British Columbia Ministry of Crown Lands 
Surveys and Resource Mapping Branch 
553 Superior Street 
Victoria, British Columbia, CANADA, V8V 1X5 
Telephone: (604)387-1146 FAX: (604)387-3022 
ABSTRACT 
In order to be an effective tool for provincial resource management and environmental monitoring, 
Geographic Information Systems (GIS’s) require access to information that is not only comprehensive, 
standardized, digital, and current, but is also available Province-wide. Much of the existing provincial 
resource mapping fails to meet one or more of these criteria. 
In an attempt to overcome this lack of suitable data, a method is being prototyped that uses digital 
topography and satellite imagery to provide a geo-referenced resource database of ground cover, present land 
use and topographic features. This product is called a Baseline Thematic Map. 
Technical obstacles which are being addressed include; registration issues (including relief displacement), 
classification schema definition, raster and vector format conversions, integrity of the input data and 
topographic segmentation of digital elevation models. 
The application of this mapping methodology for a large area (170 000 sq. km., 1:250 000 map scale) is 
discussed. Application at a scale of 1:20 000 is also discussed. Results have shown that an economically 
valuable database can be produced that is reliable, up-to-date and suitable for supporting regional 
environmental decision making. 
KEY WORDS: Satellite Imagery, Digital Topography, GIS, Resource Management, Thematic Mapping 
1 INTRODUCTION 
The management of British Columbia’s natural 
resources is becoming an increasingly complex task. 
Reasons for this trend include: a shift from resource 
inventories to site specific management, integrated and 
coordinated management of multiple resources, and a 
requirement to more strictly monitor and regulate 
environmentally harmful substances and activities. 
Many of the issues must be addressed at a provincial 
level. 
The economic potential of Geographic Information 
System (GIS) technology to support planning and 
decision making has been realized by the Government 
of British Columbia. GIS technology provides resource 
managers with a powerful tool which has the potential 
to efficiently meet the requirement for information 
analysis. For such a tool to be effective in a manager’s 
ongoing activities, it requires access to resource 
information that is not only reliable, comprehensive, 
standardized, digital, and up-to-date, but is also 
available Province-wide. In this regard an examination 
of the resource mapping carried out to date in the 
Province leads to the conclusion that much of it is not 
suitable for use in a GIS. In addition it has become 
increasingly difficult to justify new natural resource 
mapping using traditional methods for two reasons: 
time and cost (Gray et al., 1989). 
In an attempt to overcome these limitations an 
efficient, cost effective method using presently available 
data sources to provide suitable geo-referenced natural 
resource map data is being prototyped. The final 
objective is a product capable of justifying a 
production level implementation. 
The method involves the production of three natural 
resource data bases, specifically; ground cover, present 
land use and topographic features. After integration 
into a single database the resultant product is called 
a Baseline Thematic Map. The databases are derived 
from an integration of digital topography and satellite 
imagery by a series of procedures involving image 
analysis, topographic modelling and GIS processing. 
2 SPECIFIC RESPONSE TO THE REQUIREMENT 
FOR PROVINCE-WIDE NATURAL RESOURCE 
DATABASES 
Past pilot projects undertaken by the Surveys and 
Resource Mapping Branch have shown that 
classification of satellite imagery can meet traditional 
map accuracy specifications (Kenk et al., 1988). Results 
reported in the literature indicate that by including 
topographic information the number of classes mapped 
can be increased while maintaining map accuracy 
(Cibula et al., 1987). 
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