Analysis: A Regional Examination in Alberta, Canada.
Kim Hodge and Neil Gilson
This study examined the utility
of using limited datasets to delineate environmentally sensitive areas
in a rural municipality (M.D.) in Alberta, Canada.The subject M.D. spans
an extremely diverse ecological community along the eastern slopes of the
Canadian Rockies, is located adjacent to a major urban community and is
subject to intense development pressures. Limited, existing, ecological
data were overlaid to delineate environmentally sensitive "hotspots".Hotspots
were compared to existing ecological, biodiversity and wildlife habitat
data and to current patterns of development. Project outputs provide useful
planning information appropriate for identifying areas of concern, scoping
environmental issues, and guiding further analysis and study.
of the project was to develop a planning tool that could be used by the
M.D. of Foothills Environment Committee and Planning Departments to identify
natural resources and ecosystem components of environmental, economic and
social importance, that may be sensitive to the potential impacts of proposed
developments. Specifically, to develop a GIS methodology to evaluate
and map the relative environmental sensitivity of lands throughout the
1.1 Study Area
(Figure 1) has a wide variety of topographic features, generally increasing
in elevation from east to west and, as a result, has significant climatological
and biological diversity. The area transitions from mixed grass ecoregion
(Figure 2) found in the extreme southeast of the municipality, to fescue
grasslands and aspen parkland, which occupy the majority of the M.D., to
the mountainous regions found in the Alberta Upland on the western boundary.
The pattern of human use and development in the M.D. is a reflection of
the natural diversity found across the M.D. landscape. Agriculture
still dominates land use patterns in the M.D. (Figure 3). Cultivated
croplands dominate the eastern portion of the M.D. while lands used predominantly
for grazing and forage occupy the western half. Much of the native
cover of the M.D. has been converted to croplands, forage or tame pasture.
This land use pattern is rapidly changing. The proximity to Calgary
has brought increased pressures for country residential development and
recreation opportunities to the northern half of the M.D..
Figure 1: M.D. of
Figure 2: Ecoregions
in the MD of Foothills
Figure 3: Landcover
in the MD of Foothills
communities within the Ecoregions include three primary types of grassland
communities, ranging from the rough fescue-sedge communities of the Western
Alberta Uplands to parry oatgrass-rough fescue communities of the Foothills
Fescue grassland Ecoregion. Plant species more commonly associated
with the needle and thread-blue gramma grass - wheat grass communities
of the Mixedgrass Prairie Ecoregion can also be found well into the central
part of the M.D. on suitable sites. Forest cover in the M.D. is also
diverse with lodgepole pine-white spruce dominating undisturbed sites in
the western portion of the M.D. and giving way to limited aspen-balsam
poplar communities in the central and eastern portions of the M.D..
Willow and birch shrublands also make up a considerable portion of the
native plant cover in the western and central portions of the M.D..
been considerable work at the provincial scale to identify environmentally-significant
in the province. These areas are based on their representativeness,
diversity, naturalness and ecological integrity. This work has resulted
in the identification of areas at a provincial, national, and international
scale within the province. Designation at this scale is of limited
use for management and protection of natural resources and ecosystem processes
at the scale of the M.D.. This project refines the environmentally
significant areas evaluation process to identify environmentally-sensitive
areas at a scale useful for planning for the M.D..
purposes of this study, environmentally sensitive areas (ESA's) include
key physical ecosystem components and complexes that are vulnerable to
the potential impacts of a broad range of land use, development and management
activities, particularly, the alteration, disruption or destruction of
fish and wildlife habitat, permanent or temporary soil disturbance, the
removal or modification of native vegetation cover, or the release of biological
or chemical contaminants. Environmentally-sensitive areas also include
ecosystem or landscape elements where the impacts of land use, development
or management activities as described above may directly or indirectly
affect ecosystem areas or features.
a number of individual studies to identify candidate environmentally-significant
areas the biophysical and climatic variation found within the M.D. remains
under-represented by proposed environmentally-significant models.
Past work related to the designation of protected spaces or environmentally-significant
areas in the M.D. has resulted in a series of proposed areas primarily
concentrated along the western boundary of the M.D. These areas have
also been identified for portions of the Sheep, Highwood and Bow Rivers
and for a portion of Pekisko Creek. Other small areas in the central
and eastern portions of the M.D. have been identified as environmentally-significant
areas including Frank Lake and the Okotoks Erratic. Generally however,
the grasslands and boreal forest ecoregions, and their associated wildlife
and plant populations are poorly represented in past environmentally-significant
areas studies. In addition, past studies have not considered environmentally-significant
areas in the context of a larger connected reserve network, in terms of
habitat fragmentation or patch size.
identifies environmentally sensitive area within the M.D. of Foothills
based on the evaluation of limited spatial data, such as groundwater, surface
water and terrestrial ecosystem components. Natural resource and
cultural data were collected to provide the baseline information for evaluation.
Sensitive environmental features and sensitive zones surrounding those
features were identified based on professional judgment and reviews of
related literature and existing information. The relative sensitivity
of any given land location within the M.D. was evaluated by ranking each
feature and sensitive zone using a simple numerical index (Table 1).
Sensitive features were then overlaid with each other using a GIS.
The relative sensitivity of a given area was established by simply calculating
the sum of total index values of the overlapping sensitive features occupying
any given area.
Table 1: Environmental
Sensitivity Ranking Criteria
0-300m from nearest road
Parks and Protected Areas
Inside Administrative boundaries
Riparian Sensitive Zones
Provincial Code of Practice Class D
Provincial Code of Practice Class C
Provincial Code of Practice Class B
Provincial Code of Practice Class A
Numerically higher values
indicated more potential sensitivity
Groundwater Sensitivity Analysis
sensitivity analysis for this project does not deal with the issues of
groundwater sourcing, groundwater allocation, or aquifer depletion.
While these are important and legitimate issues with respect to development
plans and approvals, for the purpose of an environmentally-sensitive lands
evaluation they are excluded because this type of information does not
exist for the M.D. Identification of aquifers at risk of depletion
is a time and money-intensive task requiring considerable fieldwork beyond
the scope of this project. Groundwater withdrawal is controlled and
licensed by the Government of Alberta and as such, decisions with regard
to allocation are beyond the direct control of the M.D. For the purpose
of identifying environmentally sensitive areas, this evaluation considers
groundwater sensitivity from the perspective of potential vulnerability
to contamination as a result of land development or land use activities
study, the approximate regional vulnerability to contamination (Figure
4) has been estimated using surficial geology data. Materials of
coarser texture such as river-lain sands or gravels are more permeable
and allow more rapid infiltration of contaminants to shallow groundwater.
These areas have a relatively higher contamination risk. Conversely,
thick lacustrine clays are relatively impermeable and pose a very low contamination
risk to shallow groundwater. Fractured glacial tills pose a moderate
to low risk.
Figure 4: Groundwater
were ranked into one of four risk categories (Low, Medium, High or Very
High) based on the assumed vertical permeability of the geological material.
Each groundwater sensitivity category was also assigned an environmental
sensitivity value ranging from 1(Low) to 4(Very High). This value
was used to contribute to the calculation of overall environmental sensitivity
in combination with other factors (see Section 3.3). Areas at Very
High or High vulnerability to shallow groundwater contamination may be
considered to be of considerable environmental sensitivity due to potential
effects on groundwater and surface water resources.
vulnerability information is used most appropriately to gauge the relative
vulnerability of an area. This evaluation should not be considered
a definitive or quantitative evaluation of the actual risk of groundwater
contamination for any given area. However, an area may be judged
to be more sensitive to contamination than another area under the same
development conditions. Actual risk for individual projects can only
be determined by a site-specific investigation under the direction of a
evaluation identifies groundwater contamination as an issue that should
be specifically addressed within development proposals through alternative
site selection and /or mitigation strategies and identifies the need for
additional groundwater studies. The groundwater vulnerability evaluation
also contributes to an understanding of regional environmental sensitivity
when evaluated in concert with other intrinsically connected factors such
as surface water resources and fish and aquatic wildlife habitat.
Surface Water Sensitivity Analysis
riparian zone, the area where vegetation type and abundance is influenced
by the elevated water table and deep soils adjacent to a water body, is
often identified as an environmentally sensitive zone. Healthy riparian
zones provide a number of critical ecological services, and their importance
to both aquatic and terrestrial ecosystem function is critical despite
the relatively small geographic area they occupy within a watershed.
A variety of literature
was reviewed to identify methods or procedures for mapping environmentally
sensitive lands surrounding surface water features (lakes, ponds, wetlands,
and streams). The review was concentrated primarily on Provincial
and Federal Government Guidelines, Codes of Practice, and Standards related
to petroleum, forestry, and livestock operations as well as subdivision
developments. A limited review of related scientific literature was
also conducted. Ecological and distance criteria for the designation
of riparian buffer zones were identified as the primary result of the review.
for application within the M.D. of Foothills were derived from the literature,
from observations made in the field, from consultation with Provincial
Fish and Wildlife Biologists, and through consultation with water and land
management specialists from PFRA. Recommendations from the literature
can be classified into two primary categories - those approaches that rely
on a specified fixed-width setback distance, and those that rely on the
evaluation of site-specific ecological criteria. Minor watercourses
(intermittent streams, wetlands) should be protected with a 30 and 100
m buffer. Larger, permanent streams and lakes should be protected
with a 30, 100 and 200 m buffer (Table 1). Each buffer zone needs
a different type and level of protection and management.
3.3 Terrestrial Environment
Biodiversity Species Observation Database (BSOD)
is managed by Alberta Sustainable Resource Development and provides observation
data on all sensitive wildlife species or wildlife species at risk (Figure
5). The BSOD consists of point data with location accuracy ranging
from 200m to 5000m. The time frame of the observation data ranges
from long term, multiple observations of a species occupying a site over
time to single one-time observations. Some of the data was collected
some time ago and may suggest wildlife use of an area that no longer occurs.
Conversely, the lack of observation data does not suggest that a given
species does not occupy a particular location.
Despite these limitations,
the BSOD is useful in that it identifies potential wildlife issues within
the accuracy limits and suggests potential wildlife use of similar sites
in the general area of the observation. Multiple observations in
the same location over time are likely a reasonable indication that the
area serves as important habitat for sensitive species. Observation
data was buffered using the accuracy field in the database to identify
the radius within which the observation occurred.
3.3.2 Alberta Natural
History Information Centre (ANHIC) Rare Plants Database
Rare Plants Database (Figure 5) is similar in nature to the BSOD in that
it consists of point data with limited accuracy. As with the BSOD,
the Rare Plant Database is useful in that it identifies the general locations
of rare species and highlights the potential need for site-specific vegetation
studies or consultation with ANHIC or Alberta Sustainable Resource Development.
Significant Area studies pertaining to the M.D. of Foothill have been conducted
several times in the past and include studies by the Calgary Regional Planning
Commission and Alberta Environment. The Environmentally Significant
Areas designated through past studies were reviewed and mapped in an independent
report conducted for the Environment Committee in 1998 (Figure 5).
the M.D. has found that the past studies do not suit its purposes, it is
worth noting that the Environmental Reference Manual for the Review of
Subdivisions in Alberta (Alberta Environment 1996) specifically refers
to impacts on Environmentally Significant Areas as designated by the Province.
In particular, Chapter 4(I) states "major environmental constraints to
development, as well as potential adverse impacts on Environmentally Significant
Areas, may be mitigated in some cases by lot redesign and site-specific
environmental evaluations". This reference suggests that development
within an Environmentally Significant Areas is intended to be quite restrictive
and is intended to be an exception rather than the rule. Provincially
designated Environmentally Significant Areas should be considered in accordance
with the Manual and related Acts regardless of other M.D. objectives or
alternative designations of environmentally significant areas.
Figure 5: BSOD, Rare
Plants, and Environmentally Significant Areas
on vegetation cover and land use in the M.D. is taken from Classified Landcover
database interpreted from 1995 satellite imagery (Figure 3). The
data has a 30m resolution and separates land cover into broad categories
including grassland, shrubs, trees, forage and cultivated lands.
No distinction is made between native grasslands or tame pastures or for
different forest cover types. In addition to the above limitations,
land uses are constantly changing; trees are cleared for pasture or development,
aspen forests encroach on grasslands over time, native grasslands are replaced
with tame grasses, crop types and forages are alternated or changed.
All of these limit the accuracy of the data, particularly with regard to
however, the Classified Landcover provides an accurate depiction of vegetation
cover and land use patterns across the M.D.. As such, it is useful
for identifying broad areas that may be suitable as wildlife habitat.
Areas of forest, shrub and grassland cover are generally considered to
be less disturbed than areas of forage or cultivation and to support greater
levels of native biodiversity. These areas can be considered to be
the most sensitive in terms of potential impacts to wildlife and habitat.
Native grasslands are among the most endangered ecosystems on the prairies
and most wildlife species in the M.D. that are listed as "at risk" or "sensitive"
by Alberta Sustainable Resource Development are strongly associated with
native grasslands. A detailed survey of native grasslands in the
M.D. would be a very valuable tool for evaluating environmental sensitivity.
This is not to suggest that lands in forage or in cultivation have no values
for wildlife. Ungulates and waterfowl in particular use these areas
for feeding and nesting habitat. However areas in forage or cultivation
can be seen to be relatively less sensitive than lands that remain under
native cover. Few sensitive species or species at risk rely on cultivated
or forage lands as habitat.
3.3.5 Parks and Protected
and Protected Areas managed by Alberta Sustainable Resource Development,
Alberta Community Development, Heritage Canada or non-government organizations
were mapped as sensitive areas. There are very few protected areas
in the M.D. the largest being the 1942ha Ann and Sandy Cross Conservation
Area. These areas may serve as important core wildlife habitat or
protect valued cultural or heritage features e.g., Bar U Ranch Historic
use and land development activities immediately adjacent to protected areas
may have deleterious impacts that extend well into parks and protected
areas making them effectively smaller as wildlife habitat. Impacts
may include noise and visual disturbance, vandalism and accidental damage
by humans e.g., fire, predation from domestic animals, colonization of
invasive species, chemical contamination from herbicides or pesticides,
and removal of vegetation that may reduce protective cover and increase
the intensity of edge effects. Variable width buffers utilizing zoning
designations similar to those for riparian sensitive zones should be established
on a case-by-case basis for all parks and protected areas in the M.D..
Parks and protected areas were buffered at a distance of 500m for the purposes
of this study.
3.3.6 Roadless Lands
areas and other undeveloped landscapes can be expected to contain wildlife
species sensitive to human activities and disturbance. Large species
such as black bear and predators such as cougars are particularly sensitive
to human disturbance and require large areas to accommodate their home
ranges. Most species at risk are also sensitive to human caused disturbance
or modification of natural habitats.
Considered in isolation,
roadless or undeveloped lands do not necessarily indicate environmentally
sensitive lands. However when considered in combination with other
factors such as vegetation cover and the presence of species at risk, roadless
lands may indicate prime areas for the designation of protected areas or
the implementation of environmental protection and conservation management
measures. For this project roadless lands were calculated and mapped
based on 1:20,000 transportation data (Figure 6)
Figure 6: Roadless
of Foothills specifies slope limits for the development of roads and building
sites. Roads are not to exceed a grade of greater than 7%.
Building parcels are not approved on slopes exceeding a grade of greater
than 15%. While these specifications are primarily intended for pragmatic
operational, maintenance and safety purposes, steeper slopes may also be
considered to have greater potential for erosion, and the transfer of sediment
and contaminants downstream during runoff events is accomplished more quickly.
Disruption of vegetation on steep slopes may exacerbate these potential
issues. Steeper slopes are the least likely to have been broken for
agriculture or heavily grazed and may be among the least disturbed native
vegetation environments in the M.D.. Slope maps can be used to help identify
areas at risk of erosion or that may affect water quality by expediting
the movement of contaminants downhill or downstream.
maps were created for the M.D. using Digital Elevation Model (DEM) data.
Although maps with any slope interval can be created with the DEM, for
the purposes of this project it was decided to use the specifications that
the M.D. planning staff already use for evaluation of development plans;
0-7%, >7-15%, >15% (Figure 7).
Figure 7: Slope Classification
Environmentally Sensitive Lands Analysis
of the environmentally sensitive lands analysis is to provide the Environment
Committee with a way to evaluate and compare the relative environmental
sensitivity of lands across the M.D.. The analysis accomplishes this
task by mapping and ranking concentrations of sensitive ecological variables
from the groundwater, surface water and terrestrial evaluations.
variables included the analysis are:
RSZs ranked by fish habitat
Parks and Protected Areas
data were converted to raster format. Each variable was assigned
an environmental sensitivity value from 1 (least sensitive) to 4 (most
sensitive). Numerical scores were based on existing available rankings
for aquifer vulnerability. The remaining variables were assigned
scores on the basis of professional judgments about the relative sensitivity
of each feature to potential development impacts. Environmental sensitivity
values for each variable are summarized in Table 1.
The sensitivity values for
each variable occupying any given cell were summed to yield a total score
for each cell (ArcGIS 8.1 GRID). The possible score for any given
cell ranges from 0 (sites with no data) to 24 (sites where the value for
every variable = 4). The data were classified into 4 classes using
the Natural Breaks default classification method in ArcView 3.2.
This method identifies breakpoints between classes using a statistical
formula (Jenk's optimization). The Natural Breaks method finds groupings
and patterns inherent in the data. The resultant map provides a graphic
representation of the location, pattern and concentration of sensitive
ecological variables across the M.D. (Figure 8).
Figure 8: Environmentally
Sensitive Areas Analysis