INTRINSIC AQUIFER VULNERABILITY MAPS IN SUPPORT OF

SUSTAINABLE COMMUNITY PLANNING, OKANAGAN VALLEY, BC

Jessica Liggett, Simon Fraser University, Burnaby, BC, Canada Diana Allen, Simon Fraser University, Burnaby, BC, Canada Murray Journeay, Geological Survey of Canada, Vancouver, BC, Canada Shannon Denny, Geological Survey of Canada, Vancouver, BC, Canada Sonia Talwar, Geological Survey of Canada, Vancouver, BC, Canada Lex Ivey, TerraCognito GIS Services, Eldorado, CO, USA ABSTRACT The Okanagan Valley, in south central British Columbia, is an increasingly popular area for agriculture, tourism, and residential development. Community growth can be detrimental to groundwater resources as water use increases. Spatially distributed intrinsic aquifer vulnerability of the south Okanagan Basin was mapped utilizing the GIS-based, DRASTIC model. DRASTIC takes into account the Depth to water table, net Recharge, Aquifer media, Soil media, Topography, Impact of the vadose zone, and hydraulic Conductivity of the aquifer. Ranges within each characteristic are rated based on their relative vulnerability, each characteristic is multiplied by a set weight, and all seven are added together to produce a final relative aquifer vulnerability rating. The vulnerability map has been integrated with other criteria into a Land Use Allocation Model for use as part of the Smart Growth on the Ground program in Greater Oliver. This interdisciplinary team helps to achieve more sustainable communities by creating tangible, built examples of smart growth. RÉSUMÉ Situé dans le centre-sud de Colombie-Britannique, la vallée de l'Okanagan est un region de plus en plus populaire pour l'agriculture, le tourisme, et le développement résidentiel. La croissance de la communauté peut être nuisible aux ressources d'eaux souterraines, il est essentiel que la qualité de ces ressources soient suffisantes pour supporter tous les activités dans cette region. La vulnérabilité du système aquifère régional à la contamination a été évaluée dans le bassin de l'Okanagan à partir d’un méthode axé sur le SIG, DRASTIC. Les sept lettres de l’acronyme DRASTIC représentent les facteurs qui évaluent la valeur de l’indice de vulnérabilité: (1) la profondeur de la nappe d’eau, (2) infiltration efficace, (3) milieu aquifère, (4) type de sol, (5) pente du terrain, (6) l'impact de la zone vadose, et (7) conductivité hydraulique. Les gammes dans chacun facteur sont évaluées basées sur leur vulnérabilité relative, chacun facteur est multiplié par un poids determiné par la methode DRASTIC, et chacun des sept facteurs sont additionné ensemble pour produire une estimation relative de vulnérabilité du système aquifère. Les cartes de vulnérabilité sont intégrées dans un modèle d'attribution d'utilisation des terrains en collaborations avec le programme ”Smart Growth on the Ground” dans la grande region d’Oliver. Cette équipe interdisciplinaire identifie de futurs scénarios pour etablir la croissance durable de la communauté. 1. INTRODUCTION Okanagan Valley, located in south central British Columbia (BC) (Figure 1), is a growing locality for residential development, tourism and agriculture. Community growth can be detrimental to groundwater resources as municipal and agricultural water use, and industrial development rises. Community awareness of potential contamination of groundwater resources is important for promoting sustainable development. Likewise, sustainable community development is an important topic of discussion for communities, governments, and researchers. As part of a Canadian Water Network (CWN) funded project, the intrinsic aquifer vulnerability of the Okanagan Basin will be mapped utilizing the GIS-based, DRASTIC, aquifer vulnerability model. There will be a focus on the

Kelowna, Vernon, and Oliver areas; however, this paper focuses on preliminary vulnerability maps created for Electoral Area C, in Greater Oliver in the south Okanagan (Figure 1). These vulnerability maps will provide communities with a guide to base land use planning, site assessments, identification of potential protected sites (Aller et al. 1987), and other sustainable development concerns. One component of the CWN project involves partnering with Natural Resources Canada's Pathways project. Greater Oliver was selected as a case study area for PATHWAYS to contribute to the Smart Growth on the Ground (SGOG) initiative by identifying future growth patterns through the development of a Land Use Allocation Model (LUAM). SGOG is represented by an interdisciplinary team working towards a sustainable development plan in the Oliver area. The LUAM will

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Figure 1. Okanagan Valley, British Columbia. Outlined area is Greater Oliver, Electoral Area C, where preliminary vulnerability maps have been constructed. incorporate the Greater Oliver vulnerability maps as a constraint into a GIS-based land use model. 2. OKANAGAN VALLEY The Okanagan Valley Basin is located in south central BC, about 250 km east of Vancouver (Figure 1). The basin extends from north of Armstrong nearly 200 km south into Washington State. The basin is semi-arid: Osoyoos, in the south Okanagan, receives ~320 mm/yr of precipitation, while Armstrong, in the north, receives ~490 mm/yr. Mean annual air temperature varies from 10.2°C in Osoyoos to 7.1°C in Armstrong (Environment Canada 2006). Okanagan Basin is characterised by a long north-south trending valley, with Okanagan Lake extending almost half the basin length (Figure 1). The valley is filled with Quaternary and Holocene gravels, sands and silts. The elevation in the basin ranges from approximately 270 metres above sea level (masl) to 2580 masl. 3. AQUIFER VULNERABILITY Intrinsic aquifer vulnerability is a measure of the susceptibility of an area to groundwater contamination

due to characteristics of the aquifer and overlying material. Vulnerability maps are useful for planners, developers, and governments to utilize when questions of potential groundwater contamination arise. These maps can be used as a screening tool for development planning, identifying potential highly sensitive areas, and for prioritizing and designing monitoring programs (Aller et al. 1987). Vulnerability mapping does not replace site-specific investigations, nor identify suitable areas for industry or landfills. These mapping projects are to be used as a guide to direct planners, to asses the level of site investigation needed, and to emphasize highly vulnerable areas. Aquifer vulnerability has been completed in other areas of BC, most notably in the Gulf Islands (Denny et al. in review), Grand Forks (Wei et al. 2003), and the Fraser Valley (Wei 1998). In each area, the DRASTIC method of aquifer vulnerability was used. The Fraser Valley was also mapped with the Aquifer Vulnerability Index (AVI) method. Aquifer vulnerability has also been assessed by the BC Ministry of Environment (MoE) using the BC Aquifer Classification System; however, the extent of the aquifer polygons is limited to populated areas with water well data. 3.1 DRASTIC The DRASTIC aquifer vulnerability model was developed in 1987 for the US Environmental Protection Agency (Aller et al. 1987). DRASTIC is a regional model for areas bigger then ~40 ha (100 acres), such as the Okanagan. The model considers a contaminant introduced at the surface, and which moves downwards due to recharge from precipitation at a rate equal to water movement (Aller et al. 1987). The vulnerability of the aquifer is assessed by examining intrinsic properties of the aquifer and vadose zone, the water table depth, topography, and recharge. To evaluate of the relative intrinsic aquifer vulnerability of an area, DRASTIC incorporates the spatial distribution of seven characteristics: the Depth to water table, net Recharge, Aquifer media, Soil media, Topography, Impact of the vadose zone, and the hydraulic Conductivity of the aquifer (Figure 2). An additional characteristic, Fracturing of Media, has been developed by Denny et al. (in review) for use in areas with fractured bedrock aquifers. Each of the seven DRASTIC characteristics are grouped into ranges and assigned a rating from one (the lowest vulnerability) to ten (the highest vulnerability). Examples of typical ranges and ratings of all seven characteristics are provided by Aller et al. (1987). These ranges and ratings may be manipulated by the user to suit the area of study (Aller et al. 1987). Table 1 identifies the ranges and ratings assigned to each DRASTIC characteristic for mapping vulnerability in the Okanagan.

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Table 1. Ranges and ratings used in DRASTIC aquifer vulnerability mapping of the Greater Oliver area (Electoral Area C). VP, very poor; P, poor, I, imperfect; M, moderate; W, well; R, rapid.

Ranges

Rating Depth to

Water (m)

Recharge

(mm/yr)

Aquifer

Media

Soil media

(Drainage)

Topography

(Slope %)

Impact of the

Vadose Zone

-log K (m/d)

Hydraulic

Conductivity -

log K (m/d)

1 > 30.5 0 - 51 VP > 30 < -4.5 < -0.5

2 22.9 - 30.5 51 - 102 Argillite and chert VP, P, I, M 15 - 30 -4.5 to -3.5 -0.5 to 0.5

3 15.2 - 22.9 Igenous and metamorphic P, I, M 9 - 15 -3.5 to -2.5

4 I, M -2.5 to -1.5 0.5 to 1.5

5 9.5 - 15.2 M, W 5 - 9 -1.5 to -0.5

6 102 - 178 Siltstone W -0.5 to 0.5

7 4.6 - 9.5 W 0.5 to 1.5

8 178 - 254 Sand and gravel W, R 1.5 to 2.5

9 1.5 - 4.6 > 254 R 2 - 5 < 2.5

10 0 - 1.5 R 0 - 2 no vadose zone > 1.5

Figure 2: Schematic diagram of DRASTIC vulnerability mapping method (courtesy of B. Turner and R. Franklin) The final vulnerability (V) of an area is calculated by the sum of the multiplication of each characteristic’s rating (r) by its set weight:

rrrrrrrCITSARDV 3512345 ++++++= [1]

The weights of each characteristic are constant and cannot be changed (Aller et al. 1987). The vulnerability of a particular area may range from 23 to 230. A higher vulnerability rating indicates an increased pollution potential. Table 2 identifies the data sources used for mapping vulnerability in Electoral Area C. All seven characteristics were mapped in the geographic information system (GIS) ArcGIS 9.1 (ESRI 2005) and converted into raster format. The seven raster maps were multiplied by their weights and added together to produce the final, spatially distributed, map of intrinsic aquifer vulnerability. 3.2 DRASTIC Characteristics 3.2.1 Depth to Water The BC MoE database contains 710 water well records for the Oliver area; 603 well records contain water level data. Most water wells are located in the valley bottom where a majority of agriculture and population is located. Wells are predominantly drilled into unconfined Quaternary sand units of fluvial, glaciofluvial, and alluvial origin (Wei 1985). Some well logs show sand units confined by silts or clays, but the lateral continuity of the confining layers is uncertain. Of the 546 wells drilled into surficial sediments, 96% have a depth to water less than 20 m; and 82% have a depth to water less than 9.5 m deep, corresponding to a vulnerability rating of seven or greater. Few (58) of the wells in Electoral Area C are drilled into bedrock, and most of these are located along the valley bottom edges and uplands. Only 48% of bedrock wells have a depth to water less than 9.5 m (rating of seven or greater).

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Table 2. Data sources and data types used in the aquifer vulnerability mapping of the Greater Oliver area (Electoral Area C).

Data Source Data

BC Ministry of Environment (BC MoE) 1:20 000 soil survey of valley bottom; water well database; aquifer classification; pump test data; chemical well analyses (nitrate data)

BC Ministry of Energy, Mines, and Petroleum Resources Bedrock geology Forest Renewal BC (FRBC) 1:50 000 soil survey of upland areas

Geological Survey of Canada (GSC) Digitized surficial geology Geobase.ca 1:50 000 digital elevation models (DEMs)

Environment Canada Climate data Field Collection Nitrate data; soil permeability

Determining the spatial distribution of the depth to water in the valley sides is difficult due to the lack of data in these areas. Ordinary contouring of the depth to water data points did not produce favourable results in the valley sides and uplands. In the Gulf Islands, depth to water was determined by establishing the relationship between depth to water and ground elevation (Denny et al. in review). This method was explored, but no consistent relationship was found. It is likely that the water table is controlled by smaller-scale topography rather than the general valley structure. The depth to water table surface was determined by cokriging, utilizing the water table elevation and ground elevation as covariants. Depth to water (Figure 3) was determined by subtracting the water table and ground elevations. The water table elevation in the uplands is greatly affected by the type of variogram. Several different variograms were modelled before selecting an appropriate model. This variation is likely due to the lack of water well data points in the uplands. Control points were added to the valley bottom along water bodies such as lakes and rivers, but did not produce favourable results when added to upland water bodies. 3.2.2 Net Recharge For the preliminary map (Figure 3), a constant recharge value of 40 mm/yr was used (Toews, personal communication). The vulnerability rating associated with this recharge rate is the lowest possible (Table 1). It does not seem necessary to exactly quantify spatial distribution of recharge because a range of values is given a single vulnerability rating. The Okanagan is semi-arid and it is unlikely that the amount of recharge would extend beyond a rating of one or two. The vulnerability rating may be increased in irrigated areas where recharge is elevated. The effects of irrigation have not yet been incorporated into the vulnerability maps for Electoral Area C. 3.2.3 Aquifer Media Two main aquifer types are identified in the Okanagan Valley: unconfined or partially confined sand and gravel aquifers in the surficial sediments of the valley bottom, and igneous and metamorphic bedrock aquifers in the

valley sides and uplands. The sand and gravel aquifers are assigned a rating of eight, while the igneous and metamorphic aquifers assigned a rating of three (Figure 3). Two upland areas in the northwest of Electoral Area C (Figure 3) contain sedimentary bedrock. The siltstone bedrock aquifer is rated six, while the argillite and chert bedrock aquifer is rated two. The aquifer vulnerability ratings correspond to those suggested by Aller et al. (1987), and used in the Gulf Islands (Denny et al. in review) and Grand Forks (Wei et al. 2003). 3.2.4 Soil Media Two different datasets are used to map the soil media: a comprehensive 1:20 000 BC MoE survey of the valley bottom, and a FRBC 1:50 000 survey in the valley uplands. The BC MoE dataset contains data on individual soil horizons, whereas the valley uplands soils data are much more generalized. The edges of the two datasets are not congruent; gaps and overlaps exist along the sides of the valley. The BC MoE soil polygons were used where polygons overlapped; however, gaps were left as is, rather than arbitrarily modifying polygons. The ranges and ratings for soil media were modified from those suggested by Aller et al. (1987). Soil ratings were primarily based on soil drainage rather than soil texture. Well drained soils were assigned a higher vulnerability rating than poorly drained soils. Soil texture was used to divide soils further, where finer grained soils were rated lower than coarse grained soils. Figure 3 illustrates the vulnerability rating for the soil media characteristic. 3.2.5 Topography Topography is rated by the slope, according to ranges suggested by Aller et al. (1987) (Table 1). Two different methods were used to map and rate the slope (Figure 3). The first utilizes the dominant slope recorded for each soil polygon. This provides a simplified topography rating. The second method is more spatially variable and utilizes the slope derived from the DEM. The DEM derived slope is used to calculate the overall aquifer vulnerability; although, differences between the two methods do not significantly affect the overall vulnerability because topography is weighted the lowest of all seven characteristics.

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Figure 3: Seven DRASTIC input characteristics for the Greater Oliver (Electoral Area C) aquifer vulnerability maps. 3.2.6 Impact of Vadose Zone The ranges and ratings for the impact of the vadose zone are consistent with those used in the Gulf Islands (Denny et al. in review), Grand Forks (Wei et al. 2003), and the Fraser Valley (Wei 1988). Aller et al. (1987) suggested ratings based on material type, whereas the BC studies have utilized ratings based on saturated hydraulic conductivity of overlying material (Table 1). This allows vulnerability ratings to be determined for areas with multiple overlying deposits. The conductivity of the material above the water table was determined with a weighted geometric mean of the conductivity of each layer and its thickness. The vadose zone rating in the valley bottom is based on a conceptual model containing a soil layer above a parent material, overlying the aquifer material. Data are available for the thickness and texture of each soil horizon, and for the type of soil parent material. It is assumed that the water table coincides with the top of the aquifer.

Saturated hydraulic conductivity values for each soil texture and parent material were used from Schroeder et al. (1994) and Freeze and Cherry (1979), respectively. The thickness of the parent material is calculated by subtracting the soil thickness raster map form the depth to water table map in the GIS. The vadose zone rating in the valley sides and uplands is based on a conceptual model of soil above parent material, above the bedrock aquifer. The upland soil survey data does not include soil thickness; therefore, a soil thickness of 1 m was used based on average thickness in the valley bottom. Just over 75% of the 58 bedrock water wells have less than 20 m of material above the bedrock. The average thickness of the overburden material in these 75% is about 10 m. Therefore, it is assumed that the thickness of the parent material is 10 m. The hydraulic conductivity of each soil type was determined from an average of the conductivity of each soil texture listed. The hydraulic conductivity of the bedrock was determined from Freeze and Cherry (1979) as no hydraulic test data within bedrock wells were available. 3.2.7 Hydraulic Conductivity The rating scheme for hydraulic conductivity (Table 1) is similar to that used in the other BC studies, and suggested by Aller et al. (1987). Ranges of hydraulic conductivity values listed in Freeze and Cherry (1979) for sand and gravel correspond to a vulnerability rating of 10. A hydraulic conductivity of 6.7 x 102 m/d was determined by slug testing for an observation well completed in a sand and gravel aquifer (Liskop 2004). This hydraulic conductivity also corresponds to a vulnerability rating of 10. Typical hydraulic conductivity values (Freeze and Cherry 1979) for the bedrock aquifers fall below the range for a rating of one (Table 1). Typical values for the two sedimentary aquifers in the northwest corner of Electoral Area C were also fall within a rating of one. 3.2.8 DRASTIC Vulnerability Rating Figure 4 illustrates the preliminary map of total vulnerability of Electoral Area C. Vulnerability ranges from 35 to 171 of a possible 230. Generally, the sand and gravel aquifers in the valley bottom are more susceptible to contamination than the igneous and metamorphic aquifers in the valley uplands. This is mainly controlled by the shallow depth to water in the valley bottom, along with high ratings assigned to aquifer media and aquifer conductivity. 3.3 Discussion and Ongoing Work Depth to water and impact of the vadose zone are the most heavily weighted inputs to the DRASTIC model. Thus, it is important to characterize their spatial variability as best as possible. The use of different variograms and control points for cokriging the water table will be

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Figure 4: Relative intrinsic aquifer vulnerability in the Greater Oliver area (Electoral Area C). explored; as will alternate methods of estimating water table depth in the uplands. The saturated hydraulic conductivity of some soils in Electoral Area C were measured with a Guelph permeameter in August 2006. These values will be compared to conductivity values thought to be representative in the preliminary vulnerability mapping. Net recharge values will also be investigated further. Although, it may not be necessary to obtain exact values of recharge because of the range associated with each rating. Irrigation will be accounted for, and could increase the rating slightly in these areas. The DRASTIC method of vulnerability mapping does not take into account areas of recharge and discharge. The vulnerability of a discharge area may be lower than predicted due to an upwards hydraulic head gradient. Conversely, upland areas rated less vulnerable may be more vulnerable if in a recharge area. A concurrent project in the Okanagan will examine the contribution of recharge from the uplands into the valley bottom, which may be useful in to refine the vulnerability maps further. The inclusion of the fractured media characteristic in DRASTIC-FM (Denny et al. in review) may also affect the vulnerability of the upland areas. Bedrock fractures can create permeable zones, increasing recharge, and thus vulnerability. The use of DRASTIC-FM for Electoral Area C and the entire Okanagan will be considered. 3.4 Validation of Vulnerability Maps Nitrate is a conservative species commonly found in groundwater. Nitrates occur naturally in soil and groundwater, but can become a contaminant in high concentrations. Elevated nitrate concentrations are a

health concern primarily in infants, where “blue baby” syndrome can result from nitrogen replacement of oxygen in the blood. Nitrates are introduced into groundwater from fertilizers, livestock waste, and septic systems. The use of nitrates as a relative measure of the vulnerability of an area has been used in many studies (Wei 1998; Ceplecha et al. 2004; Holman et al. 2005). Wei (1998) found a positive correlation between relative nitrate concentration and relative aquifer vulnerability. Existing nitrate data and field data (August 2006) collected in the Oliver area will be used to compare relative nitrate concentration to vulnerability. This comparison will aid in the evaluation of the validity of the vulnerability maps. 3.5 Alternate Vulnerability Models - AVI There are many types of aquifer vulnerability models developed by different governments (Van Stempvoort et al. 1992). Two types of models used in Canada are DRASTIC, and Aquifer Vulnerability Index (AVI) developed by the Canadian Prairie Provinces Water Board in 1992 (Van Stempvoort et al. 1992). AVI contains many of the same assumptions used in DRASTIC including surface introduction of a contaminant and vertical percolation through the unsaturated zone with the same mobility as water. AVI requires less data than DRASTIC. Vulnerability is determined by the magnitude of the hydraulic resistance (c). Hydraulic resistance is calculated based on the thickness of each layer (di) above the water table and the layer’s hydraulic conductivity (Ki):

∑=i

i

K

dc [2]

The hydraulic resistance has units of time, and is a measure of the flux-time per unit head gradient for water percolating downwards to the aquifer (Wei 1998). The differences in vulnerability between AVI and DRASTIC will be compared for Electoral Area C. DRASTIC is favoured because of its use in other areas of BC. But, AVI is a simpler method requiring less data. The AVI method would be easy for municipalities to utilize for local vulnerability mapping in future sustainable development projects. 4. APPLICATION OF VULNERABILITY MAPS IN A

SUSTAINABLE COMMUNITY DESIGN PROCESS

Vulnerability maps represent an effective means of synthesizing complex geologic and hydrogeologic information for use by planners and policy-makers in developing resource management and growth management strategies. The Greater Oliver area,

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comprised of the Town of Oliver and its surrounding rural area, is participating in an initiative called Smart Growth on the Ground (SGOG) that works with communities to develop plans for growth that are smarter and more sustainable. The vulnerability maps developed for the south Okanagan will be used in the Pathways Land Use Allocation Model (LUAM). The LUAM will support the delineation of areas suitable for future growth based on constraints and indicators identified by the community.

4.1.1 The Smart Growth on the Ground Process Smart Growth on the Ground is a collaborative project between the Design Centre for Sustainability at the University of British Columbia, SmartGrowth BC, and the Real Estate Institute of BC. Smart Growth on the Ground uses inclusive design tools, extensive public consultation, and capacity building that engages the development community. The program helps to achieve more sustainable communities by creating tangible, built examples of smart growth (SGOG 2005). Greater Oliver was chosen as one of three pilot study communities in BC.; previous SGOG participants include Maple Ridge and Squamish. A core concept for the SGOG team is that a community can decide how population growth and subsequent development occurs, and the community can create liveable, smart growth choices for its future. To work towards this, the SGOG team acts as facilitators with a community to establish a vision, principles, goals and targets for smart growth. The SGOG process includes extensive consultation to identify community priorities for future growth; in Greater Oliver, the community was asked to envision their future in the year 2041. Supplemented with extensive research on best management practices and creative solutions, a major milestone in the SGOG process is a design charrette. A charrette is a design and planning event that takes place

over several days. The charrette allows all community decision-makers (municipal officials, developers and local residents) to work together to plan and design the housing mix, streetscape, commercial opportunities, transportation routes, trail networks and community character for the future. Water scarcity and water quality were identified as key priorities during the initial phases of the SGOG process in Greater Oliver due to the projected population growth coupled with agricultural (fruit crops, vineyards) and recreational activities that rely on water. 4.1.2 Land Use Allocation Model (LUAM) The modeling process integrates knowledge about the Greater Oliver region and growth management to highlight areas on the landscape that are consistent with community priorities, and are aligned with regulatory controls. The Pathways Land Use Allocation Model allocates growth to land area based on a set of criteria that are used to determine and prioritize the issues that constrain or drive growth. The process involves ranking and weighting the suitability of a given land area to receive future growth. The result is a model identifying overall suitability of a given location to receive new growth, based on community preferences and regulatory controls. Used together with future population projections and growth rates, the model allocates population based on the suitability.The LUAM criteria for Oliver were grouped into several classes, including water quality, land management practices, land cost, amenities, infrastructure, market proximity, natural hazards, and ecological. The specific criteria within each of these groups are outlined in Table 3. The use of the Oliver aquifer vulnerability map falls within water quality. Aquifer vulnerability is included among the criteria in the LUAM to guide appropriate land use policies that might compromise groundwater quality as the community’s residential or commercial sectors evolve over time.

Table 3: Land use planning criteria established during the Greater Oliver case study and used as inputs in the Pathways Land Use Allocation Model.

Criteria Grouping Criteria

Water Quality Aquifer vulnerability, community water supply, domestic water supply

Land Management Practices

Agricultural Land Reserve, parks and conservation areas, Crown land, First Nations lands, existing building structures, growth boundary

Land Cost Ratio of land value/building value, vacant land value

Amenities Sense of place, viewscapes, proximity to community services, proximity to job centres,

proximity to transportation hubs, proximity to recreation sites, proximity to parks and open space, proximity to trail networks, parks and conservation areas, riparian zone protection

Infrastructure Existing settlement, proximity to infrastructure, proximity to major transportation routes, utilities and services

Market Proximity Proximity to tourism centres, proximity to population centres, proximity to infrastructure

Natural Hazard Steep slopes, floodplains, fire hazard areas

Ecological Riparian zone protection, sensitive or critical habitat, wildlife corridors

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The LUAM is a spatial allocation model that ranks criteria based on its suitability to receive growth (i.e. residential or commercial growth); the rankings range from strongly encouraged for growth, to areas that are forbidden to receive growth within the model Rankings are defined during design exercises by planners or other discipline-specific experts such as hydrogeologists, ecologists and real estate professionals. During these planning exercises, a “goodness scale” between 0-9 is applied to each criterion. Within this scale, 0 represents criteria such as regions of “high” aquifer vulnerability, or sensitive habitat areas, where development is forbidden. A 9 represents criteria such as regions of low aquifer vulnerability, or locations in close proximity to transportation hubs, where development would be desirable. Relative weights are assigned during community consultation are then applied to each criteria group to establish their hierarchy within the overall sustainable community design. The LUAM for Oliver was created in ArcGIS and a commercial suite of ‘what-if’ scenario modelling and landscape visualization tools called CommunityVizTM. Each grid cell represents the cumulative ranking of all criteria outlined in Table 3 multiplied by the assigned weightings. LUAM outputs identify regions of desirable future development. The LUAM can also be used to evaluate proposed design solutions against the target indicators established for Greater Oliver during consultation. The Greater Oliver charrette took place in May 2006. It is anticipated that the outcome of this process will highlight the importance and utility of the Land Use Allocation Model. The LUAM is a robust factor for land use planning due to its ability to incorporate datasets such as aquifer vulnerability maps, and to explicitly reflect suitable areas for future growth based on land use policy and community criteria. Highly integrative, the LUAM provides a mechanism for complex geologic and hydrogeologic information to be considered within a land use planning and design context to support smarter and more sustainable community development. 5. ACKNOWLEDGEMENTS

This research was supported financially by the Natural Sciences and Engineering Research Council (NSERC) in the form a post-graduate PGS-M scholarship, the Canadian Water Network, and Natural Resources Canada. 6. REFERENCES

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Toews, M. (2006) Personal communication, Department of Earth Sciences, Simon Fraser University, Burnaby, BC, Canada

Van Stempvoort, D., Ewert, L., Wasswenaar, L. (1992) AVI: A method for groundwater protection mapping in the prairie provinces of Canada. Prairie Provinces Water Board, Regina, Saskatchewan.

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Wei, M., Allen, D.M., Scibek, J., Bishop, T., Ronneseth, K., Carmichael, V., and Hardy, R. (2003) Hydrogeologic Mapping and characterization of the Aquifer at Grand Forks, Southern British Columbia to Support Local Planning and Protection, Canadian Geotechnical Society/International Association of Hydrogeologists (IAH-CNC/CGS) Joint Conference, Quebec City, Quebec, October 24-27, 2004.

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