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Preliminary Hydrogeological Characterization of The

Preliminary Hydrogeological Characterization of The

57ième CONGRÈS CANADIEN DE GÉOTECHNIQUE 57TH CANADIAN GEOTECHNICAL CONFERENCE 5ième CONGRÈS CONJOINT SCG/AIH-CNN 5TH JOINT CGS/IAH-CNC CONFERENCE

PRELIMINARY HYDROGEOLOGICAL CHARACTERIZATION OF THE , Christine Rivard, Martin Ross and Yves Michaud, Geological Survey of , Québec, Qc, Canada Tony Hamblin, Geological Survey of Canada, Calgary, AB, Canada John Drage, Nova Scotia Environment and Labour, Halifax, NS, Canada Amanda Blackmore and Timothy Webster, Centre of Geographic Sciences (COGS), Middleton, NS, Canada Claudio Paniconi, INRS - Eau, Terre et Environnement, Québec, Qc, Canada Christine Deblonde, Geological Survey of Canada, Québec, Qc, Canada

ABSTRACT A regional hydrogeological study in the Annapolis-Cornwallis Valley, Nova Scotia, is being undertaken within the framework of the Geological Survey of Canada Groundwater Program. The overall objective of this project is to characterize and quantify the groundwater resource within granular and fractured aquifers of this region (2100 km2). A comprehensive inventory of existing data led to the creation of databases. Preliminary analysis of these data allowed the development of a first 3D geological model, and the mapping of hydraulic properties and hydraulic heads. The main regional aquifer resides in the Formation, which underlies most of the Valley floor. The overlying Quaternary sediments mostly consist of till, ice-contact glaciofluvial and sandy proglacial sediments, whose thickness vary from 0 to 50 m. Reported transmissivities generally range from 10-5 to 10-2 m2/s, indicating that a good aquifer potential is available. The regional groundwater flow appears to be mostly controlled by the topography.

RÉSUMÉ Une étude hydrogéologique régionale dans la Vallée d’Annapolis-Cornwallis en Nouvelle-Écosse a été entreprise dans le cadre du programme sur les eaux souterraines de la Commission géologique du Canada. L’objectif général de ce projet consiste à caractériser et à quantifier l’eau des aquifères granulaires et fracturés de cette région (2100 km2). Un inventaire complet des données existantes a mené à la création de banques de données. L’analyse préliminaire de ces données a permis le développement d’un premier modèle géologique 3D et la cartographie des propriétés et charges hydrauliques. La principale formation aquifère est la formation géologique de Wolfville, qui tapisse le fond de la vallée. Les dépôts quaternaires sont principalement composés de till, de sédiments fluvioglaciaires et de sables proglaciaires, dont l’épaisseur varie de 0 à 50 m. Les transmissivités varient généralement entre 10-5 to 10-2 m2/s, indiquant la présence d’un bon potentiel aquifère. L’écoulement régional de l’eau souterraine semble surtout contrôlé par la topographie.

1. INTRODUCTION quantify the groundwater resource within granular and fractured aquifers. This project will assess aquifer The Annapolis-Cornwallis Valley is a long narrow lowland properties, hydrodynamic conditions, and groundwater extending from the Minas to the Annapolis basins along the characteristics, so as to provide valuable information to south shore of the in Nova Scotia. The Valley support management programs. is about 100 km long and 10 to 15 km wide, and lies within the North and South mountains. The rich and fertile soils, as well as its micro-climate, make the Annapolis-Cornwallis 2. CHARACTERISTICS OF THE STUDY AREA Valley one of the three key regions in Canada for commercial fruit production, along with the Okanagan Valley 2.1 Physiography and hydrography and the Niagara Peninsula. The Annapolis-Cornwallis Valley is flanked to the south by Population growth, intensive farming, changes in land use, the granite rocks of the South Mountain and to the north by and recent droughts have put high pressure on water the basaltic North Mountain cuesta. It comprises 6 primary resources in the Valley. Limited surface water supplies and watersheds: Annapolis, Cornwallis, Habitant, Canard, its poor quality have made groundwater increasingly Pereaux and Gaspereau. The drains almost appealing. Little is known, however, about the groundwater 1600 km2, while the other 5 rivers drain about 1070 km2. resource and its properties. The only significant regional The Gaspereau watershed is not included in this study, hydrogeologic report for the Valley was published more than since its population is small and few environmental 35 years ago (Trescott, 1968). problems have been reported. Figure 1 shows the location of the study area. The small watersheds of Habitant, Canard The current Annapolis-Cornwallis Valley Aquifer Study has and Pereaux (totalling 125 km2), all located at the north- been undertaken within the “Assessment of Regional eastern extremity of Kings County, have been included in Aquifers: Towards a National Inventory” framework of the the Cornwallis watershed in this figure. These sub- Geological Survey of Canada Groundwater Program. The watersheds are separated from each other by low ridges. overall objective of this project is to characterize and

Session 1B Page 5 evacuated either through the Annapolis River to the or through the to the . Both basins connect to the Bay of Fundy.

2.3 Population and land use

The Valley is rural, with towns and villages concentrated predominantly along the rivers. The eastern end of the Valley is the most urbanized. From the 2001 population census, a total of 84 183 residents lived within the borders of Kings and Annapolis Counties (Nova Scotia Statistics Division, 2004), representing 8.9% of the province’s population. Kings County had one of the highest population growths in Nova Scotia over the last years (7.8% over the 1991-2001 period), while the population in Annapolis County declined (6.7% for the same period; Timmer, 2003).

The region’s economic base includes agriculture, , Figure 1: Location of the study area tourism, and technology. One third of the provincial income from agriculture comes from Kings County (KCEDA, 1998). Elevations of the South and North Mountains rarely exceed Major products include: orchard fruits (mostly apples), 250 m asl, and river banks heights in the Valley vary from 0 cranberries, blueberries, chickens, vegetables and potatoes, near the basins to 40 m at the watershed divide. Because of turkeys, and hogs. the topography, only a small portion of the North Mountain is included in the study area while a very large portion of the South Mountain is encompassed in the studied watersheds. 3. DATABASES AND DATA DISSEMINATION Although the study area comprises an impressive 1682 km Over a hundred documents including reports, maps, of rivers, the Valley is not very well drained and contains scientific papers, and theses were compiled (and often 157 small to moderate lakes and reservoirs (covering 68 digitized) and structured into databases. Databases from km2). Wetlands throughout the Valley, especially along the two Nova Scotia Departments, Environment and Labour main rivers (i.e. Annapolis and Cornwallis Rivers) and the (NSEL) and Natural Resources (NSDNR), have also been coast of the Minas Basin have been extensively altered by obtained. Targeted information primarily consisted in well dyking and infilling. It is estimated that 80% of the original log descriptions, well characteristics (depth, yield, static salt marshes have been dyked or filled to create agricultural water level, etc.), weather and hydrological data, water lands (KCEDA, 2000). Even so, numerous bogs, ponds and chemistry data, as well as pump test results and data marshes are still present and provide excellent habitats for related to monitoring wells. Geotechnical and well data have wildlife. Wetlands currently represent 3% of the study area. also been obtained from National Defence (Greenwood military base). Five dataloggers have been installed to 2.2. Climate complement the provincial monitoring program so as to record daily groundwater levels. The Valley’s topography plays a major role in the climate conditions, with the North and South Mountains funnelling A web site (http://www.cgcq.rncan.gc.ca/annapolis/) was winds through the Valley and protecting it from weather created to provide data access to all stakeholders. Through blowing in directly off the Bay of Fundy and the Atlantic the web, participants can enter new observations and can Ocean (Timmer, 2003). Local climatic conditions within the also access, query, visualise, and edit existing data. The Valley are heavily influenced by proximity to the Annapolis information can further be integrated into a GIS and Minas basins and by topographic elevations. (Geographical Information System) for statistical and spatial analysis and map representation. The information gathered Sixteen weather stations, which data span over 3 to 96 so far is divided into four categories: 1) Project information years, provide annual precipitation varying from 1127 to (contact information and publications), 2) Field data (field 1400 mm, with an average of 1200 mm within the Valley data collected during the summer campaigns), 3) Compiled proper. Between 15 and 25% of this precipitation falls as data (metadata and databases), and 4) Maps. snow on average. Monthly average temperatures generally range from –5 to +19oC, with more than 200 frost-free days. Precipitation in the Valley falls mostly during the fall and 4. GEOLOGICAL CONTEXT winter, with precipitation levels peaking in December and January. The driest months are June and August. Surface 4.1 Bedrock runoff likely represents a significant component of the hydrologic budget. Indeed, runoff waters include a collection The Triassic/ rocks of onshore are of waters from the abrupt side of the North Mountain cuesta, related to the early stages of rifting and drifting that led to the Valley itself and a large part of the South Mountain. This the opening of the proto-. They water is drained to the bottom of the Valley, and is mainly

Session 1B Page 6 unconformably overlie a variety of Paleozoic rocks which The Blomidon Formation, present along the length of the themselves relate to earlier collisional and extensional Valley on the northern side, forms the flank of North phases (Greenough, 1995; Wade et al., 1996). Mountain. This formation is remarkably homogeneous, comprising evenly bedded red siltstone and mudstone, with Paleozoic minor fine sandstone. It could be classified as a “variable” or poor aquifer. There is again evidence of an overall fining- Paleozoic rocks form the South Mountain highland and the upward trend. Deposition occurred in an arid /playa basement beneath Triassic rocks in the Valley. These setting. It conformably overlies the Wolfville Formation and include the Meguma and the Horton groups, encountered conformably underlies the North Mountain Formation. directly under surficial deposits in some areas of the Valley. Thicknesses up to 363 m are known and the strata dip The Meguma Group’s youngest unit, the Halifax Formation 5oNW (Crosby, 1962; Smitheringale, 1973). The Blomidon (Lower Ordovician), covers a large region in the south- Formation is assigned a Late Triassic age. eastern part of the study area and is composed of interbedded slate, siltstone and quartzite (Trescott, 1968). In The North Mountain Formation corresponds to a series of the eastern part of the valley, the Meguma Group is tholeiitic flows, whose number varies from seven near unconformably overlain by the Horton Group, which consists Middleton to sixteen near the Minas Basin (Trescott, 1968). in its upper part of shale with interbedded grits and Columnar jointing is very well developed in many areas. sandstones. Strata are lenticular and cross-bedded, typical and various forms of are common. Coastal of the Maritimes Basin units. Middle-Late outcrops are generally good. Thicknesses up to 427 m are Devonian granitic and metasedimentary rocks are dominant recorded and the strata dip 3-5oNW (Crosby, 1962). in the South Mountain highland. Radiometric dates indicate an Early Jurassic age.

Mesozoic 4.2 Quaternary

The Mesozoic rocks of the Valley include the Triassic Fundy The Quaternary geology and geomorphology of the Group, underlying the Valley proper and forming the North Annapolis Valley present a high degree of diversity involving Mountain. In Nova Scotia, the Fundy Group comprises, in the major depositional systems of glacial settings. Their ascending order: the Wolfville, Blomidon, North Mountain, interactions often result in a series of genetically-related Scots Bay, and McCoy Brook formations, deposited in a contemporaneous or time-transgressive deposits partly half-graben fault-bounded basin. The Scots Bay and McCoy overlying other deposits of different origin and age. Surficial Brook formations however are not found in the study area sediments of the Annapolis-Cornwallis Valley were mapped and are therefore not described here. In the Annapolis- to a 1:500 000 scale (Stea et al., 1992) and to a 1:63 360 Cornwallis Valley, rocks of the Fundy Group outcrop along scale (1 mile: 1 inch, Trescott, 1968). the North Mountain and near the Minas Basin. Glacial dynamics The Wolfville Formation represents the most important bedrock aquifer of the Annapolis-Cornwallis Valley. This The Annapolis Valley records evidence of complex formation, which underlies most of the Valley floor, Wisconsinian glacial dynamics and deglacial history. Stea comprises reddish thickly bedded medium to coarse grained and Mott (1998) presented a glacial dynamics model arenitic to subarkosic sandstone, with subordinate pebbly consisting of four ice flow phases. The earliest ice flow was and conglomeratic beds whose clasts are derived from the towards the southeast (Caledonia Phase), and was followed adjacent metamorphic and granitic highlands. The Wolfville by a southward ice flow (Escuminac Phase). Later, the Formation is remarkable for its heterogeneity. It is an development of an ice divide over southern mainland Nova interbedded and intertonguing complex of crudely-stratified Scotia (Scotian Ice Divide) resulted in northwestward ice rocks of continental origin, typically in lenticular beds flow over much of the Valley (Scotian Phase). A late (Crosby, 1962; Taylor, 1969). Large-scale cross bedding is westward ice flow event is also recorded in the Valley and present in some locations. Consequently, its composition represents another significant glacial dynamics shift or a may vary widely from place to place. readvance from an ice lobe in the eastern part of the Valley (Chignecto Phase). A few striation sites indicating the age Deposition occurred in alluvial fan, fluvial, and aeolian relationships between the different phases are found mainly environments, and an overall fining-upward succession is in the North Mountain and South Mountain. In the lowland, evident (Tanner, 2000). It unconformably overlies the Lower outcrops are very rare but the study of landforms and and Upper Paleozoic rocks which form the deformed sediment characteristics provide a mean to analyse the basement in the area and thicknesses up to 833 m have impact and, in some cases, the extent of the different been reported (Crosby, 1962; Taylor, 1969). Wolfville rocks phases. are assigned a Late Triassic age. The strata generally dip 5- 10o NW towards the Bay of Fundy. Offsets of a few metres Sediment distribution and composition have been reported along numerous NE/SW and steeply dipping normal faults and joints, although there is no Available data and analysis of previous work as well as evidence for a large, basin-bounding fault on the south side limited recent investigations suggest the presence of west- of the Fundy Rift. (Crosby, 1962; Smitheringale, 1973; trending glaciofluvial morphosequences consisting of ice- Wade et al., 1996). contact and proglacial deposits. Across the Valley and

Session 1B Page 7 starting from the east end, kames and eskers, and perhaps valley. This likely implies controlled deposition, reflecting kame terraces, grade into and are partly overlain by former subglacial, englacial, and supraglacial debris outwash plain and outwash fan sediments which are linked, concentrations, crevasse patterns and/or drainage systems. in a possible interfingering fashion, to more distal and thus Glaciolacustrine rhythmites have recently been found near fine-grained glaciolacustrine/glaciomarine sediments in the Coldbrook but their extent and paleogeographic significance Bridgetown area. The morphosequences of ice-contact and are still poorly understood. It could be related to a local ice- outwash sediments imply that the late glacial westward ice dammed lake or a more extensive lake that covered part of flow phase (Chignecto Phase) extended to the area of the eastern side of the Valley. Available data tend to Middleton. indicate a limited extent.

Till and glaciofluvial deposits, as well as fluvial deposits, 4.3 Geological model cover most of the valley. Till is the most widespread glacial deposit, but the largest mass of glacial materials may be of A preliminary 3D geological model was developed, glaciofluvial origin (Trescott, 1968). The till composition is integrating map information from Trescott (1968), and the result of the different ice flow phases briefly described constrained by borehole data and interpretation. above and is also related to the underlying bedrock lithology. Deposits are thinner in the upland areas (rarely The thickness map of Quaternary sediments is presented in exceeding 10 m), and thicker in the valley (up to 20 m). Figure 2. Three potential buried NE-trending valleys have They can however reach 60 m in some bedrock been identified between Berwick and the Minas Basin, with depressions. Most of the surficial sediments were deposited depths varying from 15 to 60 m. However, the subsurface during the last glacial/deglacial episode. distribution and thickness of surficial deposits is poorly known at this stage and the thickness is likely In particular, the middle and eastern portion of the Valley is underestimated due to low borehole density, especially in generally covered by ice proximal/ice contact sandy the western portion of the Valley. These depressions should sediments, but some varved clays were observed during a contain sand and gravel, and could hence represent a non field trip. Their extent must be determined. Ice contact negligible aquifer potential. deposits are also present along secondary depressions near the Minas Basin, in many of the tributary valleys along The bedrock model was constructed using outcrops and South Mountain and scattered along North Mountain borehole data (137) from Trescott’s report (1968) as well as (Trescott, 1968). In general, the sediments are sandier and lithologic logs (100) from precisely described wells from the better sorted in the centre of the valley, whereas gravel and NSEL database. Some of these wells were located with fair boulders are found along the flank of the South Mountain precision using information contained in the original reports. (Trescott, 1968). An extensive outwash plain occupies much A DEM of the surface topography was used as a soft of the central part of the valley between Berwick and constraint. The preliminary 3D model is shown in Figure 3. Lawrencetown. West from Wilmot, outwash commonly overlie estuarine deposits of silt and clay (Trescott, 1968). Triassic units of the 3D model are dipping towards Outwash sediments usually consist of well stratified and northwest at an angle generally ranging from 3 to 7 degrees, cross-bedded fine to coarse sand. Clay-covered areas are which is within the reported range for these units (see relatively large west of Middleton. The ends of the valley are above). However, internal dip and structures are not dominated by intertidal sediments. modelled in the Horton Group and Lower Paleozoic rocks are undivided. The modeled vertical thickness of the As is often the case, eskers appear to be controlled by Wolfville Formation range from 0 to about 1150 meters depressions in the bedrock. Available data indicate that till is under the North Mountain. However, the geometry is mainly frequently lacking along these depressions, suggesting that inferred and extrapolated and is affected by the preliminary melt water activity eroded most of the pre-existing glacial modeling process itself. For example, the modeled sediments along these narrow conduits. Kames and other thickness of the Wolfville Formation is controlled by a set of ice-contact deposits are closely associated spatially with constraints and by the geometry of the underlying units eskers, forming complex and sometimes large and which are subject to modifications in future versions of the continuous glaciofluvial ridges in the eastern part of the model. Folds and faults are not yet represented.

Figure 2: Quaternary sediment thickness distribution

Session 1B Page 8 the grains by secondary (Trescott, 1968). Therefore, variable aquifer quality and conditions are encountered throughout the study area. According to Trescott (1968), water is primarily circulating trough intergranular pores spaces and only secondarily through joints. This hypothesis is still to be verified.

The Blomidon Formation, composed predominantly of fine- grained rocks (siltstone and claystone), can usually only yield small amounts of water, primarily through joints (Trescott, 1968). Occasionally, thin, interbedded sandstones and/or more frequent fractures are encountered, which will yield more water to drilled wells. However, this formation can act, regionally, as a thick sealing aquitard for the multiple aquifers of the Wolfville Formation.

Quaternary sediments

Glacial sediments of the Valley appear to be generally made of sand and gravel, but they tend to have a wide range of particle sizes due to highly variable meltwater flow conditions associated with glaciers. Outwash plain sediments are usually better sorted than in ice-contact deposits. Tills present different facies due to changes in glacial dynamics during deposition, but the nature of the underlying bedrock lithology is usually the predominant controlling parameter. Since sandstone is the most widespread rock over the valley, the till may be generally sandy. Figure 3: Preliminary 3D geological model The porosity and permeability of these deposits can thus be highly variable because of internal heterogeneity. 5. HYDROGEOLOGICAL CONTEXT Nevertheless, these deposits frequently contribute significantly to the recharge and may also locally constitute 5.1 Hydrostratigraphic units of most interest good aquifers. The major limiting factor is the limited saturated thickness. The largest granular aquifers should be The main bedrock aquifers occur in the Wolfville Formation found in buried bedrock valleys in the eastern portion of the and, to a lesser extent, in the Blomidon Formation. Other Valley (see Figure 2). These aquifer units are probably geological formations, such as the North Mountain and connected to underlying glaciofluvial and fractured rock those of the Horton Group, can provide good yields only on aquifers. a local basis, depending on their fracturing, jointing, and weathering, but are not considered good aquifers. They are 5.2 Hydraulic properties thus not described in this section. Sand and gravel deposits can constitute good aquifers in some areas of the Valley, To draw a preliminary portrayal of the hydraulic properties of depending on their saturated thickness. Tills cannot provide the Valley, 92 transmissivity values and 18 storage significant yields. However, they have a key role in this coefficient values are currently available. Wells were initially hydrogeological system, as they allow aquifers to recharge. located using the grid system of the Province (precision of 1 km2). Some well locations were improved, although Triassic bedrock approximately 20% still have duplicate coordinates. The great majority of these productive (high capacity) wells are o Due to the gentle northward dip of 5-10 of all Fundy Group located in the bedrock. Their depths are highly variable, with strata in the Bay of Fundy area, all stratigraphic intervals an average of 55 ± 35 m. Only 20% are less deep than 20 represented in the Triassic occur at surface somewhere in m. the study area. In the Wolfville Formation, good water- bearing sandstones and/or conglomerates may be Hydraulic properties exhibit large variations, as is to be penetrated almost anywhere within the boundaries of the expected in fractured rocks. Figure 4 shows that formation (Trescott, 1968). Nevertheless, the heterogeneity transmissivities generally range from 10-5 to 10-2 m2/s, of the rock of these formation, resulting from the regional indicating that a relatively good hydraulic capacity is dip, lateral discontinuity of the sub-units, and variable available in the Valley. Reported storage coefficients are lithologies, control the circulation of groundwater through the usually smaller than 10-3. The transmissivity data have Triassic rocks. In addition, movement of the water is often shown no correlation, most likely because not enough data limited by the poorly sorted sediments and cementation of pairs are available for a given range. Storage coefficients

Session 1B Page 9 are too scattered over the region to allow the building of a assuming that the granular and the bedrock aquifers are variogram. hydraulically connected and that a similar uncertainty can be attributed to each data source. This map, presented in Figure 5, was produced through kriging, using a spherical variogram with a correlation length of 25 km. The water levels measured in wells located in the study area vary from artesian flowing conditions to depths that can reach more than 50 m. The groundwater level depth (from the surface) is on average (median) 4.6 m. The regional groundwater flow is mostly controlled by the topography.

5.4 Hydrologic budget: water use and recharge

Groundwater is the primary source of drinking water for municipal and rural residents. Indeed, 99% of the Valley residents obtain their drinking water from groundwater (KCEDA, 2000). The move to reliance on groundwater is a relatively new phenomenon, with several towns and villages switching from surface water to groundwater sources within Figure 4: Spatial distribution of the transmissivities. Values the last decade. are classified into three ranges. A circle may represent either a single value or a geometrical mean of several The largest water use sector during the growing season is values located in a close area (within 1 km). agriculture. However, the great majority of irrigation demands are supplied by surface water. It is estimated that The bedrock aquifers appear to be generally confined or 80% of stream water is taken every summer for irrigation semi-confined, due to overlying fine-grained rock strata and (KCEDA, 2000). Since the demand for irrigation peaks sediments such as glaciomarine and intertidal deposits. during the months with the lowest streamflows, it can have a Nevertheless, aquifers of the bedrock and granular units significant impact on water resources. Year round appear to be hydraulically connected at the regional scale. management of water allocation thus poses challenges for Further investigations still have to be performed to study the municipal and provincial authorities. According to AGRA surface water and groundwater interactions. Earth and Environmental Limited (2000), demands exceed supply in the watershed, and 25%, 40% and 5.3 Groundwater levels 95% of the sustainable supply are used in the Annapolis, Cornwallis, and Pereaux watersheds, respectively. In many The preliminary piezometric map was obtained using all areas, residents are experiencing dry wells (KCEDA, 2000). data (9500 wells covering many years and seasons),

Figure 5: Piezometric map

Session 1B Page 10 The available information on well yields has allowed us to water shortages (1 to 18% of the calculated aquifer establish an approximate picture of the groundwater usage recharge). However, local, or at least sub-watershed, within the Valley. Only the high capacity wells are likely to studies should be performed to have a better idea of the provide an accurate yield since a long-duration pump test actual situation. was usually performed in these wells. As a result, this map Pereaux Habitant simply provides an indication of the hydraulic capacity of the 2 643 31 268 various geological formations. The spatial distribution shows Canard that most productive wells are found in the eastern part of 31 792 the Valley, where most industries, schools, and large farms are located. The yields in Figure 6 were classified into three categories, according to their values. The average yield reported in the database (median for 9600 wells) is 0.61 l/s. 185 873 Most wells (75%) have a yield smaller than 1.1 l/s. Only Annapolis 4.1% have a yield larger than 3 l/s, which is considered the upper limit for residential wells. Cornwallis

151 974 m3/d

Figure 7: Pie chart of groundwater demands for each sub- watershed (in m3/d)

5.5 Water quality

In the Annapolis-Cornwallis Valley, water pollution is of great concern, especially for nitrates, bacteria, and pesticides, as a large part of the land is devoted to agriculture. Besides farming related activities, concerns are mostly related to: poorly constructed or maintained septic systems, removal of riparian vegetation by agricultural and forestry operations, and a lack or malfunction of municipal Figure 6: Spatial distribution of groundwater yields sewage treatment plants (Timmer, 2003). Levels of nitrogen and fecal coliform in rivers that exceed limits for drinking, An indication of the hydraulic capacity can also be obtained irrigation, and even recreational activities are commonly using cumulative frequency graphs of the specific capacity reported throughout the Valley (Timmer, 2003). Currently, values (Q/s, where Q is the pumping rate and s is the total the town of Wolfville and other small harbour towns drawdown). However, less than a hundred values are discharge raw sewage into the Minas Basin (KCEDA, 2000). available for the Valley, because the NSEL well log database does not include this parameter. The average Some groundwater quality problems (mostly nitrates) have specific capacity was found to be 0.25 l/s/m, with 8% of the also begun to occur and will likely increase in the following wells having a value larger than 5 l/s/m and 4.5% larger years. However, current conditions indicate that than 10 l/s/m. groundwater within the bedrock is generally of good quality. This water is mainly of the calcium bicarbonate type and A water use survey of the Valley (MacPherson, 2004) has slightly alkaline. Natural occurrence of some elements (such indicated, using available data from 4 recent reports (2000- as and ) may be a problem in some areas. 2003), that the total groundwater demand for the study area Groundwater in bedrock has usually a higher was comprised between 31 000 and 404 000 m3/d, content, alkalinity and hardness than the water from surficial depending on the method of calculation used. These deposits. numbers are based on the fact that most groundwater demands come from domestic, institutional, and municipal, as well as industrial and commercial sectors. These 6. FUTURE WORK numbers therefore exclude irrigation demands. The pie chart of Figure 7 illustrates the maximum groundwater Field work will be carried out to verify the consistency of the demand distribution (in m3/d) as a function of the sub- glaciofluvial morphosequence interpretation. The nature of watershed. the transition and/or stratigraphic architectural relationships between the permeable glaciofluvial sequence and the more Preliminary base flow calculations using 5 gauging stations impermeable glaciolacustrine/glaciomarine sediments will have shown that recharge should be on the order of 385 also be investigated, especially at both ends of the Valley. mm/y. Recharge would then represent approximately 30% These fine-grained sediments can indeed play a significant of the precipitation. Using the aforementioned groundwater role in the regional hydrogeology, by impeding recharge and demand range, the regional budget does not indicate overall protecting aquifers from surface contamination. In addition,

Session 1B Page 11 areas with significant thickness of sand such as buried Crosby, D.G. 1962. Wolfville map-area, Nova Scotia (21 H valleys and depressions will be further studied. 1). Geological Survey of Canada, Memoir 325, 67 pages.

The possibility of a connection between surficial sediments Greenough, J.D. 1995. Mesozoic Rocks. In H. Williams and fractured rocks and, perhaps, fault systems, along (ed.), Geology of the Appalachian-Caledonian Orogen in certain depressions, will also be examined. If fault systems Canada and Greenland. Geological Survey of Canada, are present on both sides of the valley it would significantly Geology of Canada, no. 6, pp. 567-600. change the bedrock conceptual model. KCEDA. 2000. A study and review of sustainability Further analyses and additional data will also allow the 1) indicators, Quality of the Environment report for Kings estimation of the aquifer recharge with various methods, 2) County. Nova Scotia. Kings Community Development improvement of the understanding of the hydrodynamics Agency, 32 pages. within the Valley, 3) completion of the geological and hydrogeological maps, 4) development of conceptual and KCEDA. 1998. A survey of perceptions and issues. Quality numerical models and 5) analysis of geochemistry data. of the Environment report for Kings County. Nova Scotia. Kings Community Development Agency, 57 pages.

7. CONCLUSION MacPherson, S. 2004. Kings County and Annapolis County groundwater survey, Nova Scotia Department of Agriculture With the rapid economic development of the Annapolis- and Fisheries, internal report, 18 pages Cornwallis Valley, water allocation and water quality maintenance are posing challenges to municipal and Nova Scotia Statistics Division. 2004. provincial authorities. Since surface water supplies have http://www.gov.ns.ca/finance/statistics/agency/index.asp. become insufficient within the Valley in the past years, groundwater has become the major source of water supply. Smitheringale, W.G. 1973. Geology of parts of Digby, The most important aquifers are found within the Wolfville Bridgetown and Gasperau Lake map-areas, Nova Scotia Formation, which covers almost all the Valley floor. The (21A/12, East Half; 21A/14, East Half; 21A/15, West Half). Triassic rocks consist of a sequence of interbedding of Geological Survey of Canada, Memoir 375, 78 pages. coarse and fine grained lithologies. Water quality and yields may therefore vary over short distances, both Stea, R.R. and Mott, R.J. 1998. Deglaciation of Nova Scotia: stratigraphically and geographically. Stratigraphy and chronology of lake sediment cores and buried organic sections. Géographie physique et This study will shed light on some of the important water quaternaire, vol. 52, no 1, pp. 3-21, 11 fig., 1 table. issues of the Valley and will seek to further our understanding of groundwater / surface water interactions, Stea, R.R., Conley, H and Brown, Y. 1992. Surficial geology the hydrologic budget, hydraulic properties, and Quaternary of the province of Nova Scotia. Nova Scotia Department of sediment deposition history in an effort to better support Natural Resources, Map 92-3, 1:500,000. water resources management in the Annapolis-Cornwallis Valley. Tanner, L.H. and Brown, D.E. 1999. The Upper Triassic Chedabucto Formation, Guysborough County, Nova Scotia: depositional and tectonic context. Atlantic Geology, v. 35, ACKNOWLEDGMENTS pp. 129-138.

The authors wish to thank all the project collaborators for Taylor, F.C. 1969. Geology of the Annapolis-St. Marys Bay their availability and continued support. They are: the Nova map-area, Nova Scotia (21A, 21B East Half). Geological Scotia Department of Environment and Labour, The Centre Survey of Canada, Memoir 358, 65 pages. of Geographical Sciences, the Nova Scotia Agricultural College, the University, Environment Canada, Timmer, D. 2003. Watershed characterization project. Agriculture and Agri-Food Canada, National Defence, the Guelph Water Management Group, University of Guelph, Clean Annapolis River Project and the Friends of the http://www.uoguelph.ca/gwmg/wcp_home/index.htm Cornwallis River associations and finally, T. Hennigar who has acted as an advisor. We also wish to thank Dr. Rivera Trescott, P.C. 1968. Groundwater resources and for his valuable comments. This paper is a GSC contribution hydrogeology of the Annapolis-Cornwallis Valley, Nova no 2004037. Scotia. Department of Mines, Memoir 6, 159 pages.

Wade, J.A., Brown, D.E., Traverse, A. and Fensome, R.A. REFERENCES 1996. The Triassic-Jurassic , eastern Canada: regional setting, stratigraphy and hydrocarbon potential. AGRA Earth and Environmental Limited. 2000. Water Atlantic Geology, v. 32, pp.189-231. Resources Needs of the Agricultural Industry in the Annapolis Valley, Nova Scotia. Final Report. Halifax, Nova Scotia: AGRA Earth and Environmental Limited.

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