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The Lowland context covers most of the study area. This hydrogeological context integrates the complete succession of all the hydrogeological units: Capilano-Salish, Capilano, Vashon-Capilano, Vashon till, Quadra, Cowichan-Dashwood, Dashwood-Mapleguard, Lower Nanaimo Group, and Metamorphic and Intrusive Basement. This context includes downstream portions of Nile Creek, Qualicum River, Little Qualicum River and French Creek. Most of the hydrostratigraphic units are present within the Lowland hydrogeological context, except near the main rivers where the sequence has been extensively eroded by fluvial incision. Along river valleys most surficial units, particularly Quadra Sands, are not in direct hydraulic link with the rivers. Groundwater seepage zones are present along the incised slopes. Groundwater in seepage areas can reach rivers by surface runoff or by hypodermic or saturated flow through the permeable Capilano sediments present at the base of incised slopes, commonly as low terraces. These sediments can also play a role in moderating interactions between surface and groundwater due to their water storage capacity even if their spatial distribution is limited. |
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Physiography
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| Hydrogeological region | Cordillera |
| Hydrogeological context | |
| Relief | The regional topography ranges from sea level at the coast, up to 1819 m (Mount Arrowsmith). The coastal plain terrain is sub-horizontal with slopes lower than 6% except along incised rivers valleys (up to 20%). |
| Area | 230.00 km2 |
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Lithology
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| Description | In descending order, the geological units are: the Salish Sediments, the Capilano Sediments, the Vashon Drift, the Quadra Sand, the Cowichan Head Formation, the Dashwood Drift, the Mapleguard Sediments, the sedimentary rocks of the Lower Nanaimo Group, and the metamorphic and intrusive basement. This geological unit succession shows an aquifer and aquitard altering succession. |
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Aquifer
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| Aquifers | List of aquifers:
- Capilano-Salish
- Vashon-Capilano
- Quadra
- Dashwood-Mapleguard
- Lower Nanaimo Group |
Groundwater Information Network