LAKES - Groundwater

Groundwater

Most of the Earth's freshwater is underground in void space in the saturated zone within bedrock

Void spaces

Pores, fractures

Percolation

Approximately 15% of precipitation recharges groundwater.

Critical to maintain groundwater

Conservation and protection

How much of the freshwater resources are in Canada

7%.

Watershed (surface water)

An area of land in which precipitation drains to a common point on a stream, river, pond, lake or other body of water (drainage basin)

Groundwater divide

A curve representing the water table ridge (descibed with contours of the groundwater level) the separates the flow domain in subdomains.

Aeration/Unsaturated/Vadose

zone = land surface to top of the phreatic zone

Capillary fringe

Regions in which water seeps/wicks up from vadose zone

Water table

Top of saturation zone

Saturated zone

Region in which space is filled with water

Aquifer

Layer of water-bearing material (permeable; supports springs). Geological formations that (1) stores, (2) transit, and (3) yields water. All depends on the geology: recharge, aquitarda, aquicludes, etc.

Aquitard

Layer that retards water flow (e.g., clay)—relatively impermeable

Unconfined (water table) aquifers

Influenced by atmosphere (need pump)

Confined aquifers

Under piezometric pressure because of "cap" (aquitard)

Spring

Exit point at which ground emerges from the aquifer and flows onto the top of the Earth's crust to become surface water

Well

Is a hole made into the ground to access water contained in an aquifer

Hydrodynamic Equilibrium

Discharge = recharge

Hydrodynamic Disequilibrium

discharge > recharge

Cone of depression/ascension

Active withdrawal of groundwater can have consequences by changing the slope of shape of the water table

Groundwater hydrology/geohydrology/hydrogeology

Deals with the distribution and movement of groundwater in soil and rocks of the Earth's crust

Groundwater flows

Perpendicular to equipotential lines

Epigean

Surface dwelling

Hypogean

Being, living or growing underground or below the surface

Stygophile

Surface-dwelling (epigean) species with incipient adaptation to the groundwater life and able to maintain permanent subterranean populations

Stygobite

Obligate groundwater-inhabiting species

Stygobiont/Stygofauna

Term for groundwater-dwelling organisms

Stygoxene

Species only occurring sporadically in groundwater habitats without permanent subterranean populations.

Estimated habitat

22.6-23.6 x 103 km³ in the upper 2 km of continental crust

Subterranean evolution

Loss of eyes, pigmentation, wings, water regulatory processes. Increase in appendage length of life span. Decrease in the number of eggs and respiratory metabolism

The range of higher taxa found

below ground does not reflect the above-ground faunal diversity

Copepoda, Isopoda, and Amphipoda

Crustacea are some of the most abundant, widespread, and taxonomically diverse groups in groundwater.

Truncated food web

The lack of basal trophic levels → opportunism and redundancy with convergent evolution and high rates of endemism

Stygobionts (dominant groups)

Cyclopid and harpacticoid copepods, ostracods, hermosbaenaceans, mysids, amphipods, isopods, syncarids, decapods, water mites, nematodes, gastropods, triclad turbellarians, and amphipods

Stygobionts (densely colonized)

by prokaryotes, microeukaryotes and viruses

Stygobionts (sporadic groups)

bacteria, protozoa, rotifera, cladocera, archiannelida, oligochaeta, gastrotricha, bivalvia, and insect larvae.

LNAPL

Light non-aqueous phase liquid

DNAPL

Dense non-aqueous phase liquid