groundwater

connection bwtn glacial deposits, water supply, waste disposal

deposits → locate, protect aquifers; identify groundwater contaminant migration pathways, located future waste disposal sites; understand what lies beneath the ground surface

groundwater

water beneath the surface of the earth, fills cracks, cavities, pore spaces

how does groundwater move

from area of recharge (saturated rock) to areas of discharge (streams/lakes), moving through sediments and rocks

aquifer

a rock or sediment that holds and

transmits enough water to be

useful as a source of water (e.g. sand, sandstone, gravel)

aquitard

a rocks or sediment with slow rates of water movement (e.g. clay, shale (liquified clay), till, lake muds); not a barrier, rather incredibly slow rate

porosity

volume of open space (pore space) within a body of rock or sediment, all space not occupied by solid material

permeability

measure of how readily fluids pass through material, required to be a good aquifers

how do we identify sediment?

looking for exposures along creeks, lakeshore bluffs, and in quarries; drilling cores; geophysical well logging, ground penetrating radar (GPR)

drilling cores

taking samples of subsurface sediment/rock (generally 5 inch casing w 4 inch core, removed in 5 ft lengths)

3-D block diagram

groundwater assignment

geophysical well logging

placing geophysical probes into walls to measure physical properties

what do geophysical probes measure?

gamma radiation (high in clay), conductivity, magnetic susceptibility

ground penetrating radar

radar waves used to image the changes in properties of subsurface materials (looks at boundaries); used for shallow investigations

types of glacial deposits in southern Ontario

tills, deltaic sands, lake muds (poor permeability)

glacial stratigraphy in southern Ontario

alternating layers of fine-grained sediments (tills, lake muds) and course grained sediment (sands, gravels), indicating a changing environment overtime (e.g. Scarborough Bluffs)

aquifers/aquitards in southern Ontario

aquifer = sand, aquitard = till and mud

permafrost

permanently frozen layer of soil beneath the surface of the ground

how much of Canada has permafrost

40%, but was 50% in the 70s-90s

where is permafrost common?

periglacial (cold climate) environments