Definitions Flashcards
(17 cards)
Transmissivity
Transmissivity = hydraulic conductivity*depth
T = Kb
Unit: m^2/s
Hydraulic conductivity
Measure of permeability, often defined as k
Unit: m/s
Storativity
Storativity is the amount of water per m^2 of water needed to change hydraulic head by 1m in a confined aquifer. Storativity depends on compressibility and total saturated thickness of aquifer.
Specific Retention
Specific retention is the volume of water retained divided/volume of rock.
Specific Yield
Specific yield is the amount of water needed to lower the hydraulic head by 1m in an unconfined aquifer. It is the drainable pore space, which is always less than the total porosity due to specific retention. Fractured systems have higher Sy than matrix systems
Porosity
void or pore space in a rock/total volume of rock
Permeability
Often called hydraulic conductivity, defined as k
Unit: m/s
Aquifer
An aquifer is a geological formation that contains water and allows the movement of water within it
Unconfined Aquifer
An unconfined aquifer has an unsaturated zone and a water table
Confined Aquifer
An aquifer that is overlain by a less permeable surface, no water table, just a piezometric surface
Hydraulic Head
The mechanical energy per unit weight of fluid.
Intrinsic Vulnerability
Depends on physical properties of aquifer rather than specific contaminants. Can be entire aquifer vulnerability or single source vulnerability such as a well.
Specific Vulnerability
Vulnerability of an aquifer to a specific contaminant (or activity)
Contaminant
A substance which, by its presence, reduces value or utility of medium (in this case water)
Radionuclides
Unstable elements that decay, give off radiation and are especially harmful if inside the body. E.g. Uranium, Strontium, Caesium
Organic Molecules
Molecules with C, H, sometimes N, S, O or P
Interflow
Sub surface flow that takes water away from groundwater supplies.
