B&C Groundwater fundamentals Flashcards

1
Q

Potential Energy

A

energy stored in a system

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2
Q

Groundwater flow

A

mechanical process
flow forces must overcome friction between porous media and fluid

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3
Q

in groundwater the main sources of potential energy

A

position (GPE), and pressure

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4
Q

unsaturated zone potential energy

A

due to attraction between soil and water (moisture potential)

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5
Q

Piezometer

A

a borehole only open at the bottom
tell us the pressure at the opening

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6
Q

isotropic

A

material properties same in all directions
k is scalar

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7
Q

work done per unit mass

A

=acceleration * distance

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8
Q

hydraulic potential to hydraulic head

A

divide everything by gravity

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9
Q

z

A

elevation head- from datum to bottom of piezometer

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10
Q

p/(g*rho)

A

pressure head - from bottom of piezo to top of water in piezo

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11
Q

homogeneous

A

same properties in every location of the unit

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12
Q

flow in an anisotropic medium

A

flow is deflected away from the gradient direction towards the direction with least flow resistance

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13
Q

Piezometric surface

A

connects all points to which water would rise if piezometers were installed
unconfined aquifer this is water table
hieght determined by the hydraulic head

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14
Q

Artesian well

A

Piezometric surface about ground surface

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15
Q

Flow direct to equipotential head lines

A

perpendicular in an isotropic homogen aquifer

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16
Q

Flow net

A

the network of equipotential lines and flow lines belonging to a specific aquifer

17
Q

flow net assumptions

A

homogeneous, isotropic, fully saturated aquifer & flow boundary conditions

18
Q

no flow boundary

A

flow parallel to boundary
equipotential perpendicular to boundary

19
Q

constant head boundary

A

flow perpendicular to boundary
equipotential are parallel to boundary

20
Q

effective stress (sigma e)

A

portion of total stress not borne by the fluid

21
Q

compressibility

A

strain/stress

22
Q

beta

A

compressibility of water

23
Q

alpha

A

compressibility of porous medium, rearrangement of grains

24
Q

compressibility is inversely dependent on

A

grain size

25
why is k aquitard < k aquifers
aquifers can transmit water quickly so if water pumped out head will drop quickly in aquifers compression much slower in aquitards
26
Transmissivity T
= bK amount of water that can be transmitted horizontally through a unit by the full saturated thickness of the aquifer
27
Ground water induced compaction
thick sequences poorly consolidated sediments with interbedded aquifers and aquitards
28
storativity values
very small <0.005
29
spring discharge controlled by
input events e.g. lots of rain
30
shape of hydrograph controlled by
flow through different pathways that have different K and velocities