PRINCIPLES OF GROUNDWATER FLOW & GROUNDWATER FLOW TO WELLS Flashcards
Groundwater possesses energy in __________, ____________, and __________ forms.
mechanical, thermal, chemical
What are the three 3 external forces acting on groundwater?
gravity, external pressure, and molecular attraction
A force resisting the fluid movement and acts tangentially to the surface of the solid.
shear stresses
A force resisting the fluid movement and acts perpendicularly to the surface.
normal stress
The internal molecular attraction of the fluid itself resists the movement of fluid molecules past each other This shearing resistance is known as the ___________.
viscosity
A device used to measure liquid pressure in a system by measuring the height to which a column of the liquid rises against gravity, or a device that measures the pressure
of groundwater.
Piezometer
The ___________ is equal to the sum of the elevation head and the pressure head.
total hydraulic head
Density variation to the head due to _______.
Salinity
The water level in the well filled with water coming from a point in an aquifer and which is just enough to balance the pressure in the aquifer at that point
Point-water head
The height of a column of fresh water in a well that is just sufficient to balance the pressure in the aquifer at that point
Fresh water head
Total mechanical energy per unit mass to be equal to the sum of the kinetic energy, elevation energy, and pressure
Force Potential
True or False. Total mechanical energy= force potential.
TRUE
True or False. As groundwater moves, it encounters no resistance between the fluid and the porous media.
FALSE. Frictional resistance
True or False. Groundwater is warmed slightly as it flows and mechanical energy is converted to thermal energy
TRUE
Slowly moving fluids are dominated by viscous forces. There is a low energy level and the resulting fluid flow ____________
laminar
In laminar flow, molecules of water follow smooth lines, called __________.
Streamlines
Relates the four factors that determine whether the flow will be laminar or turbulent.
Reynolds number
If R exceeds a value of __________ then it is turbulent flow
2000
True or False. Turbulence in ground water is difficult to detect The inception of fluid turbulent flow in groundwater has been reported at a Reynolds Number ranging from 60.
TRUE.
True or False. Experimentation has shown that Darcy’s Law is not valid when are such that the resistive forces of viscosity predominate. These conditions prevail when the Reynolds number is less than 1 to 10.
False. Valid only when ….
An imaginary line that traces the path that a particle of groundwater would follow as it flows to the aquifer
Flow line
In an ___________, flow lines will cross equipotential lines at right angles
isotropic aquifer
Steady flow conditions may be solved by graphical construction of a ________ which is a network of equipotential lines and associated flow lines.
flow net
Groundwater cannot pass a __________.
no flow boundary
___________ boundary represents an equipotential line
constant-head boundary
For unconfined aquifers, there is also a __________.
water table boundary
True or False. If there is recharge or discharge across the water table, flow lines will be at an oblique angle to the water table If there is no recharge across the water table, flow lines can be parallel to it.
TRUE
__________ are like contour lines on a map that trace lines of equal altitude. In this case the “altitude” is electric potential or voltage. They are always perpendicular to the electric field.
Equipotential lines
_______ also function to inject fluids into the ground
Wells
True or False. As means of groundwater management, wells are sometimes used artificially to recharge aquifers at rates greater than natural recharge
TRUE
True or False. During injection, there is a decrease in the head of the aquifer.
FALSE. increase
____________ is the change in hydraulic head observed at a well in an aquifer, typically due to pumping a well as part of an aquifer test or well test.
Drawdown
Will form in the aquifer around a pumping well as the water level declines.
cone of depression
The head is constant with time
steady state flow
Often observed following other flow regimes. The emergence of _________ in an infinite conductivity hydraulically fractured well.
Radial flow
This type of flow exists in the time period before the pressure transient has reached the boundaries of the reservoir (infinite acting time period).
Radial flow
____________ is conducted to evaluate an aquifer by “ the aquifer through constant pumping, and observing the aquifer’s “ response”(drawdown) in observation wells.
Aquifer test
True or False. Aquifer testing is a common tool that hydrogeologists use to characterize a system of aquifers, aquitards and flow system boundaries.
True
___________ is a particular type of aquifer test where water is quickly added or removed from a groundwater well, and the change in hydraulic head is monitored through time, to determine the near well aquifer characteristics.
Slug Test
A ____________ is a region in which the aquifer is
replenished
recharge boundary
A __________ is an edge of the aquifer, where it terminates,
either by thinning or abutting a low permeability formation, or has been eroded away.
Barrier boundary
