Groundwater Hydraulics: Groundwater head & flow

Question 1

True or False
Fluid potential in a fluid flow through porous media is defined as the mechanical energy per unit mass of fluid.

Answer 1

True

Question 2

Fluid potential, denoted as ɸ, is calculated as gz + u^2/2 + ∫dP/ρ, where g represents _______, u is the velocity the fluid, and P is the pressure.

Answer 2

gravitational acceleration

Question 3

What does the hydraulic head, h, represent in fluid dynamics?
A) The velocity of the fluid
B) The pressure head plus the elevation head
C) The temperature gradient of the fluid

Answer 3

B) The pressure head plus the elevation head

Question 4

What does Darcy’s Law describe?

Answer 4

Darcy’s Law describes the flow of a fluid through a porous medium, quantifying the flow rate based on the hydraulic conductivity, the area perpendicular to flow, and the hydraulic gradient.

Question 5

True or False
According to Darcy’s Law, the flow rate q is directly proportional to the hydraulic gradient Δh/Δz.

Answer 5

True

Question 6

The hydraulic head in an observation well represents the average hydraulic head over the length of the _______ section of the well.

Answer 6

open

Question 7

Which device is used to directly measure the hydraulic head at a specific point in a groundwater system?
A) Dipper
B) Piezometer
C) Thermometer

Answer 7

B) Piezometer

Question 8

True or False
The water level in a piezometer always matches the water table level in unconfined conditions.

Answer 8

False

Question 9

A dipper used to measure hydraulic head in a well has a graduated tape and makes a sound when it touches _______.

Answer 9

water

Question 10

What is the purpose of the porous tip in a piezometer?

Answer 10

The porous tip allows water from the surrounding soil to enter the piezometer, enabling accurate measurement of the hydraulic head specific to that point.

Question 11

True or False
The hydraulic head is calculated as h = z_m − d_w, where z_m is the elevation to the top of the casing and d_w is the depth of the water.

Answer 11

True

Question 12

To measure the hydraulic head accurately, one must level in the casing to ensure the correct elevation of the top of _______.

Answer 12

casings

Question 13

How many piezometers are required to determine the direction of groundwater flow?
A) 2
B) 3
C) 4

Answer 13

C) 4

Question 14

What does the equation
h (t) = z_m − d_p + [P_p(t) − P_a(t)]/ρg describe?

Answer 14

It describes how the hydraulic head varies over time, accounting for the changes in pressure and elevation.

Question 15

True or False
The gradient of the hydraulic head can be calculated without assuming constant hydraulic conductivity in the location and direction.

Answer 15

False (It assumes constant hydraulic conductivity)

Question 16

The formula dh/ds = I = √(A^2 + B^2) is used to find the ______ gradient in an aquifer.

Answer 16

hydraulic head

Question 17

In steady flow within a confined aquifer, what is significant about the product
HK?
A) It represents hydraulic conductivity.
B) It is referred to as the aquifer transmissivity.
C) It indicates hydraulic head.

Answer 17

B) It is referred to as the aquifer transmissivity.

Question 18

True or False
In an unconfined aquifer under the Dupuit-Forchheimer assumption, there is a vertical head gradient.

Answer 18

False (The assumption is that there is no vertical head gradient, and flow is purely horizontal)

Question 19

The equation h^2-h_0^2 =0 W/K(Lx - x^2) + (h_1^2 - h_0^2)x/L describes the water table profile under _______ conditions.

Answer 19

steady flow in an unconfined aquifer with recharge

Question 20

What scenario does the model of two parallel ditches with vertical recharge illustrate in groundwater studies?

Answer 20

It models an unconfined aquifer with recharge and equal boundary conditions, showing the maximum water table height at the midpoint between the ditches.

Question 21

What is A in the question?

Answer 21

A = ∂h/∂x

Question 22

What is B in the equation?

Answer 22

B = ∂h/∂y

Question 23

How do you find direction of flow?

Answer 23

θ = arctan(A/B)

Question 24

What are the units of transmissivity?

Answer 24

L^2T^-1