Groundwater

Question 1

Aquifer

Answer 1

The temporary storage of infiltrating precipitation with slow release to lakes and streams

Question 2

Vadose Zone

Answer 2

Area close to the surface where pore spaces are filled with a mixture of water and air

Question 3

Phreatic Zone

Answer 3

Depth where all pore spaces are saturated

Question 4

Aquitards

Answer 4

Low porosity and conductivity, provide protection for aquifers from surface contamination

Question 5

Gaining stream

Answer 5

Water table above base of stream, baseflow recharges stream

Question 6

Losing stream

Answer 6

Water table below base of stream

Question 7

Perched aquifer

Answer 7

Infiltrating water becomes trapped and cannot flow out

Question 7

Seepage face

Answer 7

Aquifer-aquitard contact outcrops at cliff face, causes groundwater to seep out

Question 8

Artesian well

Answer 8

Water table level sits above ground surface, flows out of ground naturally

Question 9

Groundwater well

Answer 9

Hole drilled into ground to target an aquifer

Question 10

Well screen

Answer 10

Outer casing that allows water to flow into well while filtering out large particles

Question 11

Groundwater head

Answer 11

Level to which water would rise in an infinite straw that is open to just that aquifer

Question 12

Piezometric surface

Answer 12

Contours of constant head within an aquifer

Question 13

Dupoit-Forchheimer Flow

Answer 13

Parabolic head profile in an unconfined aquifer assuming steady state conditions

Question 14

Drawdown

Answer 14

Change in head compared to an original pre-pumped state

Question 15

Hantush-Jacob Solution

Answer 15

Semi-confined aquifer with leakage, modelled by extra parameter, c, characterising the hydraulic resistance of the confining layer

Question 16

Moench-Neuman Solution

Answer 16

Model of delayed yield in unconfined aquifers

Question 17

Well yield

Answer 17

Maximum volume rate over a specified time period that introduces a drawdown no larger than Hmax

Question 18

Calculating the drawdown due to more than 1 well

Answer 18

Use the principle of superposition since Theis solution is linear

Question 19

Pump test with lateral flow barriers or a recharge source

Answer 19

Place an image well to model the effect of the flow boundary/recharge

Question 20

Using an image well for a lateral flow barrier

Answer 20

Place image well at equal distance from the lateral confinement as the pumped well
Drawdown at observation well is the sum of the image well and the pumped well

Question 21

Pump rate changes from x to y from time a to b

Answer 21

Drawdown is the sum of head due to x till time b, and the head due to (y - x) for time (b - a)

Question 22

Wellbore skin

Answer 22

Transmissivity reduction due to water level dropping more than expected

Question 23

Rorabaugh Method

Answer 23

Step-rate test to quantify transmissivity reduction using estimates from a pumping test

Question 24

Driven well

Answer 24

Pipe with pointed steel tip driven into ground to break through pebbles and layers of hard material

Question 25

Drilled well

Answer 25

Drill rig used to excavate hole, then casing and screen is placed.

Question 26

Well casing

Answer 26

The tubular components used in the construction of water wells

Question 27

Well screen intake

Answer 27

For wells in unconsolidated formations, prevent the pump from being clogged with aquifer material

Question 28

What is the maximum desirable screen entrance velocity related to?

Answer 28

Hydraulic conductivity of aquifer material

Question 29

Well screening for confined aquifers

Answer 29

Entire thickness of aquifer

Question 30

Well screening for unconfined aquifers

Answer 30

Lower one-third to one-half of the saturated thickness

Question 31

Why are longer screen lengths preferable?

Answer 31

Higher pumping rates per unit drawdown

Question 32

Common groundwater pump

Answer 32

Vertical turbine pump

Question 33

Grouting

Answer 33

Protection between well casing and borehole to prevent polluted surface water from contaminating the aquifer

Question 34

Performance assessment of groundwater wells

Answer 34

Pumping rate per unit drawdown

Question 35

Goal of wellfield design

Answer 35

Meet total pumping demand using as few whiles as possible while being constrained to a maximum drawdown

Question 36

Time of travel

Answer 36

Distance from a well where it will take a certain time for contaminants/water to reach the well