Groundwater Flashcards

Front 1

stressors on groundwater quality

Back 1

increasing populations, extensive development, the use of pesticides, fertilizers, animal manure, and storm water runoff which
contains metals, nutrients, salts and other chemicals that can leach into groundwater basins.

Front 2

ground water

Back 2

water that is found underground in the cracks and spaces in soil, sand and rock.

Front 3

surface water

Back 3

any water above the ground surface including ponds, lakes, rivers, oceans, puddles, etc.

Front 4

what plans need to be made to protect groundwater quality

Back 4

land use development (e.g.,
residential and commercial), infrastructure needs (e.g., roads, wastewater treatment, etc.), the local
economy, and a good jobs-per-housing ratio.

Front 5

events that can threaten groundwater quality

Back 5

drought, water conservation and efficiency, pollution
prevention, recharge zones, storm water management, and future water needs.

Front 6

aquifer

Back 6

Groundwater is stored in--and moves slowly through--layers of soil, sand and rocks. Aquifers typically consist of gravel, sand, sandstone, or fractured rock, like limestone. These materials are
permeable because they have large connected spaces that allow water to flow through.

Front 7

saturation zone (saturated zone)

Back 7

The area where water fills the aquifer

Front 8

water table

Back 8

the top area of the saturation zone

Front 9

things that cause groundwater to rise or fall

Back 9

Heavy rains or melting snow may cause the water table to rise, or heavy
pumping of groundwater supplies may cause the water table to fall.

Front 10

well

Back 10

a pipe in the
ground that fills with groundwater. This water can be brought to the surface by a pump.

Front 11

artesian wells

Back 11

do not
need a pump because of natural pressures that force the water up and out of the well.

Front 12

how aquifers are replenished

Back 12

by rainfall or snowmelt

Front 13

how groundwater can be polluted

Back 13

Groundwater can be polluted by landfills, septic tanks, leaky underground gas tanks, and from
overuse of fertilizers and pesticides.

Front 14

uses of groundwater

Back 14

• 22% of all freshwater withdrawals
• 37% of agricultural use (mostly for irrigation)
• 37% of the public water supply withdrawals
• 51% of all drinking water for the total population
• 99% of drinking water for the rural population

Front 15

hydrologic cycle

Back 15

the water cycle

Front 16

precipitation

Back 16

form that water falls to earth in such as sleet, hail, rain or snow

Front 17

energy source of the water cycle

Back 17

sun

Front 18

evapotranspiration

Back 18

the combined processes of evaporation and transpiration

Front 19

when evapotranspiration is highest

Back 19

spring, summer

Front 20

runoff v. recharge

Back 20

runoff is water running over surface of land while recharge is movement of water down into soil

Front 21

infiltration

Back 21

the entry of water into the soil surface. The rate of infiltration is influenced by the physical characteristics of the soil, soil cover (i.e.
plants), water content of the soil, soil temperature and rainfall intensity. The terms infiltration and
percolation are often used interchangeably

Front 22

percolation

Back 22

the downward movement of water through soil and rock. Percolation occurs beneath the
root zone.
The terms infiltration and percolation are often used interchangeably

Front 23

inflow and outflow of water cycle

Back 23

inflow is anything that adds water to cycle (percolation, infiltration)

outflow is anything that removes water (discharge to a stream)

Front 24

connection between ground water and surface water

Back 24

must be considered a single resource because they interact at many places in landscape

Front 25

bank storage

Back 25

A type of interaction between ground water and streams that is a rapid rise in stream stage when water moves from the stream into the streambanks causing inflow to groundwater.

Front 26

saturated zone

Back 26

the voids in the saturated zone are completely filled with water. Water in the saturated zone is referred to as ground water. The upper surface of the saturated zone is referred to as the water table. Below the water table, the water pressure is great enough to allow water to enter wells, thus permitting ground water to be withdrawn for use.

Front 27

unsaturated zone

Back 27

the voids--that is, the spaces between grains of gravel, sand, silt, clay, and cracks within rocks--contain both air and water. Although a considerable amount of water can be present in the unsaturated zone, this water cannot be pumped by wells because it is held too tightly by capillary forces. The upper part of the unsaturated zone is the soil-water zone.

Front 28

hydraulic head

Back 28

which is the sum of elevation and water pressure divided by the weight density of water. Describes potential energy in ground-water flow systems.

Front 29

piezeometer

Back 29

a well that has a very short screen so the water level represents hydraulic head in only a very small part of the ground-water system

Front 30

contamination from surface to ground water

Back 30

streams that discharge to groundwater can introduce contamination; shallow GW is most susceptible due to close proximity to land surface

Front 31

contamination from ground to surface water

Back 31

contaminated aquifers that discharge to streams result in long term contamination of surface waters

Front 32

source of all freshwater in hydrologic cycle

Back 32

precipitation

Front 33

ground water recharge

Back 33

infiltration of precipitation through unsaturated zone

Front 34

flow path of recharge

Back 34

occur in the uppermost unsaturated zone; can be feet to miles long; water may take years to millenia to travel flow path

Front 35

soil particles and permeability

Back 35

sand = highest permeability
silt = medium
clay = poorest or slowest

Front 36

soil particles (relative size)

Back 36

sand = largest (size of whiskey barrel)
silt = medium (size of pie plate)
clay = smallest (size of penny)

Front 37

how does soil particle type determine permeability

Back 37

larger soil particle = more pore space = greater permeability
smaller soil particle = less pore space = less permeable

Front 38

difference in pore space in saturated v. unsaturated zone

Back 38

saturated zone = pore space full of water
unsaturated zone = pore space has both air and water in it

Front 39

capillary forces in soil

Back 39

describes the attraction of water molecules to soil particles; responsible for moving groundwater from wet areas of the soil to dry areas

Front 40

layers of the unsaturated zone

Back 40

upper part is soil-water zone

Front 41

soil water zone v. infiltration rate

Back 41

has lots of worm and animal burrows and voids left by plant roots which increase infiltration rate

Front 42

fate of soil water in soil-water zone

Back 42

fate - uptaken by plants, transpiration, direct evaporation

Front 43

construction of a well

Back 43

pipe inserted into drilled hole; screen attached at the pipe's base to filter out earth materials

Front 44

how water enters a well

Back 44

below water table, water is under enough pressure to allow water to enter wells

Front 45

relative depth of water table

Back 45

shallower near permanent bodies of water

Front 46

how does the depth of water table vary in any given location?

Back 46

varies seasonally and year to year due to the amount of groundwater recharge (due to changes in quantity, distribution and timing of precipitation)

Front 47

how do we determine the depth of the water table in a location?

Back 47

by installing wells that penetrate the top of the saturated zone far enough to hold standing water

Front 48

uses of a water table map

Back 48

1. estimating the approximate depth of a proposed well
2. to tell the direction of GW flow in given location
ONLY GOOD FOR A SHORT PERIOD OF TIME

Front 49

what is a hydraulic head?

Back 49

a calculation used to describe the potential energy in a ground water flow system; for example, whether there is enough flow to support a small or large well

Front 50

What determines the amount of dissolved chemicals in groundwater?

Back 50

deeper flow paths mean longer contact time with subsurface (underground) materials, so deeper groundwater tends to have more dissolved minerals in it than shallower water

Front 51

what is groundwater flux?

Back 51

the quantity of groundwater discharge to surface water

Front 52

what is a seepage pattern?

Back 52

the way that water seeps or flows from SW to GW or vice versa

Front 53

what affects seepage patterns back and forth between SW and GW?

Back 53

1. permeability of soil
2. changing meteorological (weather) patterns
3. amount of transpiration of plants near the shore of SW
4. amount of GW being pumped near a stream

Front 54

what is focused recharge?

Back 54

it is the greater recharge that occurs when the land has depressions (low spots) in it that make for thin unsaturated zones under them

Front 55

what causes the direction of flow between GW and SW to go back and forth?

Back 55

1. diurnal changes during growing season
a. night = GW --> SW
b. day = SW --> GW v
(plants draw more in as
they transpire)
2. seasonal change (during
winter, plants aren't
drawing water so GW to
SW)

Front 56

focused recharge v. drawdown by transpiration

Back 56

focused recharge greater during wet season
drawdown greater during dry periods due to transpiration

Front 57

what are "edge effects"?

Back 57

at edge of shoreline, the direction of water flow can change rapidly. Affects smaller body of water (more total shoreline area) more than larger body of water (less total shoreline area)

Front 58

3 ways that streams interact with GW

Back 58

1. GW --> SW (gaining stream)
2. SW --> GW (losing stream
3. A combination gaining and losing along the stream's path

Front 59

3 things that cause SW to flow into GW for short periods of time

Back 59

1. extra precipitation
2. storm surges
3. increased transpiration

Front 60

stream stage

Back 60

the height or elevation of the stream's water surface above a reference elevation (like sea level)

Front 61

causes of bank storage

Back 61

extra storm precipitation, rapid snowmelt, release of water from a dam or reservoir upstream

Front 62

what is the effect of drawing too much GW from wells on the contamination of GW?

Back 62

The more GW is withdrawn, the more likely the direction of water flow will change and SW will flow to GW. This means contaminants of SW will move into GW.

Front 63

what is dynamic equilibrium (DE)?

Back 63

a balance in the movement of water in and out of GW

Front 64

what happens to GW when you place well(s) in an aquifer?

Back 64

after continuous pumping, reaches new DE

Front 65

vadose zone

Back 65

unsaturated zone