Term
Approximately 71% Of
Earth’s Surface Area Is
Covered By |
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Definition
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Term
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Definition
The cyclical movement of water through
the various reservoirs is represented by the
hydrologic cycle |
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Term
Water is transferred from one reservoir to
another through these processes |
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Definition
– Evaporation
– Precipitation
– Ground infiltration
– Surface runoff
– Transpiration |
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Term
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Definition
| 86% from ocean + 14% from land = 100% |
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Term
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Definition
| 78% over ocean + 22% over land = 100% |
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Term
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Definition
| 14% evapotranspiration + 8% runoff/groundwater = 22% total ppt |
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Term
| 78% ppt over ocean + 8% runoff/groundwater = 86% returned to ocean |
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Definition
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Term
22% of all precipitation on Earth
falls over |
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Definition
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Term
22% of all precipitation on Earth
falls over land: |
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Definition
– Over half is returned to the
atmosphere via evapotranspiration
– The remainder flows to the sea as
runoff |
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Term
| Why so high?(perciptation in NW) |
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Definition
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Term
| Why high? (percipitation in SE) |
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Definition
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Term
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Definition
Evapotranspiration is the combination of
evaporation and transpiration: |
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Term
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Definition
Net movement of water
molecules away from a wet surface into air
that is less saturated |
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Term
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Definition
Outward movement
of water through small openings (stomata) in
the underside of leaves |
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Term
| Over Half Of All Precipitation On Land Is Returned |
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Definition
| To The Atmosphere Via Evapotranspiration |
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Term
| Evapotranspiration over land accounts for |
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Definition
14% of the entire
hydrologic cycle |
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Term
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Definition
Precipitation over land that is not returned
to the atmosphere via evapotranspiration
flows back to the sea as runoff |
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Term
Runoff follows two basic pathways to the
sea: |
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Definition
Overland flow (95%)
– Subsurface flow as groundwater (5%) |
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Term
| 95% Of All Runoff Occurs As |
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Definition
Overland Flow And
Runoff To Streams |
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Term
| 5% Of All Runoff Percolates Through |
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Definition
Underlying
Soil And Bedrock To The Groundwater System |
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Term
| The Water-Balance Equation |
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Definition
The water budget is a portrait of the hydrologic
cycle at a specific site or area |
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Term
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Definition
| – Precipitation at a site is measured using rain gauge |
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Term
| Precipitation input must be balanced |
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Definition
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Term
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Definition
– Actual Evapotranspiration (ACET) is the net outward
movement of water molecules away from land and plants
– Potential Evapotranspiration (POTET) is the water that
would evaporate and transpire under optimum moisture
conditions (when enough moisture is available) |
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Term
| WATER balance equation: precipitation = |
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Definition
| actual evapotranspiration (i.e potential evapotranspiration-deficit) + surplus +- Change in soil moisture storage |
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Term
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Definition
POTET can also be measured with a lysimeter,
which employs a buried tank opened at the
surface |
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Term
Potential evaporation is easily measured using an
evaporation pan: |
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Definition
– As evaporation occurs, water in measured amounts is
replaced in the pan so that no shortage occurs |
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Term
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Definition
there is not enough
precipitation or moisture to meet demand |
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Term
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Definition
there is an oversupply of
water |
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Term
A Weighing Lysimeter For Measuring Evaporation And
Transpiration |
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Definition
Precipitation falls
on lysimeter
Various pathways
of water are traced
Weight of water
added or lost is
measured by scale
Some water
remains as soil
moisture; some is
incorporated into
plant tissues
Water passing
through soil drains
from the bottom of
the lysimeter as
groundwater and
collected in tank
Runoff is collected
in tank and
measured |
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Term
| Water not collected or retained is credited to |
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Definition
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Term
Potential Evapotranspiration (Water Demand)
Factors
include |
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Definition
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Term
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Definition
| Excess water can be temporarily stored as soilmoisture: |
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Term
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Definition
thin molecular layer of water
tightly bound to soil particles but not available for
moisture demands |
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Term
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Definition
held in soil by surface tension and
hydrogen bonding and is generally accessible to
plant roots |
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Term
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Definition
excess water that percolates
downward from the shallower capillary zone to the
deeper groundwater zone |
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Term
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Definition
is water that remains for plants after
water drains from larger pore spaces in soils |
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Term
| Soil moisture from dryest to most wet |
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Definition
| hydroscopic, capillary,gravitational |
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Term
| Best soil for plants is in between |
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Definition
| field capacity and wilting point |
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Term
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Definition
| Moisture supply available |
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Term
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Definition
Amount of water that
would evaporate and transpire under
optimum moisture conditions |
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Term
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Definition
| Actual evapotranspiration |
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Term
If precipitation exceeds the amount
of water required for POTET, |
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Definition
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Term
| If ACTET is less than POTET, |
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Definition
| then a water deficit will occur |
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Term
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Definition
Not enough water available to meet demand
Recent droughts around the world (e.g. Australia
and southwestern US) possibly linked to global
climate change |
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Term
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Definition
Meteorological drought:
Agricultural drought:
Hydrologic drought
Socioeconomic drought |
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Term
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Definition
Lower precipitation, higher
temperatures and reduction in soil moisture |
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Term
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Definition
Changes in soil moisture and
weather as they affect crop yields |
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Term
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Definition
Reservoir levels drop, stream flow
decreases and groundwater mining increases |
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Term
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Definition
Water rationing, wildfires, and
other problems affecting the economy and society |
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Term
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Definition
| Groundwater Profile and Movement |
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Term
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Definition
Groundwater is water found in the pores of soil
and sediment, plus narrow fractures in bedrock |
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Term
About 50% of U.S. population derives a
portion of its freshwater from |
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Definition
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Term
| Groundwater supplies up to |
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Definition
100% of
freshwater in some rural areas |
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Term
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Definition
| pore spaces filled with water +air |
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Term
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Definition
| is under the water table. pore spaces filled with 100% water |
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Term
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Definition
upper
surface of
the saturated
zone |
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Term
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Definition
~4 km of the
Earth’s surface |
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Term
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Definition
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Term
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Definition
Porosity is the percentage of open spaces
within a given volume of regolith or rock |
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Term
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Definition
Permeability is a measure of how easily a
rock allows fluids to pass through it |
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Term
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Definition
porosity: very high
permeability: very high |
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Term
| coarse to medium grained sand |
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Definition
porosity: high
permeability: high |
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Term
| fine grained sand and salt |
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Definition
porosity: moderate
permeability: moderate to low |
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Term
| sandstone, moderately cemented |
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Definition
porosity: moderate to low
permeability: low |
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Term
| fractured shale or metamorphic rocks |
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Definition
porosity: low
permeability: very low |
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Term
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Definition
porosity: very low
permeability: very low |
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Term
Characteristics of Groundwater
Table |
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Definition
– Intersects the land surface at lakes, marshes,
springs, and streams
– Somewhat imitates the overlying land surface
– May drop during dry seasons
– Rises after heavy rainfalls |
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Term
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Definition
| the water table falls, reducing stream flow and drying up some wells |
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Term
| Recharge of groundwater occurs in |
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Definition
areas
where precipitation seeps downward to
the saturation zone:
Groundwater then flows to discharge
areas |
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Term
In areas of abundant rainfall, the recharge
area may encompass the |
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Definition
entire landscape
beyond stream channels |
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Term
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Definition
recharge occurs beneath an
influent stream |
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Term
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Definition
Stream is site of
groundwater discharge |
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Term
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Definition
Stream is site of
groundwater recharge |
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Term
The time water takes to move through the
ground from recharge to discharge
depends on: |
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Definition
– Permeability of material
– Travel distance
– Path of flow
Can range from days to thousands of years |
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Term
| A Well Supplies Water When It |
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Definition
Penetrates the Water
Table and Enters the Zone of Saturation |
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Term
| A Cone Of Depression Forms When |
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Definition
The Rate Of Water Withdrawal
Exceeds The Rate Of Local Groundwater Flow |
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Term
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Definition
is a body of rock such as shale
that does not conduct water in usable amounts |
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Term
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Definition
is a highly permeable rock such as
sandstone or porous limestone within the zone
of saturation |
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Term
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Definition
Unconfined (not bound by aquicludes)
– Confined (bounded above and below by aquicludes |
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Term
| Hydrostatic Pressure Is The |
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Definition
Weight That An Overlying
Column Of Water Would Exert At A Particular Depth |
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Term
| Water under hydrostatic pressure seeks |
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Definition
to rise to the same
height as its pressure (potentiometric) surface |
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Term
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Definition
Artesian system occurs where
groundwater under pressure rises above
the level of an aquifer |
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Term
| Two conditions are necessary: |
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Definition
– Aquifer is inclined with one end receiving
water (recharge area)
– Aquifer is confined with aquicludes above
and below |
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Term
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Definition
In artesian wells, water rises on its own
without pumping |
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Term
| Two types of artesian wells |
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Definition
Nonflowing occurs when pressure surface is
below ground and water does not reach
surface
– Pressure surface above ground creates a
flowing artesian well |
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Term
Changes in the Water Table
With Time |
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Definition
In regions where withdrawal of water
exceeds recharge, the water table will
gradually drop |
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Term
High
Plains
Aquifer
170,000 wells
irrigate |
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Definition
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Term
Groundwater can be
contaminated by: |
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Definition
– Drainage from septic
tanks, broken sewers
and barnyards
– Agricultural poisons
– Highway salts
– Buried hazardous
wastes
– Invading seawater
along coastal areas |
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Term
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Definition
Water supply in the United States comes
from surface and groundwater sources |
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Term
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Definition
BGD: Billions
of gallons a day
Of the average
4200 BGD
precipitation
received by the
U.S., 71% ends up
as ACTET while
29% is surplus |
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Term
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Definition
of
vegetation; all
water as ACTET is
returned to the
atmosphere |
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Term
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Definition
runoff available for
withdrawal,
consumption, and
various instream
(navigation,
wildlife,
hydroelectric
power, etc.) uses |
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Term
Surplus water that
is not consumed
eventually ends up |
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Definition
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Term
All the
precipitation
received is
eventually returned |
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Definition
to the atmosphere
and ocean |
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Term
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Definition
Desalination of seawater can
augment diminishing
groundwater supplies |
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Term
| For the following illustration of the Hydrologic Cycle, what do the yellow arrows represent? |
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Definition
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Term
| Most runoff on land occurs in the subsurface as groundwater. |
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Definition
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Term
| What percentage of water evaporated over land and water eventually ends up as precipitation? |
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Definition
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Term
| What is potential evapotranspiration? |
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Definition
| Amount of water that would evaporate and transpire under optimum (saturated) moisture conditions |
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Term
| In the water balance equation, actual evapotranspiration (ACTET) is equal to... |
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Definition
| Potential evapotranspiration (POTET) minus deficit (DEFIC) |
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Term
| or the following figure of the water budget for Saskatoon, Saskatchewan, the blue curve represents precipitation, the orange curve potential evapotranspiration (POTET), and the green curve actual evapotranspiration (ACTET). During what time of year is the moisture deficit the greatest? |
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Definition
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Term
| With regard to soil-moisture storage, what happens to excess moisture (known as gravitational water) that cannot be held in the soil? |
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Definition
| Excess moisture percolates downward to the deeper groundwater zone |
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Term
| Which of the following statements about groundwater is FALSE? |
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Definition
| Groundwater only consists of subsurface water that occurs above the water table |
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Term
| Which of the following statements about groundwater is TRUE? |
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Definition
| Groundwater flows from areas of recharge to discharge |
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Term
| __________ is a measure of how readily groundwater flows through soil, sediment, and bedrock |
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Definition
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Term
| Which of the following has the highest porosity and would therefore make the best aquifer? |
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Definition
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Term
| In order for an aquifer to be an artesian system and supply well-water to the surface without pumping, the aquifer must be _________ and ______________. |
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Definition
| Inclined/bounded above and below by aquicludes |
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Term
| If groundwater was excessively pumped by wells over a long period of time, which of the following would most likely result? |
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Definition
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