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Geog 203 Study Guide
water |
the physical reality of life is defined by ______ |
70 |
our own bodies are about ____% of water, as are plants and animals |
water-resource management |
what is the term for rearranging surface water resources to suit our needs by
1. drilling wells
2. building cisterns and reservoirs
3. building dams and diverting streams to redirect water either spatially or temporally |
Africa and Asia |
what two countries make up 93% of the 2.4 billion people lacking adequate sanitary facilities for water.
HINT: One makes up 80% and the other makes up 13%. |
the hydrologic cycle |
involves th circulation and transformation of water throughout Earth's atmosphere, hydrosphere, lithosphere, and biosphere |
surface |
the hydrologic cycle has operated for billions of years, from the lower atmosphere to several kilometers beneath the Earth's _____ |
ocean |
more than 97% of Earth's water is in the _____ |
86 |
what percentage of evaporation is from the OCEAN? |
14 |
what percentage of evaporation is from LAND? |
atmospheric advection of water vapor |
out of the 86% of evaporation, 66% of it combines with 12% of _______ ________ _ ____ ____ from the land to produce 78% of all precipitation that falls back into the ocean |
precipitation |
the remaining 20% of moisture evaporated from the ocean, plus 2% of land-derived moisture, produces the 22% of all ________ that falls over land |
precipitation |
all evaporation is equal to all ________ |
advection |
______ in the atmosphere is balanced by surface and subsurface water runoff |
overland, soil |
Precipitation that reaches Earth's surface follows two basic pathways:
1. flows ______
2. soaks into the _____ |
interception |
occurs when precipitation strikes vegetation or other ground cover |
infiltration |
penetration of the soil surface |
stem flow |
intercepted water that drains across plant leaves and down their sems to the ground is ____ ____ |
throughfall |
precipitation that falls directly to the ground, coupled with drips from vegetation (excluding stem flow) |
percolation |
the downward movement of water through soil and rock due to gravity |
residence |
the ________ time for a water molecule in any part of the hydrologic cycle determines its relative importance in affecting Earth's climates |
short |
the _____ time spent by water in transit through the atmosphere (10 days) plays a role in temporary fluctations in regional weather patterns |
long |
______ residence times, such s 3000-10000 years in deep-ocean circulation, groundwater aquifiers, and glacial ice, act to moderate temperature and climatic changes |
soil-water budget |
measuring the precipitation "supply" input and its distribution to satisfy te "demand" outputs of plants, evaporation, and soil-moisture storage in the area considered |
precipitation |
If you think of a soil-water budget as a money budget:
________ income must be balanced against expenditures for evaporation, transpiration, and runoff |
soil-moisture |
In the soil-water budget, _____-_______ storage acts as a savings account, accepting deposits and withdrawals of water. Sometimes all expenditure demands are met, and any extra water results in a surplus. At other times, precipitation and soil-moisture income are inadequate to meet demands, and a deficit (water shortage) results |
precipitation |
the moisture supply to Earth's surface (rain, sleet, snow, and hail are most common) |
rain guage |
precipitation is measured with what? |
rain guage |
a large measuring cup that collects rainfall and snowfall so the water can be measured by depth, weight, or volume. |
wind |
what may cause the rain guage to have an undercatch as a result of drops or snowflakes not falling vertically |
water balance equation |
PRECIP = (POTET-DEFIC) + SURPL +/- change in STRGE |
potential evapotranspiration |
amount of water that would evaporate and transpire under optimum moisture conditions when there is adequate precipitation and soil moisture supply |
evaporation |
the net movement of free water molecules away from wet surface into air that is less than saturated |
transpiration |
a cooling mechanism in plants when a plant moves water through small openings called stomata in the underside of its leaves. The water evaporates, cooling the plant, much as perspiration cols humans |
14 |
___% of evapotranspiration occurs from land and plants |
evapotranspiration |
evaporation and transpiration combined into one term is called _________ |
potential evapotranspiration |
filling a bowl with water and letting the water evaporate illustrates what concept |
demand |
when a bowl becomes dry, there is still and evaporation _____ |
Southwest |
higher values of POTET occur in the South, with the highest readings in the ________ |
latitudes, elevations |
lower values of POTET are found at higher _______ and _______, which have lower average temperatures |
evaporation pan |
one method of measuring POTET is using an _________ ___, or evaporimeter (not so good measurements) |
lysimeter |
one more elaborate measuring device is an _______ |
POTET |
if you know monthly mean air temperature and daylength, you can approximate _________ _________ (use the abbreviation) |
demand |
the POTET _______ can be satisfied in 3 ways:
1. by PRECIP
2. by moisture stored in the soil
3. through artificial irrigation |
deficit |
if sources are inadequate to meet moisture demands, the location experiences a moisture shortage. This describes what? |
actual evapotranspiration |
POTET-DEFIC = _______ _____________ (ACTET) |
surplus |
if POTET is satisfied and the soil is full of moisture, then additional water input becomes ________ |
total runoff |
the overland flow combines with the precipitation and groundwater flows into river channels to make up the _____ ______ |
soil-moisture storage |
the volume of water stored in the soil that is accessible to plant roots |
soil moisture |
____ ________ comprises two categories of water
1. hygroscopic
2. capillary (only category accessible to plants) |
hygroscopic water |
is inaccessible to plants because it is a molecule-thin layer that is tightly bound to each soil particle by the hydrogen bonding of water molecules |
wilting point |
relative to plants, soil is at the ______ ____ when all that remains is this inaccessible water; plants wilt and eventually die after a prolonged period of such moisture stress |
capillary water |
is generally accessible to plant roots because it is held against the pull of gravity in the soil by hydrogen bonds between water molecules, which cause surface tension, and by hydrogen bonding between water molecules and the soil |
available water |
most capillary water that remains in the soil is ________ ____ in soil-moisture storage |
field capacity |
after some water drains from the larger pore spaces, the amount of available water remaining for plants is termed ______ ________, or storage capacity |
gravitational water |
when soil becomes saturated after a precipitation event, any water surplus in the soil body becomes ________ _______ |
capillary |
it percolates from the shallower ________ zone to the deeper groundwater zone |
greater |
as soil-moisture utilization removes soil water, the plants must exert _____ effort to extract the amount of moisture they need |
irrigation |
avoiding a deficit and reducing plant growth inefficiencies are the goals of _________, for the harder plants must work to get water, the smaller their yield and growth will be |
replenishes |
whether from natural precipitation or artificial irrigation, water infiltrates the soil and _________ available water, the process of sil-moisture recharge |
porosity |
the texture and the structure of the soil dictate ______ |
permeability |
the property of the soil that determines the rateof soil-moisture recharge is its __________ |
saturated |
water infiltration is rapid in the first minutes of precipitation and slows as the upper soil layers become ________, even though the deeper soil is still dry |
drought |
less precipitation and higher temperatures make for drier conditions over an extended period of time |
drought |
scientists and resource managers use four technical definitions for ______
1. meteorological drought
2. agricultural drought
3. hydrological drought
4. socioeconomical drought |
meteorological drought |
defined by the degree of dryness, as compared to a regional average, and the duration of dry conditions |
atmospheric |
the definition of meteorological drought is region-specific, since it relates to __________ conditions that change from area to area |
agricultural drought |
occurs when shortages of precipitation and soil moisture affect crop yields |
slowly |
losses can be significant and are running in the tens of billions of dollars each year in the United States, although agricultural drought evolves _______ and gets little media coverage |
hydrological drought |
relates to the effects of precipitation shortages (both rain and snow) on water supply |
increases |
when streamflow decreases, reservoir levels drop, mountain snowpack declines, and groundwater mining _______ |
socioeconomic drought |
results when reduced water supply causes the demand for goods to exceed the supply, such as when hydroelectric power production declines with reservoir depletion |
uneven |
water distribution is ______ over space and time |
streams |
________ may be perennial or intermittent |
runoff |
the total ______ that moves through them comes from surplus surface water runoff, subsurface throughflow, and groundwater |
equator |
the highest runoff amounts are along the ________ within the tropics, reflecting the continual rainfall along the ITCZ |
Southeast Asia |
___________ _____ also experiences high runoff, as do northwest coastal mountains in the Northern Hemisphere |
seasonal |
in countries having great _______ fluctuations in runoff, groundwater becomes an important reserve water supply |
lower |
regions of _____ runoff coincide with Earth's subtropical deserts, rain-shadow areas, and continental interiors, particularly in Asia |
groundwater |
the largest potential freshwater source in the hydrologic cycle (larger than all surface lakes and streams combined) |
irreversible |
groundwater is generally free of sediment, color, and disease organisms, although polluted groundwater conditions are considered __________ |
70 |
between Earth's land surface and a depth of 4km worldwide, some 8,340,000 cubic km of water resides, a volume comparable to ___ times all the freshwater lakes in the world |
pollution |
_______ threatens groundwater quality, and overconsumption depletes groundwater volume in quantities beyond natural replenishment rates |
independent |
groundwater is not an __________ source of water, for it is tied to surface supplies for recharge |
surplus |
groundwater begins as ______ water, which percolates downward as gravitational water fromt he zone of capillary water |
aeration |
excess surface water moves thorough the zone of ___________, where soil and rock are less than saturated |
subsurface |
__________ rocks are either permeable or impermeable |
saturation |
eventually, water reaches an area where subsurface water accumulates, the zone of __________ |
water |
here the pores are completely filled with _____ |
aquifier |
a rock layer that is permeable to groundwater flow adequate for wells and springs |
aquiclude |
a body of rock that does not conduct ater in usable amounts, also called an aquitard |
water table |
the upper limit of the water that collects in the zone of saturation |
transition |
the water table is the surface where the zone of saturation, a narrow capilary fringe layer, and the zone of aeration are in ________ |
conified |
a ________ aquifer is bounded above and below by impermeable layers of rock or sediment |
unconified |
an _________ aquifer has a permeable layer on top and an impermeable one beneath |
recharge |
conified ad unconified aquifers differ in the size of their ______ area, which is the ground surface where water enters an aquifer to recharge it |
unconified |
for an ________ aquifer, the aquifer recharge area generally extends above the entire aquifer |
conified |
in a ______ aquifer, the recharge area is more restricted |
pressure |
conified and unconified aquifers also differ in their water _______ |
potentiometric |
water in a conified aquifer is under the pressure of its own weight, creating a pressure level to which the water can rise on its own, the ________________ surface |
artesian |
_________ water, or groundwater confined under pressure, may rise in a well and even flow at the surface without pumping if the top of the well is lower thanthe potentiometric surface |
elevation |
groundwater tends to move toward areas of lower pressure and _________ |
water table |
water wells can work only if they penetrate the ______ _______ |
springs |
where the water table intersects the surface, it creates _______ |
bottom |
when the _______ of the stream bed is no longer in contact with the declining water table, streamflow seeps into the aquifer |
drawdown |
as water is pumped from a well, the surrounding water table within an unconfined aquifer my experience ________, or become lowered |
drawdown |
occurs if the pumping rate exceeds the replenishment flow of water into the aquifer or the horizontal flow around the well |
depression |
the lowering of the water table around the well as a result of drawdown is a cone of __________ |
groundwater mining |
the name for aquifers being frequently pumped beyond their flow and recharge capacities |
overdrafts |
in the US today, large tracts experience chronic groundwater ______ in the Midwest, West, lower Mississippi Valley, and Florida and in the intensely farmed Palouse egion of eastern Washington State |
internal |
a possible effect of water removal from an aquifer is that the aquifer, which is a layer of rock or sediment, will lose its _______ support |
dropping |
the Fresno area of California's San Joaquin Valley has experienced a land level _______ of 10m because of a combination of water removal and soil compaction from agricultural activity |
rapidly |
surface water flows ______ and flushes pollution downstream, but slow-moving groundwate, once contaminated, remains polluted virtually forever |
instream |
________ uses are those that use stream water in the channel, without removing it |
nonconsumptive |
___________ uses, sometimes called withdrawal, or offstream use, remove water from teh supply, use it, and then return it to the same supply |
consumptive |
__________ uses remove water from a stream, but do not return it, so it is not available for a second or third use |
desalination |
an alternative to further groundwater mining and saltwater intrusion under Saudi Arabia |
declines |
water availability per person _______ as population increases, and individual deman increases with economic development, affluence, and technology |
desalination |
involves the removal of organics, debris, and salinity from seawater through distillation or reverse osmosis |