XIII - Water Flashcards
Freshwater makes up about what percentage of all water?
2.6%
Freshwater composition
- 984% Ice caps & glaciers
- 592% Groundwater
- 014% Readily accessible freshwater
Readily accessible freshwater breakdown
- 007% lakes
- 005% soil moisture
- 001% atmospheric water vapor
- 0001% rivers
- 0001% biota
What percentage of Earth’s water is readily accessible freshwater?
0.003%
What percent of freshwater is used for agriculture?
69%
(60%–80% wasted)
800 gallons = 1 lb
grain–beef
What percent of freshwater is used for industry?
23%
100,000 gallons = 1 car
1,000 gallons = 1 lb of
aluminum
What percent of freshwater is used for domestic purposes?
8%
surface hydrology
Local precipitation leads to surface runoff, ground infiltration, & evapotranspiration (evaporation + transpiration).
Surface water
precipitation that does not infiltrate
the ground or evaporate
Watershed
region from which water drains into a
water body
Groundwater
water that infiltrates the ground & is
stored in voids between soil particles
aquifers
porous, water–saturated layers of soil or
rock through which groundwater flows
recharge area
any area of land through which water
passes into an aquifer
Unconfined aquifers
have a zone of infiltration
above (unsaturated) & a water table below which
is saturated.
Confined aquifers
bounded above & below by
less permeable rock; groundwater in this type of
aquifer is confined under pressure
Groundwater moves from
the recharge area
through an aquifer & out to a discharge area (well,
spring, lake, geyser, stream, or ocean)
Causes of water shortages
Dry climate
Drought
Desiccation
Water stress
Drought
a period in which precipitation is lower &
evaporation is higher than normal
Desiccation
drying of the soil as a result of deforestation
& overgrazing
Processes involved in groundwater hydrology
Evaporation Runoff Precipitation Transpiration Infiltration
Components involved in groundwater hydrology
Confined aquifer recharge area Unconfined aquifer recharge area Confined aquifer Unconfined aquifer Flowing artesian well Stream Lake
Pros of dams & reservoirs
Useful for recreation & fishing
Produce cheap hydro power
Provide year-round irrigation of cropland
Downstream flooding is reduced
Cons of dams & reservoirs
Enormous losses of water through evaporation
Expensive to construct
Disrupted fish migration
Downstream cropland deprived of nutrient rich soil
Danger of collapse
Mass of water can cause earthquakes
flooded land destroys forests/ croplands & displace people
Ways to supply more water
Dams & reservoirs Water transfer Groundwater supplies Desalination Reverse Osmosis
Dams & reservoirs example
Colorado River
Colorado River
system of dams & canals provides electricity & cheap
water for agriculture, industry, & cities
Why doesn’t the Colorado River make it to the Gulf of California?
• limited water supply must be divided between farmers,
ranchers, cities, Native Americans, Mexico, & wildlife
Colorado River conflict
population growth in the lower basin is increasing
demand beyond the allocated supply
California Water Project Problem
• most of the rainfall is in northern California
• most of the population growth & agriculture is in
southern California
California Water Project solution
• water transferred to the south via dams, pumps, &
aqueducts
California Water Project controversy
• southern California wants more water for growing cities
• much of the water transferred is wasted by inefficient
irrigation
• the north needs the water for fisheries & flushing
pollutants out of San Francisco Bay
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Groundwater supplies problems
Groundwater in the U.S. is being withdrawn at about
four times its replacement rate
Consequences of this problem
• aquifer depletion • aquifer subsidence land sinks when water is withdrawn • saltwater intrusion
Using water efficiently
Increase efficiency of irrigation Use recycled water Fix leaky pipes Water-saving toilets, faucets, & shower heads Xeriscaping
How to increase efficiency of irrigation
drip irrigation, central–pivot, computer monitoring
How to use recycled water
treat gray water from showers, washing machines for
reuse
Xeriscaping
plant drought–tolerant vegetation in residential
communities located in arid & semi–arid areas
Desalinization
Making fresh water
from salt water
How does desalinization work
Boiling salt water-> steam -> collect steam
Reverse osmosis
Making freshwater from salt water using hydrostatic and osmotic pressure
Flooding
result of heavy, prolonged rain or rapid snowmelt causing water in a river to
overflow its channel
How can human activities exacerbate flooding?
either increasing the probability of a flood or
increasing the severity of a flood
Human activities that
exacerbate flooding
• Removing vegetation, logging, overgrazing,
forest fires, mining, urbanization
• Destruction of wetlands
• Building in floodplains & replacing vegetation
with concrete
How can destroying wetlands contribute to excess flooding?
wetlands absorb surface runoff & release it
slowly to the river
How can replacing vegetation with concrete contribute to excess flooding?
loss of vegetation causes rapid runoff of
rainwater
