~Water- essential for all living processes: dissolves nutrients
and distributes them to cells, regulates body temperature, supports
structures, and removes waste products; 60% of our body is water
and 70% of the world's surface is covered in it.
~The hydrologic cycle- the circulation of water as it evaporates
from land, water, and organisms, enters the atmosphere, condenses
and precipitates to the earth's surfaces, and moves underground
by infiltration or overland by runoff into rivers lakes and seas:
Allows for a fresh supply of water, maintains a habitable climate
and moderates world temperatures. Plants help add water vapor
to the air through transpiration.
Evaporation= process through which liquid is turned into a gas
way below its boiling point
*Sublimation= when water moves from the solid to the gaseous form
with out ever being liquid (occurs on bright, dry cold winter
days)
*Saturation point= when a volume of air contains the most water
vapor that it can at a given temperature
*Relative humidity= the amount of water vapor in the air expressed
as a percentage in terms of the saturation point
*Condensation= when saturation point is exceeded and water molecules
begin to aggregate
*Dew point= the temperature at which condensation occurs
*Condensation nuclei= tiny particles that help facilitate the
condensation process (smoke, dust, sea salts, spores, etc)
*Cloud= accumulation of condensed water vapor in droplets or ice
crystals
~Mountains have two different climates: the windward side is cool
wet and cloudy; the leeward side is warm dry and sunny, ex. Himalayans
(dry spot on mtn= rain shadow)
~Deserts lack moisture and have much evaporation due to the descending
air masses. The air will condense under the higher pressure and
warms through adiabatic heating. This typically occurs at 30 degree
latitudes North and South of the equator. Typical deserts include
the Sahara, Gobi, and Death Valley.
~Tropical rainforests receive much rain
~Oceans make up 86% of evaporation, 90% returns directly to the
ocean: the other ten percent is carried onto the continents- once
there some is incorporated into plants and animals, the rest seeps
into the underground but all eventually returns to the ocean.
40,000 km2 of surface runoff and underground flow represents the
renewable supply for us and freshwater-deep ecosystems.
~Evaporation and condensation help regulate the climate, as winds
redistribute the heat and moisture
~Oceans= contain 90% of all bio mass and 97% of all the liquid
in the world. They moderate the global temperature- warm water
flow from tropics to poles and vice versa,
*Residence time= that length of time an individual molecule spends
circulating in the ocean before evaporation, on average its 3,000
years
~Glaciers hold almost 90% of the earths freshwater. These frozen
rivers slowly move downhill. Antarctic glaciers contain 85 % of
all the ice in the world.
GROUNDWATER:
-Second largest freshwater reservoir
~Ground water= holds next largest amount of fresh water
*Infiltration= precipitation that doesn't evaporate and runs
through fractures of the rocks in the soil
*Zone of aeration= upper soil layers that hold both air and water,
moisture for plant growth comes from here. The depth varies.
*Zone of saturation= lower levels where all soil air spaces are
filled with water. The top of the zone is called the water table
and it is neither flat nor stationary. Aquifers: porous layers
of sand etc. below water table
-Artesian well: water gushes out without being pumped
YES!
*Storage reservoirs drown free-flowing rivers
*They can submerge towns, farms, and cemeteries and important historic
sites
*Block fish migration- salmon migration routes impeded
*Can change aquatic habitats that were important to species
*Siltation of reservoir behind dam builds up requiring dredging.
*Nutrients carried within the silt and clay are lost to down stream
farmlands that would normally be deposited during floods.
*Dam breakage could devastate communities living downstream.
NO!
*Stores water, and generates electricity
*Create jobs for workers
*Help economic development
*Allows arid and unfarmable lands to grow crops through irrigation
of water
Main problem with dams are their inefficiency!!! Dams lose
water through evaporation, and seepage through porous rocks~~~>
wasting more water than they make available.
* Accumulating sediments can clog reservoirs and make dams completely
useless~~~> lose a lot of valuable nutrients. Silts can be
replaced with commercial fertilizers costing more than 100 million
bucks a year!
LOSS OF FREE-FLOWING RIVERS
Hetch Hetchy Valley in Yosemite National Park: San Francisco wanted
to dam the Tuolumne River in the park to produce hydroelectric
power and provide water for the city. Some people liked it because
it supported clean water and power. John Muir opposed the dam
project (He founded the Sierra Club and Yosemite Park!! Wahoo!)
He said that Hetch Hetchy valley's beauty should be protected.
The people fought a hard fight but the dam builders won.
WATER MANAGEMENT AND CONSERVATION
*Goal: prevent flood damage and store water for future use instead
of building dams and reservoirs.
Watershed-> also known as a "catchment" is all the
land drained by a stream or river. Retaining vegetation and ground
cover in watersheds help hold back rainwater and decrease downstream
floods.
*More environmentally sound farming and forestry techniques can
help reduce runoff.
*Retaining crop residue on fields can reduce flooding
*Minimizing plowing and forest cutting on steep slopes protect
watersheds
*Conserving wetlands helps preserve natural water storage capacities
and aquifer recharge zones.
Small dams can be just as useful as big dams:
Small dams on tributary streams have the ability to hold back
water before it turns into a big flood. These dams can form ponds,
and they provide useful wildlife habitats! Small dams can be built
with simple equipment and local labor.
***More than 60 million people in 33 states obtain their drinking
water from national forest lands***
DOMESTIC CONSERVATION
How can we help stop water shortages?
Take shorter showers!! Stop leaks!! Efficiently wash your cars,
dishes, and clothes!!! What about appliances? Use low-volume showerheads,
and efficient dishwashers and washing machines!! **If you plant
native ground cover in a "natural lawn" or make a rock
garden, landscape in harmony with the surrounding environment-
xeriscaping (choosing plants that require little moisture) can
be great instead of constantly watering and feeding a dry, arid
garden.***
:0) Our biggest domestic water use is toilet flushing!! eeeew.
We use about 13,000 gallons of drinking quality water annually
to flush toilets. People are now creating low-volume and waterless
toilets.
RECYCLING AND WATER CONSERVATION
*In 3rd world countries 70% of all the agricultural water used
is lost to leaks in irrigation canals, application to areas where
plants don't grow, runoff, and evaporation. People have been trying
to turn to new farming techniques such as leaving crop residue
on fields and ground cover on drainage ways, using mulches, and
low-volume irrigation in order to reduce water losses. And its
been working!
*Cooling electric power plants = bad water usage
*Installing dry cooling systems= better water usage
PRICE MECHANISMS AND WATER POLICY
In the past, water policies were been against conservation. Some
parts of the US were based on riparian use rights= people who
lived near a river could use as much as they wanted as long as
they didn't taint its quality or the limit others who wanted to
access to the water down stream. In many places, like NYC, water
used to be very cheap. People didn't have any incentive to repair
leaks, or restrict usage. The drought of 1988 changed all of these
practices...
*The US is currently saving 38 million gallons a day compared
to per capita rates 20 yrs ago. However, we have 10% less water
because of the growing population!
*Drip irrigation= AWESOME! It applies water directly to plant
roots, but its very expensive. Used on only 1% of farmland worldwide.
*Charging higher proportion of costs to users of public water
projects~~~> encourages conservation!