67 terms

Water Resources

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What percent of the Earth is freshwater?
3%
Of the 3% of the Earth's freshwater, how much is surface water and available for human use?
.03%
What problem with water is there as the population grows?
uneven distribution of water
When it precipitates, water will either...
1. run off to become surface water
2. infiltrate into the ground and become groundwater
3. evapotranspirate
What is the difference between a confined and an unconfined aquifer?
An unconfined aquifer has a surface pressure equal to that of the atmosphere and will fill up with water when it rains.
A confined aquifer is trapped by layers of impermeable rock that can build up additional pressure to the point where it can exceed ground elevation pressure and pump water like a spring.
Where does the confined aquifer receive its water from?
The recharge area
What is the water table?
The boundary between the saturated zone and the unsaturated zone.
Does the water table move up and down?
Yes depending on how much water was withdrawn or put into the ground.
What are our 3 problems with water usage?
1. We currently use more than 1/2 of the world's reliable runoff of surface water
2. About 70% of the water we withdraw from rivers, lakes, and aquifers is not returned to these sources (which ultimately depletes water from this original area)
3. Irrigation is the biggest user of water (then industries and cities/residences)
What are the 2 types of aquatic biomes?
Saltwater and Freshwater
What are the 2 types of freshwater?
Flowing (Iiotic) and Standing (stentic)
What is an ecosystem service?
It is something that we get from the ecosystem that is valuable.
What are the 2 types of ecosystem services?
Economic and Ecological services
What are the 7 ecological services in freshwater systems?
1. climate moderation
2. nutrient cycling by animals
3. waste treatment
4.flood control
5. groundwater recharge
6. habitats for species
7. genetic resources and biodiversity
What are the 7 economic services in freshwater systems?
1. food
2. drinking water
3. irrigation water
4. hydroelectricity
5. transportation corridors
6. recreation
7. employment
Lakes are classified according to their...
nutrient content and primary productivity
What are the 2 types of lakes?
Oligotrophic and Eutrophic
What are the characteristics of an oligotrophic lake?
newly formed
poorly nourished
little sediment
deep waters
clear waters
low net primary prod
has trout, bass, etc
What are the characteristics of a eutrophic lake?
excess supply of nutrients
shallow
murky
high net primary prod
lots of plants and fish
True or False: All lakes eventually become eutrophic.
True, but humans quicken the process (cultural eutrophication)
True or False: Plant nutrients cannot affect the type of organisms and numbers it can support.
False
What is eutrophication?
an increase in the rate of supply of organic matter in an ecosystem that can deplete the oxygen supply (natural = excess plant nutrients; cultural = quickening of the natural process by human activities such as little in sewage)
What is a watershed/drainage basin?
the region draining into a river, river system, or other body of water
What direction do rivers and streams in?
downhill
What are the 3 zones of down-hill flow?
1. source zone - narrow headwaters with cold, rapid, clear waters and a high DO
2. transition zone - wider, deeper, slower, and warmer waters with a low DO
3. floodplain zone - stream joins into muddy river waters with a lower DO
What is DO?
Dissolved Oxygen
What is the relationship between DO and water temperature?
There is a higher concentration of DO in colder temperatures.
What is the natural pH of water? Why?
6.5 because of carbon dioxide that dissolves well in water
What forms carbonic acid?
water and carbon dioxide
True or False: Gas solubles in liquids increase with an increase in temperature.
False; it decreases with an increase in temperature
What is the biggest use of freshwater?
Agriculture (irrigation)
What are the advantages of withdrawing groundwater?
useful for drinking and irrigation
found everywhere
available year-round
renewable unless overpumped or contaminated
no evaporation losses
cheaper to extract
What are the disadvantages to withdrawing groundwater?
aquifer depletion from overpumping
sinking of land (subsidence) from overpumping
polluted aquifers can last for centuries
there could be saltwater infusion from overpumping
reduced water flows into surface waters
What is the result of depleted aquifers?
dry streams and lakes because a lot of our groundwater supplies water for them (if an unconfined aquifer reaches the surface, it forms into a lake)
What is Ogallala?
the largest aquifer in the world
Where are areas of greatest aquifer depletion from groundwater in the US?
GA, FL, and many western states
What is saltwater intrusion?
When an area of underground water mixes with saltwater when the groundwater gets overpumped, causing the water to move further away and the seawater to move closer in. The seawater will soon then come so close that it will inflitrate the water in a well.
What is a sinkhole?
Depressions in the ground that form when the roof of an underground cavern collapses after being drained of groundwater. They usually only form in very porous limestone that allows water to be held, so when the water is overpumped or it dissolves the limestone, there will be no more hydrostatic pressure and the limestone will collapse.
Leaking water pipes can also lead to sinkholes because it washes away durable rocks that hold up the water.
What are ways to prevent groundwater depletion?
waste less water
subsidize water conservation
ban the use of wells near surface water
ban and retire groundwater withdrawal rights
do not grow water intensive crops
What are ways to control groundwater depletion?
raise price of water
tax water pumped from wells
set and enforce min. stream flow levels
What are 5 ways to increase water supply and which is the best way?
1. build more dams and reservoirs
2. transport water in from other areas
3. desalinate
4. reduce water use/increase water efficiency (BEST WAY)
5. import food to help reduce the use of local irrigation water for farming
What are the advantages and disadvantages of using dams and reservoirs?
Advantages:
-stores water for human use
-recreation
Disadvantages:
-slows downstream flow
-disrupts reproductive cycle of many fish
-hold back sediment that need to go downstream to replenish marsh areas that will sink if otherwise and fertilize some areas
-reservoirs have a large surface area which means faster evaporation rates
True or False: Transferring water from one plant to another can make an unproductive area more productive but can cause environmental harm.
True; it encourages unsustainable use of water in areas water is not naturally supplied.
What is the biggest waste of water?
Water loss due to evaporation and leaks
What is desalination?
the removal of salt (especially from sea water) to make it suitable for drinking
What are the 2 ways to desalinate?
1. distillation
2. reverse osmosis
Why is desalination not the primary method for more water?
It is very expensive and there is the issue with waste water. You can't dump it into the ocean,refine it into salt, or contaminate the groundwater with it. (There are plants but that costs a lot of energy and money)
Desalination is only a good solution for those countries that...
are wealthy island nations
What are ways to reduce water usage/increase water efficiency?
use recycled water (grey water)
fix leaky pipes
replace things with water saving things
xeriscaping
What are the 3 irrigation techniques?
1. gravity flow (water flowing downhill)
2. drip irrigation (water being delivered to individual plant roots by tubes)
3. central pivot (water pumped from mobile sprinklers)
How have humans contributed to local flooding?
removing areas that absorb water
rapid population growth
deforestation
overgrazing
unsustainable farming on steep hills
cleaning coastal mangrove forest
Difference between consumptive use of water and nonconsumptive?
Consumptive - use of water that is not returned to its original area
Nonconsumptive - use of water that is not removed or only temporarily removed
In the east of the US, what is most water used for?
energy production, cooling , manufacturing
What are the serious problems with water usage in the east?
flooding, urban shortages, pollution
What are the uses for water in the west? Problems?
irrigation (droughts and evaporation)
What are water hot spots and where are they?
They are areas in the US where there is competition for scarce water (mostly in the west)
True or False: A lot of the world's population live in river basins that do not have enough freshwater.
True
What are main factors causing water scarcity?
dry climate and droughts
True or False: Farmers are losing access to water against cities.
True
True or False: Aquifer depletion is invisible until it is too overpumped or depleted.
True
What has accelerated overpumping?
Widespread drilling of inexpensive tubewells
What is reverse osmosis also called?
Microfiltration
What is the main cause of water waste besides evaporation and leaky pipes?
We pay too little for it
How can we mimic the way nature deals with waste and save water?
Use the sludge from sewage treatment plants as fertilizers.
What naturally causes flooding?
Heavy rainfall, rapid snowmelt, removal of vegetation and destruction of wetlands
True or False: A lot of people live in floodplains.
True.
What can reduce flooding?
straightening and deepening streams (channelization but it limits habitats)
levees or floodwalls (but damages downstream)
dams