Water Resources Flashcards
properties of water
dipole, dissolves most polar molecules
characteristics of the water supply in the US
inexpensive, accessible, plentiful, relatively safe to drink
water covers ____% of the earth’s surface
71%
how many cubic kilometers of water exist on earth?
1.3 billion
how much of the water on earth is suitable for consumption?
3%
how much of earth’s water is in the oceans?
97%
how long can humans live without water?
3 days
how many people lack access to clean drinking water?
1.7 billion
how much water do we consume in a day?
3000 liters
how much is the global demand for water increasing annually?
- 2.3 %
- doubling every 21 years
how many people lack access to water for sanitation and waste disposal?
2.5 billion
benefits of water management
- improves water efficiency
- decreases consumption
- preserves remaining resources
three major water consumers in the world
agriculture, industry, households/individuals
US average daily per capita water use
180 gallons
how much of water used for irrigation is lost to evaporation or runoff?
60%
what is the largest use of freshwater?
agriculture, about 2/3
how is water used in industry?
manufacturing, cooling, condensation by power plants, and waste disposal
how much water is used daily by industry in the US?
more than 200 billion gallons
what is the worldwide volume of groundwater?
8.5 million cubic kilometers
groundwater sources supply drinking water to ___% of people in the US
50%
what is an artesian aquifer?
confined on both sides by solid rock, but has an access point through which it can be recharged with groundwater
dug/bored wells
not very deep, wide diameter, pump is at the surface
drilled wells
submersible pump, intake screen, and connection to power source
sources of groundwater contamination
septic systems, underground storage tanks, pesticides, fertilizers, landfills
recharge
replacement of groundwater by natural processes
water stress
ratio of water withdrawal to water availability
ogallala aquifer
- one of the worlds largest aquifers
- beneath the great plains
- under lots of water stress
benefits of wetlands
stabilizes soil and slows surface runoff, allowing more aquifer infiltration
water in the atmosphere
- smallest reservoir, less than 1%
- most rapid turnover rate
increasing water supplies
- building dams, canals, and reservoirs
- seeding clouds
- desalination
types of desalination
distillation and reverse osmosis
how many deaths per year from water borne infectious agents?
25 million
main source of waterborne pathogens
improperly treated human waste
biological oxygen demand
the need for oxygen in an environment
oxygen sag
when the oxygen levels fall below biological oxygen demand
inorganic pollutants
metals, nonmetallic salts, acids and bases
organic pollutants
peticides, herbicides, fungicides, pharmaceuticals, pigments
Safe Water Drinking Act (1974)
- EPA set maximum contaminant levels for water pollutants
- enforcement carried out by the states
oxygen solubility in water ______________ as temperatures increase
decreases
___% of the world’s wastewater flows back into the environment without being treated or reused
80%
types of sewage treatment
pit privies, septic systems, municipal sewage treatment
how deep is the pit in a pit privy?
5-6 feets
in a pit privy, the waste should be frequently covered with _______
lime
the pit of a pit privy must be how far from a water source?
15 meters
how far must a septic tank be from water sources?
15 meters
how far much a leach field be from water sources?
30 meters
primary treatment
physical separation of large solids from the waste stream
secondary treatment
biological degradation of dissolved organic compounds
tertiary treatment
removal of plant nutrients from secondary effluent
what does a comminuter do?
grinds up large materials
what happens in a grit chamber?
rocks, gravel, and dense objects are separated out via rapid sedementation
what happens in the primary clarifier?
sewage settles and separates into sludge on the bottom
what is activated sludge?
biological oxidation process that mixes oxygen and microbes to rapidly break down organic matter, thereby further reducing biological oxygen demand
what happens in the secondary clarifier?
the liquid portion of the material from the activated sludge tank is allowed to settle, most bacteria are removed in this process
disinfection in municipal waste treatment
chlorine and UV radiation
