Upload
roderick-james
View
227
Download
0
Tags:
Embed Size (px)
Citation preview
Water Resources
“It is not until the well runs dry, that we know the worth of water.”
Benjamin Franklin
Properties of Water Strong hydrogen bonds Remains liquid over wide temp range High heat capacity
Protect living things from temp fluctuations Moderates climate Excellent coolant
Properties of Water video Water-Liquid Awesome, Crash Course
Properties of Water con’t Need a lot heat to evaporate water Excellent solvent Water molecules can ionize into H+ and OH- to
help maintain balance between acids and bases in the cells
Filters out UV radiation from aquatic organisms Capillary action Expands when it freezes/ice has lower density
Fresh Water? 97% too salty Most of 3%
freshwater is locked up in ice caps or too deep to be used
.024% easily available
Unconfined & Confined Aquifer
Groundwater System Surface runoff Watershed or drainage basin Groundwater Zone of Saturation Water table Zone of aeration Aquifer Recharge area
Groundwater System
Slide 3Slide 3Slide 3Slide 3Slide 3Slide 3Slide 3Slide 3Slide 3Slide 3Slide 3Slide 3Slide 3
Evaporation and transpiration
Evaporation
Stream
Infiltration
Water tableInfiltration
Unconfined aquifer
Confined aquifer
Lake
Well requiring a pump
Flowingartesian well
Runoff
Precipitation
ConfinedRecharge Area
Aquifer
Less permeable materialsuch as clay
Confining permeable rock layer
Unconfined Aquifer Recharge Area
Figure 14-3Page 315
Uses of World’s Fresh Water 70% of water withdrawn=irrigation
About 57% of irrigated water evaporates or seeps into groundwater
20% of water withdrawn=energy production & industrial processing, cleaning, and waste removal
10% domestic and municipal use
Causes of Freshwater Shortages Dry climate Drought Desiccation Water stress
Causes of Flooding Removal of water
absorbing vegetation Living on floodplains Urbanization-roads,
buildings, parking lots
Reduce Risk of Flooding Channelization Building levees and dams Restoring wetlands Floodplain management to keep people out
of flood prone areas = experts view this as best approach
Increase Water Supplies Dams and reservoirs to store runoff Bringing in surface water from other areas Withdrawing groundwater Desalination Improving the efficiency of water use
Dams and Reservoirs Used to capture and store runoff and release it as
needed to Control flooding Produce electricity Supply water for irrigation Reservoirs used for recreation
1950-2000 number of large dams has increased from 5,700 to more than 45,000
24% of world’s freshwater fish species are threatened or endangered
Dams and Reservoirs cont ½ of the world’s major rivers either run dry
part of the year and fail to reach the sea or have little water left in them
Major rivers that run dry: Colorado, Rio Grande, Yellow in northern China, Nile in the Middle East, Ganges and Indus in South Asia, and Amu Darya and Syr Darya in counties of the former Soviet Union
Transferring Water Uses tunnels, aqueducts, and underground
pipes One of world’s largest transfer projects is
the California Water Project which transfers water to Southern California
Compare the transfer projects for the James Bay Watershed and the Aral Sea
Aral Sea
Advantages of Groundwater Removed as needed Water not lost to evaporation Less expensive to use than surface water
systems Aquifers provide drinking water for 1/3 of
world’s population In U.S. 51% of water used for drinking &
43% used for irrigation
Disadvantages of Groundwater Lowering of water table Depletion of aquifer Aquifer subsidence Intrusion of salt water into aquifers Case Study: Mining Groundwater: The
Shrinking Ogallala Aquifer Ogallala Aquifer
Using Water More Efficiently Reduce water subsidies Use more efficient irrigation practices Xeriscaping-replace green lawns in arid & semiarid
regions with vegetation adapted to that environment Fix water leaks Use water meters & charge for all municipal water
use Raise water prices Water-saving toilets, showerheads, & washers