discussion of various components of hydro cycle…
surface water – lakes, streams, overland flow
groundwater – subsurface flow, some water in aquifers may be thousands of years old…..
how much of the world’s water supply are we using?
Water use has increased almost 10x since 1900….biggest use is irrigation
70% goes to irrigated land
20% goes to industry
10% goes to cities and industries
Miller makes point that US has plenty of water, but it is in the “wrong place” or it is getting contaminated (example of Long Island aquifer, supporting 3 million people)
Imbalance: plenty water in eastern US, not enough in western US
Western US uses lots of water for irrigation, but does NOT get much through recharge. So there is the danger of a net loss of water…..especially since people continue to move out west….
14-3 – too little water
Dessication of soil
Stress is low per capita (per person) availability of water
Build dams & reservoirs to store water
Bring in water from elsewhere
Increase GW withdrawal
Desalinate salt water
Improve efficiency of use of existing water supplies