chapter 9: water resources. flooding- both natural and human induced. modern floods are highly...
TRANSCRIPT
Chapter 9: Water Resources
• Flooding- both natural and human induced.
• Modern floods are highly destructive because humans have:− Removed water-absorbing plant
cover from soil.− Constructed buildings on floodplains
• Floodplain- area bordering a river channel that has the potential to flood
Too much water: Flooding
Urban vs. pre-Urban Floodplains
Floodplains
• Rather than rebuild levees adjacent to rivers, experts suggest allowing some flooding of floodplains during floods
Traditional levees adjacent to river
Suggested levee style, set back from river
Too Little Water
• Typically found in arid land• Problems• Drought• Overdrawing water for irrigation purposes• Aquifer depletion• Subsidence• Sinkholes• Saltwater intrusion
NOTE: shown are center-pivot irrigation circles…each one is the
result of long pipes that extend along the radius from the center of the
circle to the edge…rotating slowly to spray the crops.
Subsidence
Subsidence- occurs when large amounts of ground water have been removed from certain types of rocks.
Sinkhole
Sinkholes- Sinkholes are depressions or holes in the land surface, they can be shallow or deep, small or large, but all are a result of the dissolving of the underlying limestone.
• Agriculture- the largest user of water around the world
~70%
Agriculture, Industry and Household Needs
• Irrigation techniques-− Furrow irrigation- a trench that is flooded
with water.
− Flood irrigation- the entire field is flooded with water.
− Spray irrigation- an apparatus that sprays water across a field.
− Drip irrigation- using a slow dripping hose that is laid on or buried beneath the soil.
− Hydroponic agriculture- crops grown in fertilized water and no soil.
Agriculture, Industry and Household Needs
• Industry- the second largest user of water worldwide.
Agriculture, Industry and Household Needs
• Households- the third largest user of water worldwide .
Agriculture, Industry and Household Needs
• US has a plentiful supply of freshwater
• However, water is NOT uniformly distributed, so many areas have severe shortages• Geographical
variations• Seasonal
variations
Water Problems in US and Canada
• Water shortages in West and Southwest• Water is diverted and transported via aqueducts
Water Problems in US and Canada
• Mono Lake (Eastern CA)• Rivers and streams that once fed this lake
are diverted to Los Angeles (275mi away)• Becoming highly saline• Court ordered water diversion reduction
• Colorado River Basin• Provides water for 27-million people• Numerous dams for Hydropower• Colorado River no longer reaches ocean
• Delaware – a state without water• Use of conservation-based pricing, in which
consumers are rewarded for conserving water is helping water managers meet needs
Water Problems in US and Canada
Colorado River bed in Mexico
Groundwater (Aquifer) Depletion
Water Problems in US and Canada
Reducing Agricultural Water Waste• Agriculture is very inefficient with water• Microirrigation- irrigation that conserves
waster by piping to crops through sealed systems• Also called drip or trickle irrigation
Water Conservation
Reducing Industrial Water Waste• Stricter laws provide incentive to
conserve water• Recycling water within the plant
• Water scarcity (in addition to stricter pollution control requirements) will encourage further industrial recycling
• Potential to conserve water is huge!
Water Conservation
• Amount of freshwater on planet CAN meet human needs− BUT, it is unevenly distributed and
some places lack stable runoff• Problems:
− Climate Change− Drinking Water− Population Growth− Sharing Water Resources Among
Countries
Global Water Problems
• Water and Climate Change− Climate change affects the type and
distribution of precipitation− Potential issues:
−Reduced snowfall will impact water resources downstream
−Sea level rise will cause saltwater intrusion into drinking water supplies
Global Water Problems
• Rhine River Basin − Countries upstream discharged pollutants into river− Countries downstream had to pay to clean the
water before they could drink it
• Aral Sea− Water diversion for irrigation has caused sea to
become too saline
Sharing Water Resources
1967 1997
• Water ownership- people can have rights to water use, but they do not own the water.
• Water conservation- using techniques such as more efficient water fixtures, faucets and washing machines.
The Future of Water Availability
• Gray water- wastewater from baths, showers, bathroom sinks and washing machines.− While not suitable for drinking, gray water is
perfectly suitable for watering lawns and plants, washing cars, and flushing toilets
Working toward Sustainability
• Install water-saving shower heads and faucets
• Install low-flush toilets
• Fix leaky fixtures
• Purchase high efficiency appliances
• Modify personal habits
• Use the dishwasher instead of washing by hand
Conserving water at Home