Download 11-1 Will we have enough usable water

11-1 Will we have enough usable water?
CONCEPT 11-1A We are using available freshwater unsustainably by wasting it, polluting it, and charging too
little for this irreplaceable natural resource.
CONCEPT 11-1B One of every six people does not have sufficient access to clean water, and this situation will
almost certainly get worse.
1. Emphasize the importance of water as a chemical substance, and freshwater as a very limited resource.
2. Briefly describe Earth’s water supply and the role of the hydrological cycle. Define groundwater, zone of
saturation, water table, and aquifer. Note the relationship between recharge and nonrenewable aquifers.
3. Define surface water, runoff, watershed/drainage basin, and reliable runoff. Emphasize the relationship
between reliable runoff and freshwater withdrawal rates, and the role of agriculture. Discuss the global
status of water scarcity.
11-2 How can we increase water supplies?
CONCEPT 11-2A Groundwater used to supply cities and grow food is being pumped from aquifers in some areas
faster than it is renewed by precipitation.
CONCEPT 11-2B Using dams, reservoirs, and water transfer projects to provide water to arid regions has increased
water supplies in some areas but has disrupted ecosystems and displaced people.
CONCEPT 11-2C We can convert salty ocean water to freshwater, but the cost is high, and the resulting salty brine
must be disposed of without harming aquatic or terrestrial ecosystems.
1. Assess the environmental effects of groundwater overpumping in order to increase water supplies. Note the
potential role of deep aquifers as a new source of freshwater supplies. Discuss the advantages and
disadvantages of large-scale surface water relocation projects, such as dams. Define desalination, and list
the common desalination methods. Note the disadvantages and advantages of this process for increasing
freshwater supplies.
11-3 How can we use water more sustainably?
CONCEPT 11-3 We can use water more sustainably by cutting water waste, raising water prices, slowing
population growth, and protecting aquifers, forests, and other ecosystems that store and release water.
1. Discuss water losses and waste. List the major reasons for this issue. List the common solutions for
reducing water losses and waste. Explain the benefits of the different types of irrigation.
11-4 How can we reduce the threat of flooding?
CONCEPT 11-4 We can lessen the threat of flooding by protecting more wetlands and natural vegetation in
watersheds and by not building in areas subject to frequent flooding.
1. Define flooding and floodplains. Briefly explain the common causes of flooding. List the major strategies
that can be used to minimize flood risks.
11-5 How can we deal with water pollution?
CONCEPT 11-5A Streams can cleanse themselves of many pollutants if we do not overload them or reduce their
flows.
CONCEPT 11-5B Reducing water pollution requires preventing it, working with nature in treating sewage, cutting
resource use and waste, reducing poverty, and slowing population growth.
1. Define water pollution, and point source and nonpoint source varieties. Note the five major sources of
water pollution. Discuss the status of stream, lake, and reservoir pollution. Define cultural eutrophication as
a form of water pollution. List several ways of dealing with cultural eutrophication. Emphasize why
groundwater is vulnerable to pollution.
2. Emphasize why coastal areas of the oceans are more polluted than the open oceans. Discuss prevention and
source reduction strategies as the best way to reduce water pollution. Emphasize that the U.S. has reduced
water pollution from point sources. Note that sewage treatment in developed countries has helped reduce
nonpoint water pollution. Outline the controversy over strengthening the Clean Water Act in the U.S.
3. Summarize water treatment and purification processes. Note that bottled water is the costly variety of tap
water.