CHAPTER 17 Water Use and Management 370 Learning Outcomes ...

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22 févr. 2014 (il y a 3 années et 3 mois)

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Chapter 17: Water Use

and Management

Surface Water, Bosnia

17.1 Water Resources


The hydrologic cycle constantly redistributes
water


Water
supplies are unevenly distributed

The Hydrologic Cycle

17.2 Major Water Compartments


Oceans hold 97 percent of all water on earth


Glaciers
, ice, and snow contain most surface
fresh water
(69%)


Groundwater
Stores
Large Resources (30%)


Rivers
, lakes, and wetlands cycle quickly
(1%)


The
atmosphere is among the smallest of
compartments
(1 ppm)


17.3 Water Availability And Use


Many Countries Suffer Water Scarcity And
Water Stress


Water Consumption Is Less Than Withdrawal


Withdrawal: What’s Taken Out. Much May Return
Quickly To Source


Some Returned Water May Be Degraded


Consumed: Not Easily Returnable To Source


Very Little Water Is Actually Destroyed


What Is Destroyed Is Easily Reconstituted


17.3 Water Availability And Use


Water Use Is Increasing


Agriculture Is The Greatest Water Consumer
Worldwide


Water Recycles Quickly But Not Necessarily Where
It Came From


Domestic And Industrial Water Use Are
Greatest In Wealthy Countries


17.4 Freshwater Shortages


Many people lack access to clean water


Groundwater
is being depleted


Climate
change threatens water supplies


Rivers
are shrinking


Would
you fight for water?

All
-
Time Life Savers


Clean Water


Food Preservation


Antiseptics


Antibiotics


Vaccination


Surgery


Green revolution


Mosquito Control

Green Bay Case Study

Deep Aquifers of the Green Bay Area


Green Bay Piezometric Surface

1957 1960

Green Bay Piezometric Surface

1957 2003

The Russian Radioactive Waste
Injection Program

Center
-
Pivot Irrigation

Center
-
Pivot Irrigation

Some Places Have Too Much Water

Soluble Rocks

Karst in Wisconsin

Geothermal Systems: Mammoth Hot
Springs, Yellowstone

Yellowstone Canyon

Old Faithful Geyser, Yellowstone

17.5 Dams And Diversions


Dam failure can be disastrous


Dams
often displace people and damage
ecosystems


Dams
kill fish


Sedimentation
limits reservoir life


What
Do You Think? Should We Remove
Dams?


Near end of useful life


Too small to contribute meaningfully

Banqiao Dam Failures, China, 1975


Built 1950’s for power and flood control


Hydrologist critical of design was sacked,
reinstated, and sacked again


Designed to survive 1000 year flood (30 cm =
12 inches rain per day)


In 1975, >2000 year flood occurred


19 cm (8 inches) in one hour


106 cm (40 inches) in one day

Banqiao Dam Failures, China, 1975


August 1975: Cold Front collides with Super
Typhoon Nina


Delay in opening gates because of
communications failures and concern about
downstream flooding


Gates blocked by sediment


August 8, 12:30 AM: Dam upstream fails


Designed for 500 year flood but exceeded capacity

Banqiao Dam Failures, China, 1975


August 8, 1 AM, Banqiao Dam overtopped and
failed


Precipitated the failure of 62 dams


Flood wave 10 km wide, 3
-
7 m high, moving
50 km/hour


Numerous dams opened by air strikes to
control flow

Banqiao Dam Failures, China, 1975


One commune of 9600 people was entirely
annihilated


26,000 people died from flooding


145,000 died from subsequent epidemics and
famine.


9 days after the flood a million people were
still stranded


About 6,000,000 buildings collapsed


Details declassified in 2005

Banqiao Dam After Failure

17.7 Increasing Water Supplies


Desalination Provides Expensive Water


Domestic Conservation Can Save Water


Recycling Can Reduce Consumption


Prices And Policies Have Often Discouraged
Conservation (Encouraged Waste)


What Can You Do? Saving Water And
Preventing Pollution

Desalination


Passive Distillation


Slow


Active Distillation


Energy Intensive


Reverse Osmosis


Energy Intensive


Fragile Filters

Reverse Osmosis