water: a limited resource chapter 14. the importance of water water: shapes continents moderates our...
TRANSCRIPT
Water: A Limited Resource
Chapter 14
The Importance of Water
Water:
• shapes continents
• moderates our climate
• is essential for all living organisms
The Importance of Water
Properties of Water
Composition and polarity
Hydrogen bonding properties
The Importance of Water
Properties of Water
Chemical composition of seawater
The Importance of Water
The Hydrologic Cycle
The Importance of Water
Our Supply of Fresh Water
The Importance of Water
Types of water:
• surface water
• runoff
• drainage basin
• groundwater
• aquifers
The Importance of Water
Largest watersheds
The Importance of Water
Aquifers
Water Use and Resource Problems
Problems fall into 3 categories:
• Too much
• Too little
• Poor quality / contamination (Chap. 22)
Water Use and Resource Problems
Too Much Water
Removing vegetation and constructing buildings increases flooding potential on flood plains
Water Use and Resource Problems
Too Much Water
Flood Management
Channelization
Water Use and Resource Problems
Too Much Water
Flood Management
Levees with natural river
Water Use and Resource Problems
Case-in-Point: The Floods of 1993
Water Use and Resource Problems
Too Little Water
• Droughts
• Overdrawing Surface Waters
• Aquifer depletion
– Causes subsidence
– Can lead to saltwater intrusion
Water Use and Resource Problems
Saltwater intrusion
Water Use and Resource Problems
Too Little Water
• Droughts
• Overdrawing Surface Waters
• Aquifer depletion
– Causes subsidence
– Can lead to saltwater intrusion
• Salinization of Irrigated Soil
Average annual precipitation
Water Problems in the US
Surface Water
Most problems in the West and Southwest
Aqueducts transport water from distance sources
Water Problems in the US
Examples of problems:
• Mono Lake
• The Colorado River
Basin
Surface Water
Water Problems in the US
Groundwater
Aquifer depletion
Water Problems in the US
Groundwater
Aquifer depletion
- Ogallala Aquifer
Global Water Problems
• Water distribution globally is very inequitable
In addition, stable runoff varies
• Drinking Water Problems
1.4 billion lack safe water
2.9 billion lack proper wastewater disposal
Global Water Problems
Population Growth and Water Problems
• India – 8,000 villages have no local water
• China – water table falling 2-3 m / year
• Pakistan – lack of water led to riots in 2001
• Mexico – water table falling 3.5 m / year in Mexico City
Global Water Problems
Sharing Water Resources among Countries
The Rhine River Basin
Global Water Problems
Sharing Water Resources among Countries
The Aral Sea
19761997
Global Water Problems
Potentially Volatile International Water Situations
–Jordan River
–Nile River
Sharing Water Resources among Countries
Water Management
Providing a Sustainable Water Supply
Sustainable water use seeks to provide water to future generations without damaging ecosystems.
Water Management
Providing a Sustainable Water Supply
Dams and ReservoirsPros –• Ensure year-round water
supply• Hydropower• Recreation
Water Management
Providing a Sustainable Water Supply
Dams and ReservoirsCons –• Alter ecosystems• Sediment Deposition
Water Management
Providing a Sustainable Water Supply
Dams and Reservoirs
Example: Effect of dam on Colorado River in Grand Canyon
Water Management
Providing a Sustainable Water Supply
Water Diversion Projects
Water Management
Providing a Sustainable Water Supply
DesalinizationTwo methods:1) Distillation
Condenses
Simplified process:
Salt water
Pure water is collected
Water boiled
Produces steam
Water Management
Providing a Sustainable Water Supply
DesalinizationTwo methods:1) Distillation2) Reverse osmosis
Salt water
H2O
salt
Pressure Fresh water
Salt impermeable membrane
Water Conservation
Reducing Agricultural Water Waste
Drip or trickle irrigation
Water Conservation
Reducing Agricultural Water Waste
Reducing Water Waste in Industry
Reducing Municipal Water Waste
Recycling water Xeriscaping