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Transcript of 13 Water. Overview of Chapter 13 Importance of Water Water Use and Resource Problems Water...
13 Water
Overview of Chapter 13
Importance of Water Water Use and Resource Problems Water Problems in US and Canada Global Water Problems Water Management Water Conservation
© 2012 John Wiley & Sons, Inc. All rights reserved.
Importance on APES test
Earth Systems and Resources (10-15%)
Global Water Resources and Use(Freshwater/saltwater; agricultural, industrial, and domestic use; surface and groundwater issues; global problems; conservation)
© 2012 John Wiley & Sons, Inc. All rights reserved.
Importance of Water
Cooking & washing Agriculture Manufacturing Mining Energy production Waste disposal Use of freshwater is
increasing
© 2012 John Wiley & Sons, Inc. All rights reserved.
Properties of Water
Composed of 2 Hydrogen and 1 oxygen
Exists as solid, liquid or gas
High heat capacity Polar Forms Hydrogen bond
between 2 water molecules H-bonds define water’s
physical properties© 2012 John Wiley & Sons, Inc. All rights reserved.
Properties of Water
Water is never completely pure in nature
Content of seawater (left)
Many substances water dissolves cause water pollution
© 2012 John Wiley & Sons, Inc. All rights reserved.
Distribution of Water
Only 2.5% of water on earth is freshwater 2% of this in the
form of ice Only ~0.5% of
water on earth is available freshwater
© 2012 John Wiley & Sons, Inc. All rights reserved.
Hydrologic Cycle
© 2012 John Wiley & Sons, Inc. All rights reserved.
Freshwater Terminology
Surface water Precipitation that remains on the surface and does not seep into
soil
Runoff Movement of surface water to lakes, rivers, etc.
Watershed (drainage basin) Land area that delivers water into a stream or river system
Groundwater Freshwater under the earth’s surface stored in aquifers
Aquifer Underground caverns and porous layers of sand, gravel and
rock in which groundwater is stored
© 2012 John Wiley & Sons, Inc. All rights reserved.
Mississippi River Watershed is the largest in U.S.How does a cattle farmer in Montana potentially impact a shrimp fisherman in Louisiana?
RIVER SYSTEM
Did You Know?Did You Know? The Mississippi River Basin covers 3 The Mississippi River Basin covers 3 million square kilometers (1.2 million sq mi), making it million square kilometers (1.2 million sq mi), making it the third largest watershed in the world. It drains 41% the third largest watershed in the world. It drains 41% of the land area of the contiguous US.of the land area of the contiguous US.
Did You Know?Did You Know? The Mississippi River Basin covers 3 The Mississippi River Basin covers 3 million square kilometers (1.2 million sq mi), making it million square kilometers (1.2 million sq mi), making it the third largest watershed in the world. It drains 41% the third largest watershed in the world. It drains 41% of the land area of the contiguous US.of the land area of the contiguous US.
World’s River Systems and Watershed
GroundwaterGroundwater
As precipitation infiltrates and percolates through voids in soil and rock Pores, fractures, crevices, etc.
Shallow rock has little moisture Zone of saturation is at a depth were
ground is filled with water Top of this zone is water table.
Falls in dry weather Rises in wet weather
Aquifer
Important source of water Porous, water-saturated layers of sand, gravel
or bedrock through which groundwater flows Area of land that supplies water to aquifer is
called the recharge area Natural recharge is when water percolates
downward, but sometimes lateral recharge occurs
Freshwater Aquifer
© 2012 John Wiley & Sons, Inc. All rights reserved.
Aquifer: a water-bearing rock formation
Porosity
How much space (pores) or holes found in rock
Where water can flow through
Porous rock can hold lots of water
Water Use and Resource Problems
Fall into Three Categories Too much water Too little water Poor quality/contamination (addressed in Chapter 21)
© 2012 John Wiley & Sons, Inc. All rights reserved.
Too Much Water
Flooding Both natural and human-induced
Modern floods are highly destructive Humans have removed water-absorbing plant
cover from soil Humans construct buildings on floodplains
Floodplain Area bordering a river channel that has the
potential to flood
© 2012 John Wiley & Sons, Inc. All rights reserved.
Urban vs. Pre-Urban Floodplains
© 2012 John Wiley & Sons, Inc. All rights reserved.
Floodplains
Rather than rebuild levees adjacent to rivers, experts suggest allowing some flooding of floodplains during floods.
Government restrictions on building Levees can fail
© 2012 John Wiley & Sons, Inc. All rights reserved.
Left: Traditional levees adjacent to river
Right: Suggested levee style, set back from river
© 2012 John Wiley & Sons, Inc. All rights reserved.
Floods of Summer 2008
© 2012 John Wiley & Sons, Inc. All rights reserved.
Levees produce major challenges
© 2012 John Wiley & Sons, Inc. All rights reserved.
Floodwaters can no longer add fertility to flood plains by depositing sediment
Sediments are carried farther downstream and settle out where the river enters the ocean.
Prevent flooding at one location, but they force floodwater farther downstream and cause worse flooding.
Levees break due to pressure which was what happened during Hurricane Katrina in 2005 in New Orleans
Too Little Water
Typically found in arid land Problems
Drought Overdrawing water for irrigation purposes Aquifer depletion
Subsidence Sinkholes
© 2012 John Wiley & Sons, Inc. All rights reserved.
Too Little Water
Saltwater Intrusion
© 2012 John Wiley & Sons, Inc. All rights reserved.
Water Problems In US and Canada
Overall, US has a plentiful supply of freshwater
Many areas have a severe shortages Geographical
variations Seasonal
variations
© 2012 John Wiley & Sons, Inc. All rights reserved.
Water Problems In US and Canada
Water shortages in West and Southwest Water is diverted and transported via aqueducts
© 2012 John Wiley & Sons, Inc. All rights reserved.
Water Problems in US and Canada- Surface Water
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
© 2012 John Wiley & Sons, Inc. All rights reserved.
Colorado River bed in Mexico
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Water Problems in US and Canada- Groundwater Aquifer Depletion
© 2012 John Wiley & Sons, Inc. All rights reserved.
Water Problems in US and Canada- Groundwater Ogallala Aquifer
High Plains Water withdrawn for
agriculture faster than nature replaces it
© 2012 John Wiley & Sons, Inc. All rights reserved.
WYOMING SOUTH DAKOTA
NEBRASKA
COLORADO
KANSAS
OKLAHOMA
NEW MEXICO
TEXAS
0 100Miles
Kilometers
Less than 61 meters (200 ft)
61-183 meters (200-600 ft)
More than 183 meters (600 ft)(as much as 370 meters or 1,200 ft.in places)
0 160
Ogallala Aquifer:World’s largest known aquifer. (If all water from this aquifer was on the surface, it would cover all 50 states with 1.5 feet of water!) Being severely depleted over time.
Global Water Problems
Amount of freshwater on planet CAN meet human needs BUT, it is unevenly distributed and some places
lack stable runoff Problems:
Weather and Climate Drinking Water Population Growth Sharing Water Resources Among Countries
© 2012 John Wiley & Sons, Inc. All rights reserved.
Global Water Problems
Water and Climate 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
© 2012 John Wiley & Sons, Inc. All rights reserved.
Global Water Problems
Drinking Water Problems Many developing countries have insufficient water
to meet drinking and household needs 1.1 billion people lack access to safe drinking
water Population Growth
Increase in population means an increase in freshwater requirements
Limits drinking water available Limits water available for agriculture (food)
© 2012 John Wiley & Sons, Inc. All rights reserved.
Global Water Problems
Sharing Water Resources Among Countries Rhine River Basin (right)
Countries upstream discharged pollutants into river
Countries downstream had to pay to clean the water before they could drink it
Aral Sea (next slide) Water diversion for irrigation
has caused sea to become too saline
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Aral Sea
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1976 2010
Global Water Problems
© 2012 John Wiley & Sons, Inc. All rights reserved.
Water Management
Main Goal: Provide sustainable supply of high-quality water Dams and Reservoirs Water Diversion Projects Desalinization
© 2012 John Wiley & Sons, Inc. All rights reserved.
Dams and Reservoirs
Benefits: Ensure year-round supply
of water with regulated flow Generate electricity Provide recreational
activities Disadvantages
Alter the ecosystem Reduce sediment load
© 2012 John Wiley & Sons, Inc. All rights reserved.
Upstream of Dams - Negative Impact
Environment Loss of terrestrial habitat and species Creation of artificial (lakes) system Exotic species introductions Reservoir/storage for contaminants
Cultural / social Loss of cultural resources Displacement of families (villages,
regions) Water quality hazard
Economic Shift in land use / economy Water loss via evaporation Water loss via seepage
Aesthetic landscape inundated
Downstream Impacts of Dams
Altered hydrology - no seasonality Altered water quality/character Modify nutrient cycling Reduce sediment supply Channel adjustments Habitat modification Species impacts River fragmentation
Dams and Reservoirs
Glen Canyon Dam Powerful spring floods brought sediment, which
created sandbar habitat Regulated flow is detrimental to wildlife To rectify this, government started flooding the
Grand Canyon periodically starting in 1996
© 2012 John Wiley & Sons, Inc. All rights reserved.
Dams and Reservoirs
© 2012 John Wiley & Sons, Inc. All rights reserved.
Dams and Reservoirs
Salmon Population in Columbia R. very low due to dams that impede migration
Fish ladders help, but are not effective enough
© 2012 John Wiley & Sons, Inc. All rights reserved.
Large lossesof water throughevaporation
Large lossesof water throughevaporation
Flooded land destroys forests or cropland anddisplaces people
Flooded land destroys forests or cropland anddisplaces people
Downstream flooding is reducedDownstream flooding is reduced
Downstream cropland andestuaries are deprived ofnutrient-rich silt
Downstream cropland andestuaries are deprived ofnutrient-rich silt
Reservoir is useful for recreation and fishing
Can produce cheap electricity (hydropower)
Migration and spawning of some fish are disruptedMigration and spawning of some fish are disrupted
Provides waterfor year-roundirrigation ofcropland
Pros and Cons of Dams
Water Diversion Projects
Water diverted to areas that are deficient
Much of Southern CA receives its water supply from diverted water from Northern CA
Controversial and expensive
© 2012 John Wiley & Sons, Inc. All rights reserved.
Desalinization
Removal of salt from ocean or brackish water Two methods:
Distillation - salt water is evaporated, and water vapor is condensed into freshwater
Reverse Osmosis- involves forcing salt water through a membrane permeable to water, but not salt
Very expensive
© 2012 John Wiley & Sons, Inc. All rights reserved.
Desalinization
Removing salt from salt water
Has a lot of promise Very energy
intensive Very expensive What to do with
waste? Future?
Water Conservation
Reducing Agricultural Water Waste 4 types of irrigation.
Furrow irrigation - Dig trenches along the crop rows and fill them with water.
Flood irrigation involved flooding an entire field with water. More disruptive to plant growth.
Spray irrigation- Water is pumped from a well into an apparatus that contains a series of spray nozzles that spray water across the field.
Micro-irrigation - irrigation that conserves waster by piping to crops through sealed systems. AKA drip or
trickle irrigation.© 2012 John Wiley & Sons, Inc. All rights reserved.
Water Conservation
Drip irrigation© 2012 John Wiley & Sons, Inc. All rights reserved.
Furrow irrigation
FloodIrrigation
Spray Irrigation
Water Conservation
Reducing Industrial Water Waste Stricter laws provide incentive to conserve water Water scarcity encourages further industrial
recycling Potential to conserve water is huge
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Water Conservation
Reducing Municipal Water Waste
Gray Water Can be used to flush
toilets, wash car or water lawn
Water saving household fixtures
Government incentives
© 2012 John Wiley & Sons, Inc. All rights reserved.
Conserving at Home
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
© 2012 John Wiley & Sons, Inc. All rights reserved.