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)


Importance of Water

Cooking & washing Agriculture Manufacturing Mining Energy production Waste disposal Use of freshwater is

increasing


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


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


Hydrologic Cycle


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


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


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)


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


Urban vs. Pre-Urban Floodplains


Floodplains

Rather than rebuild levees adjacent to rivers, experts suggest allowing some flooding of floodplains during floods.

Government restrictions on building Levees can fail


Left: Traditional levees adjacent to river

Right: Suggested levee style, set back from river


Floods of Summer 2008


Levees produce major challenges


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


Too Little Water

Saltwater Intrusion


Water Problems In US and Canada

Overall, US has a plentiful supply of freshwater

Many areas have a 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- 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


Colorado River bed in Mexico


Water Problems in US and Canada- Groundwater Aquifer Depletion


Water Problems in US and Canada- Groundwater Ogallala Aquifer

High Plains Water withdrawn for

agriculture faster than nature replaces it


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



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



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)



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


Aral Sea


1976 2010

Water Management

Main Goal: Provide sustainable supply of high-quality water Dams and Reservoirs Water Diversion Projects Desalinization


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


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


Dams and Reservoirs


Dams and Reservoirs

Salmon Population in Columbia R. very low due to dams that impede migration

Fish ladders help, but are not effective enough


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


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


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

Reducing Industrial Water Waste Stricter laws provide incentive to conserve water Water scarcity encourages further industrial

recycling Potential to conserve water is huge


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


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


13 Water. Overview of Chapter 13 Importance of Water Water Use and Resource Problems Water...

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