Water Resources, Consumption, and

Conservation

Do NowAnswer the following in your journals

1. Water is a precious resource. Explain what this means.

2. What is the structure of water and what are the properties of water that make it essential for life?

3. Is water a renewable or nonrenewable resource? Defend your answer.

4. What are the two types of water resources?5. What are the three main uses of water?

Water ResourcesWater is essential to life on Earth. Humans can live for more than month without food.

Think & Record in your journals!How long can we live without water?

Special Properties of Water• Polarity “The Universal Solvent”

Dissolves substances Nutrient & waste transport; Chemical weathering

• Polarity Hydrogen Bonding Adhesion, cohesion, surface tension Nutrient/water transport via capillary action into roots and through plants Supports insects- food for aquatic life

• Solid state less dense than the liquid state– Expands when freezes & floats; Protects aquatic life

• Wide temperature range for water in the liquid state

– Encompasses annual mean T of most ecological environments– Maintains flow/transport ability in many environments

Special Properties of Water• Filters UV

– Protects aquatic life– Allowed early life to evolve until ozone

layer formed– Greenhouse gas

• High heat capacity (specific heat)– Large amount of energy needed to raise

the temp of 1 gram by 1 degree celsius– Large bodies of water act as buffers

against extreme climate fluctuations– Protects organisms against sudden

environmental T change• High heat of vaporization

– Energy required to convert lg– Evaporation helps distribute heat globally– Provides means for organisms to cool

Water- A Renewable Resource

Water is considered a renewable resource because it is circulated- it continuously moves between Earth & the atmosphere.

Think & Record in your journal!What is the continuous movement of water between Earth & the atmosphere called?

The Water CycleContinuous movement of water between Earth & it’s

atmosphere

Earth The Water Planet

Not called the “Blue Planet for nothing!

~70% of Earth is covered in water

Why then, is water a limited resource that we need to conserve?

Global Water Usage and Supply

• Water usage 1.6 X 10 15 gallons/year• Water supplies

– 1.2 X 10 16 gallons from run off to surface water (lakes, rivers, streams)

– 3.0 X 10 16 infiltrated into aquifers

What is the difference between global water supply and usage (demand)? Calculate now!

Global Water Usage and Supply

• Water usage 1.6 X 10 15 gallons/year• Water supplies

– 1.2 X 10 16 gallons from run off to surface water (lakes, rivers, streams)

– 3.0 X 10 16 infiltrated into aquifers

(4.2 X 10 16 ) – (0.16 X 10 16 ) = 4.04 X 10 16 A SURPLUS!

So, why is access to water globally an issue?

Water Distribution & Degradation• There is uneven distribution of water globally

– 25% of global run off goes into the Amazon River Basin– So geographically, water is not readily available to

everyone equally– Even if water is available, distribution, transport, delivery

are an issue in some parts of the world (Developing vs. developed countries & Infrastructure)

• All water is not potable– Water pollution/degradation causes less water to be fit

for human consumption (availability of surface water vs groundwater sources; infrastructure to treat surface water)

Water Treatment

• There must be infrastructure to deliver water and to make water potable or suitable for drinking.

• Water treatment removes elements such as mercury, arsenic, and lead, which are poisonous to humans even in low concentrations.

• These elements are found in polluted water, but they can also occur naturally in groundwater.

Water Treatment

• Pathogen – viruses, microorganisms, or other substances that cause disease- can be found in water contaminated by sewage or animal feces.

• Pathogens can be removed with water treatment.• Explore the EPA links below to explore…

EPA Water Treatment Process Explanation for kids:http://water.epa.gov/learn/kids/drinkingwater/watertreatmentplant_index.cfmEPA Tour of a Wastewater Treatment Center:http://www.epa.gov/ogwdw/watertreatmentplant/flash/index.html

Wastewater Treatment

Wastewater Treatment

Surface Water SourcesEx. Ponds, Lakes, Rivers, Streams, Watersheds,

Wetlands

Used for drinking, irrigation, fishing, transportation, and industry

Surface Water:WatershedsAn area of land drained (surface run off) by a water system

Watersheds come in all shapes and sizes. They cross county, state, and national boundaries.

In the continental US, there are 2,110 watersheds; including Hawaii Alaska, and Puerto Rico, there are 2,267 watersheds.

Earth’s Major Watersheds

What is the most prominent watershed in the United States?

Another view Mississippi River Basin

Amazon River Watershed

Another ViewAmazon River Watershed

Hackensack Passaic Watersheds

Benefits of Watersheds• Improved water quality- filter pollutants, promote nutrient

cycling, and help retain sediment.• Carbon storage- intact natural land cover and soil resources are

capable of sequestering carbon, offsetting GHG emissions.• Increased resilience in the face of climate change threats.• Reduced risk for invasive species colonization- more resilient and

can favor indigenous species, helping them out-compete invasive species.

• Reduced drinking water treatment and infrastructure costs- filter pollutants and protect water quality.

• Reduced flood mitigation costs- minimize the area and impacts of floods, reduce the burden on public drainage infrastructure, and increase groundwater recharge.

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Surface Water:Wetlands• Regions of wet topographic depression• Land covered by water all or part of the year• Any region of saturated soil- tidal and

freshwater• Boundary between terrestrial/aquatic

biomes and poorly drained depression• Sustains vegetation adapted to saturated

soil

Surface Water:Wetlands

• Wetlands used to be considered wasteland for disease-carrying insects• Many were drained, filled, and cleared for farms or

residential and commercial development.• The Florida Everglades used to cover 8 million

acres; now cover less than 2 million acres

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Benefits of Wetlands1. They trap and filter sediments, nutrients, and pollutants,

keeping them from entering lakes and oceans2. They reduce flooding, protect agriculture, roads, buildings, and

human health and safety3. They buffer shorelines against erosion4. They provide spawning grounds and habitat for commercially

important fish and shellfish5. They provide habitat for rare, threatened, and endangered

species6. They provide recreational areas for fishing, bird-watching,

hiking, canoeing, photography, …

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Groundwater• A large percentage of fresh water that is available

for human use exists underground.• The water is carried down through rocks and soil

from rain is stored as groundwater in an aquifer.

• The water table is the upper boundary of an aquifer that indicates level of saturation.

 

Groundwater in Aquifers

Groundwater & Water Table Levels• In wet regions, the water table may be at Earth’s surface. • In deserts, the water table may be hundreds of meters

beneath Earth’s surface

• Area where rocks/soil are permeable to allow water to collect is called a recharge zone.

• Development prevents recharge zones from recharging! Pollution pollutes them!

• Use of water faster than it can be recharged is dangerous. Wells will need to be dug deeper.

Aquifers & Recharging

Groundwater & Wells

• A well is a hole that is dug or drilled to reach groundwater.• We dig wells because some rural areas are not connected to the

municipal water system & ground water may be a more reliable source of water than surface water because it is filtered and purified as it travels underground.

Groundwater, Aquifers, & Wells

Water Consumption and

Conservation

Global Water Use

• Estimated that 2/3 global water use by humans is “wasted” through evaporation/leakage

• Most effective way to force conservation might be

– Raise prices

– Water meter for every user

– Subsidize conservation projects rather than water development projects

U.S. Geological Survey Circular 1268, “Estimated Use of Water in the United States in 2000”.

Biggest user or water?

How do we access and extend our water resources?

Conservation MethodsTraditional Methods•Dam construction•Diversion projects•Pumping groundwaterOther Alternative Methods•Desalination

Industrial Water Use• Most of the water that is used in

industry is used to cool power plants Thermoelectric!

• Power-plant cooling systems usually pump water from a surface water source such as a river or a lake, carry the water through pipes in a cooling tower, and then pump the water back into the source.

• The water that is returned is usually warmer than the source, but is generally clean and can be used again.

Agricultural Water UseAgriculture accounts for the biggest water user

Plants require a lot of water to grow, and as much as 80 percent of the water used in agriculture evaporates.

In the US we irrigate to grow grains to feed to livestock! •7 billion livestock in the U.S.- as much as people globally- and they eat 5X grain!•Al grain current fed to livestock could feed nearly 3X the US population.

Irrigation A method of providing plants with water from sources other than

direct precipitation. Traditional methods…

• High evaporation loss

• Reduced if irrigating at night

Renault D and Wallender W. 2000. Nutritional Water Productivity and Diets, Agricultural Water Management. v. 45 p. 275-296

Water Conservation in AgricultureMost efficient new methods…

Most of the water loss in agriculture comes from evaporation, seepage, and runoff.

•Low Energy Precision Application (LEPA) Sprinkers.

– System of spraying close to the ground

•Drip Irrigation Systems– Deliver small amounts of water directly to

plant roots by using perforated tubing.

•Both can be monitored by computer

Residential Water UseDomestic water use accounts for about 10% of US water withdrawal.

There are striking differences in residential water use throughout the world. The average person in the United States uses about 300 L of water a day.

Think & record in your journal!How do you think we use residential water? Be specific.How do you think our water usage compares to the average person in India’s usage?How can we conserve our water usage?

Indoor household water use

Data from U.S. Environmental Protection Agency, 2003.

Most US water use occurs in the bathroom…

Conservation?

Reusing gray water

A Turkish inventor has designed a washing machine that pipes the relatively clean water left over from a washing machine, termed gray water, to a toilet, where it can be reused for flushing. Such technologies can reduce the amount of drinkable water used and the volume of water going into sewage treatment plants.

Figure 9.25

Residential Water Use

• Landscape with native plants suited to climate

• Use graywater or collected rainwater for irrigation

• Fix leaks• Install low flow appliances• Other?

Water Conservation at

Home

Residential Water Use

There are striking differences in residential water use throughout the world. The average person in the United States uses about 300 L of water a day.

Think & record in your journal!How do you think our water usage compares to the India’s usage? On average- 41L water/person in India.

How do we access and extend our water resources?

Conservation Methods

Traditional Methods•Dam construction•Diversion projects•Pumping groundwaterOther Alternative Methods•Desalination

Humans and Water Management

• People often live in areas where the natural distribution of surface water is inadequate.

• For thousands of years, humans have altered streams and rivers to make them more useful.– Aqueducts– Canals– Dams– Reservoirs

Aqueducts

• Ancient aqueducts- bridges constructed to convey water over an obstacle (ravine or valley) to a city.

• Modern aqueducts- Underground channel to convey water from one location to another.

DamsA Dam is a structure that is built across a river to control a

it’s flow. Interrupting a river’s flow can have consequences.

Think & record in your journal!What do you think those might be?

ReservoirsA Reservoir is an artificial body of water that usually forms behind a

dam.

Water from a reservoir can be used for flood control, drinking water, irrigation, recreation, and industry.

What’s the dam controversy?Dams are functional:•Generate inexpensive, renewable power (7-10% in US)•Reduce flooding hazards•Provide reservoir recreation•Provide irrigation water•In the past 50 yrs, dam construction has increased water supply to humans by ~30%•Presently, ~70,000 dams w/heights >6ft

Dam problems:•Threaten/endanger ¼ of all FW fish species

– Destroy migration routes or separate local populations

•Alter water characteristics (flow, temp, and composition)

– Flowing standing – Increase in temperature– Sedimentation build up

upstream– Reduced nutrient/sediment

flow downstream– Flooding upstream

Removal of the Roberts Street DamRaritan River, New Jersey

newswatch.nationalgeographic.com

In regions of solid rock aquifers: Cones of depression lead to lowering of the water table. Aquifer can recharge if over pumping is remedied

Over pumping Groundwater

The Ogallala Aquifer

Slow RechargeThe Ogallala Aquifer

has very slow recharge

Average remaining thickness of water =

60 m

Water withdrawal causes a decline of approximately 0.6

m/yr

Saltwater IntrusionIn coastal regions: If the pumping of fresh water out of a well is

faster than the recharge salt water can infiltrate the aquifer.

SinkholesIn regions of cavernous limestone:

A large sinkhole collapsed in Winter Park, FL in 1981. The city

stabilized and sealed the sinkhole, converting it to a 350 ft wide

urban lake.

In regions of unconsolidated sediments:

USGS scientist shows subsidence from 1925-1977 in the San Joaquin Valley, CA.

From USGS Professional Paper 1401-A, "Ground water in the Central Valley, California”

Photo by Dick Ireland, USGS, 1977

Subsidence

How do we access and extend our water resources?

Conservation MethodsTraditional Methods•Dam construction•Diversion projects•Pumping groundwater

Other Alternative Methods•Desalination

Desalination(a)Distillation uses heat to convert pure water into steam that is later

condensed, leaving the salt behind.

Desalination(b) Pressure pushes the water through a semi-permeable

membrane, leaving the salt behind.

DesalinationRemoving salt from ocean water

• UAE World’s largest ~80 billion gal/year- Distillation

• Florida (Distillation) and Texas (Osmosis) ~10 billion gal/year

• The process consumes a lot of energy & is too expensive for many nations to consider.

Desalination plant in UAE

Other Solutions for the FutureTransporting water from other regions

• In some areas of the world water is transported by ships.– Enormous plastic bags filled with fresh water are towed– Water is pumped where it’s needed– Ex. Greek Islands

• Alaska contains ½ the US available fresh water– Alaska California being considered