lecture04_water1

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Geography 210: Physical Geographyand Environmental Issues

Water Supply, Use, and Management

Dr. Bryan Mark & Fletcher Chmara-Huff

AU 2006LECTURE #4

This is WATER week

Water on Earth Where is it, and in what form?

Fresh water on the continents (S&S 15)

How does water get (re)cycled? What impacts the availability of usable water?

Issues of water management & supply

Stream flow and flooding

Local water issues

Wetlands: form, function, remediation FIELD TRIP FRIDAY!!! Dress appropriately

The USEPA National Wetlands

OfficeIts Role in Wetland

Policy and ProtectionDoreen M. Vetter

Special Assistant for Water

Office of the Administrator

U.S. Environmental Protection Agency

Friday October 6, 2006

1:30-2:30 pm

Heffner Wetland Building Lobby

Olentangy River Wetland Research Park

Whats special about H2O?

Heat capacity

Universal solvent

High surface tension

Exists in all 3 phases at normal Earthsurface temperatures

Solid H2O is lighter than the liquid H2O

Sunlight penetrates water

Global water supply & distribution

97% in oceans 2% in glaciers

1% elsewhere Groundwater

Lakes

Rivers, streams

Atmosphere (0.001%)

Abundance is not theproblem, delivering enoughwhen its needed is.

Hydrological

Cycle

Reservoirs

Fluxes


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Freshwater vs. saltwater

97.5 % of all water on Earth is saline

Remaining 2.5 percent is freshwater

~75% in Antarctic and Greenland ice sheets ~24% as fossil groundwater.

Only 0.26% is accessible

lakes, reservoirs, rivers and streams

0.007% water on Earth is renewable andavailable for use on a sustainable basis.

Water usage:A global perspective

Water usage accelerating, globally 1975: 700 km3/y 2002: 6000 km3/y demand for water to sustain, feed, and employ the

world's people is projected to double by 2025. Compared to other minerals, water is

inexpensive Usage is 1000 x that of all other mineral

production Usage is now a significant fraction of that

available Usage is on-sustainable in many regions of the

world

Domestic water use

Our societyconsumes 50-100 gallonsper person,per day.

This pie chartshows how anaverage homein Akron, OHuses water(src: USGS).

Figure 15.28, S&S p. 538

Future water shortage

> 50% of humanity will face watershortages within 50 years, UN report,January 2003 "water-stressed" countries

US will overuse available surface waterresources by 13% in 2020, USWRC

$400 billion /year global industry

Privatization Water, The Next Oil?

Desalinization: A viable option? Removes salt from water

Filtration: forcing saline waterthrough salt-impermeablemembranes

Each m3 of sea water contains 40kg(88 lb) of salt

Salinity = 4%.

>500 desal plants now exist.

Cost-prohibitive

10x that of existing water supplyin US

Requires large amounts ofenergy.

Environmental issue

What to do with the very saltywater coming out of the desalplant?

Desalinization plant in Saudi Arabia

the hydrologic cycle of water from the oceans and the continents to theatmosphere through evapotranspiration; back to the ocean and continentsurfaces through precipitation and eventually returning to the oceansthrough surface runoff (rivers) after storage (lakes, ground water, icesheets) Figure 15.1, p. 513

Hydrologic cycle


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Quantifying water supply

Water Budget: model balancing inputs &outputs

Simple annual budget : (Precipitation Evaporation Infiltration = Runoff)

Useful in water resource management

Supply is NEVER greater than runoff

Large year to year variations inprecipitation rate & stream flow

Even humid regions can have drought

US Water Budget

Average annualprecipitation (in)

Potential

evapotranspiration(in)

Large year to year variations in precipitation rate

Precipitation is variable

Droughts happen

That sucks

Loss of land fertility

Crop failure

Famine Potential

Water ResourceManagement

Continental fresh water:location & management issues

1. Ground water

2. Surface water


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Groundwater & surface water flow system

Water table

Precip falling on land:

1. Evapotranspiration

2. Runoff

3. Infiltration

Percolation through soil water,unsaturated zone, water table

2003 John Wiley and Sons Publishers

Groundwater Occurs below the water

table, where the soil issaturated

Aquifer = undergrnd zonewhere water can be

extracted at useful rate Depletion by wells

causes drawdown a coneof depression in the watertable

As many wells exploit anaquifer, their cones ofdepression merge tocreate a general loweringof the water table S&S Figure 15.12, p. 519

Ground Water Contamination

S&S Figure 15.13, p. 520

Surface-Groundwater interactions

~1/2 Americans use groundwater as primarydrinking water

accounts for 20% of US water usage

Overdraft: when discharge (output) > recharge(input)

Problems: land subsidence, salt water intrusion

Groundwater issues The Ogallala Aquifer

Composed of water bearing sandsand gravel, i.e. groundwater

filled during melt of ice sheet in lastice age.

current 20 x overdraft, -> 1.74 feetper year (1,082,631 acre ft).

North Plains GroundwaterConservation District(http://www.npwd.org)

Ground

water

mining


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Subsidence:

Groundwater

level changes

as a result of

pumping in the

Texas-

Oklahoma

High Plains

region.


Salt water intrusion

Depletion ofgroundwater causes acone of depression in

the water table andcan lead to salt waterintrusion if along acoastal site

Surface Water

the relative magnitude of discharge of major rivers in the United States

S&S Figure 15.17, p. 524

Sources of stream flow

Measuring stream discharge (Q)

Q = A * V

Hydrograph


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Urbanization effect Hydrograph fluctuations

normal rangebase flow

Flooding

Most universallyexperienced naturalhazard.

Floodplain

Urbanization andflooding

Land use planning

Water Use and Management

Off-stream use: removed from source,returned

Consumptive use: removed, but notreturned

In-stream use: navigation, hydro power,habitats, recreation

Water Resource Management

Stream diversions

In stream uses

Conflicting demands throughout the year


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Trends in U.S. usage (1950-95)

Surface water w/drawl >> ground water

Trends by category

Major use: irrigationand thermoelectric

Irrigation use leveledby ~1980

Industry use declinedafter ~1980

Public and ruralsupply use increased(POPULATION)

Irrigation and land use

Center-pivot irrigation systems,source: KSU Geography

Landsat TM satellite image showing leafchlorophyll reflectance in red, source: KSUGeography

The Aral Sea

is drying up

and dying as

a result of

diversion of

water for

agriculture.


output> input

The AralSea'svolume hasdecreasedby 75percent , theequivalent ofdrainingLakes Erieand Ontario.

Water Conservation

is the careful use and protection ofwater resources.

Involves both quality and quantity.

Improved agricultural irrigation couldreduce w/drawl by 20-30%; how?

Price water to encourage conservation

Use lined or covered canals to reduceseepage and evaporation


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2003 John Wiley and SonsPublishers

Comparison of

agricultural

practices in

1990 with what

they might by

by 2020.

Water Conservation: Domestic Use

only 10% of nationalwater usage

Most consumed inbathroom & clotheswashing

Concentrated urbanpopulations

How to conserve?

Xeriscaping (i.e. no greenlawns in AZ!)

Wetlands

Important ecologically and aesthetically

Defined: areas inundated by water; or where landis saturated to a depth of a few cm a few days/yr

Functions: Water (and carbon) storage; groundwater recharge

Natural filters (kidneys) Highly productive ecosystems (habitats)

Flood control

Why bother retaining/restoringwetlands?

1. Reduce downstreamflooding

2. Purify water3. Sites of concentrated

nutrient cycling4. Groundwater recharge5. Nursery grounds for fish,

shellfish, birds and otheranimals

6. 45% of endangeredanimals depend onwetlands

7. Coastal wetlands formbarrier to storm surges

8. Aesthetically pleasing

Can wetlands be restored?

1% of US wetlands are lost every 2 yrs;est. 90% of total freshwater lost in 200 yrs

Compensatory restoration required byNational Environmental Policy Act of 1969

Legal success ecological success

Self-design as ecosystem property: naturalprocesses contribute to speciesintroduction and selection

Dams and the Environment

Considerable environmental effects:

Loss of land, cultural resources, biology

Sediment storage behind dam

Downstream changes in hydrology andsediment transport impact riverenvironment and organisms


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Case study:Dam removal

in ME

Summary

Water enables life

Water we can use is a t iny fraction of total on Earth

Water supply & usage involves many interactions; awater budget is needed

Water consumption will likely increase with population,even as w/drawl decreases slightly

Water w/drawl conflicts with in-stream needs

Groundwater use and overuse has resulted in problems

Water use for agriculture is most significant area forconservation

Summary (cont.)

Wetlands are important components at the ecosystemlevel, benefiting people and other ecosystems

Flooding is perhaps the most universal hazard in theworld, enhanced by urbanization; best approached withland-use planning

We are facing a growing water shortage

"Thousands have lived

without love, not onewithout water."

-- W. H. Auden

lecture04_water1

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