water resources and water pollution chapter 9. water resources water –earths surface is covered by...

Water Resources and Water Pollution

Water Resources and Water Pollution

Chapter 9

Water ResourcesWater Resources

• Water – Earth’s surface is covered by 71%

water– Essential for life – can survive only a

few days without water

Supply of Water ResourcesSupply of Water Resources

Small fraction (.014%) is readily available for human use

Evaporation and transpiration

Evaporation

Stream

InfiltrationWater tableInfiltration

Unconfined aquifer

Confined aquifer

Lake

Well requiring a pump

Flowingartesian well

Runoff

Precipitation

ConfinedRecharge Area

Aquifer

Less permeable materialsuch as clay Confirming permeable rock layer

Water Cycle – continuously collected, purified, recycled and distributedWater Cycle – continuously collected, purified, recycled and distributed

WatershedWatershed

• A watershed describes the total area contributing drainage to a stream or river

• May be applied to many scales– A large watershed is made up of

many small watersheds

Chehalis Basin

Evaporation and transpiration

Evaporation

Stream

Infiltration

Water tableInfiltration

Unconfined aquifer

Confined aquifer

Lake

Well requiring a pump

Flowingartesian well

Runoff

Precipitation

ConfinedRecharge Area

Aquifer

Less permeable materialsuch as clay

Confirming permeable rock layer

Zone of saturation (spaces completely filled with water)

Water sourcesWater sources

Surface runoff – 2/3 lost to floods and not available for human use.

• Reliable runoff = one third• Amount of runoff that we can count on year to year

Groundwater• Zone of saturation• Water table – top of zone of saturation• Aquifer – water saturated layers of sand,

gravel or bedrock through which groundwater flows.

• Recharge slow ~ 1 meter per year

Use of Water ResourcesUse of Water Resources

Humans directly or indirectly use about 54% of reliable runoff

Withdraw 34% of reliable runoff for:• Agriculture – 70%• Industry – 20%• Domestic – 10%

Leave 20% of runoff in streams for human use:transport goods, dilute pollution, sustain fisheries

Could use up to 70-90% of the reliable runoff by 2025

Too Little WaterToo Little Water

• Problems in the • West

• Dry climate• Drought • Desiccation

Acute shortage

Adequate supply

Shortage

Metropolitan regions with population greater than 1 million

US has plenty of water.Much of it is in the wrongplace at the wrong time.Most serious problems areflooding, pollution, occassional urban shortages

Water conflicts: Western USWater conflicts: Western US

Highly likely conflict potential

Substantial conflict potential

Moderate conflict potential

Unmet rural water needs

Wash.

Oregon

Idaho

Nevada

California

Utah

Montana

Wyoming

Colo.

N.M.

N.D.

S.D.

Neb.

Kansas

Oak.

Texas

Water andFish

Water conflicts: GlobalWater conflicts: Global

Two main factors for water shortage: dry climate and too many people. Many people live in hydro poverty – can’t afford cleanwater.

Too Much Water: FloodsToo Much Water: Floods

• Natural phenomena• Aggravated by human activities

• Rain on snow Living on floodplains• Impervious surfaces• Removal of vegetation• Draining wetlands

Floodplain

Levee Floodwall

Dam

Reservoir

Deforestation and floodingDeforestation and flooding

Using Dams and Reservoirs to Supply More Water: The Trade-offsUsing Dams and Reservoirs to Supply More Water: The Trade-offs

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

Tapping GroundwaterTapping Groundwater

• Year-round use• No evaporation losses• Often less expensive• Potential Problems:

•Water table lowering – too much use•Depletion – U.S. groundwater being

withdrawn at 4X its replacement rate•Saltwater intrusion – near coastal

areas •Chemical contamination•Reduced stream flows

Reducing water wasteReducing water waste

• read section 9-4

SolutionsSustainable Water Use

• Not depleting aquifers• Preserving ecological health of aquatic

systems• Preserving water quality• Integrated watershed management• Agreements among regions and countries

sharing surface water resources• Outside party mediation of water disputes

between nations• Marketing of water rights• Raising water prices• Wasting less water• Decreasing government subsides for

supplying water• Increasing government subsides for reducing

water waste• Slowing population growth

Pollution Source terminologyPollution Source terminology• Point source = pollution comes from

single, fixed, often large identifiable sources – smoke stacks– discharge drains– tanker spills

• Non-point source = pollution comes from dispersed sources– agricultural runoff– street runoff

Types of Water Pollutionfrom Table 9-1 p. 187Types of Water Pollutionfrom Table 9-1 p. 187

• Sediment – logging, roadbuilding, erosion

• Oxygen-demanding wastes– human waste, storm sewers, runoff from

agriculture, grazing and logging, many others

• Nutrient enrichment = Eutrophication– N, P from fertilizers, detergents– leads to increased growth in aquatic systems,

ultimately more non-living organic matter

BODBOD

• As micro-organisms decompose (through respiration) organic matter, they use up all the available oxygen.

• Biological Oxygen Demand (BOD) Amount of oxygen required to decay a certain amount of organic matter.

• If too much organic matter is added, the available oxygen supplies will be used up.

EutrophicationEutrophication

Eutrophic – well-fed, high nutrient levels present in a lake or river

Oligotrophic – poorly-fed, low nutrient levels

Water bodies can be naturally eutrophic or oligotrophic, but can also be human-caused

Types of Water Pollution (con’t)from Table 9-1 p. 187Types of Water Pollution (con’t)from Table 9-1 p. 187• Disease-causing organisms

– from untreated sewage, runoff from feed lots

• Toxic chemicals – pesticides, fertilizers, industrial chemicals

• Heavy metals – lead, mercury

• Acids (to discuss later)• Elevated temperatures = Thermal Pollution

– water is used for cooling purposes, then heated water is returned to its original source

– any increase in temperature, even a few degrees, may significantly alter some aquatic ecosystems.

Groundwater PollutionGroundwater Pollution

• Agricultural products

• Underground storage tanks

• Landfills

• Septic tanks

• Surface

impoundments

Oil SpillsOil Spills

• Exxon Valdez released 42 million liters of oil in Prince William Sound, contaminating 1500 km of Alaska coastline in 1989

• Was the cleanup effective?• Most marine oil pollution comes from non-

point sources: – runoff from streets– improper disposal of used oil– discharge of oil-contaminated ballast water from

tankers

Growth of population Growth of population

• Supply & demand are in growing conflict – supply is finite – water management driven by values and needs

• Increases demand/use of water• Increases land use and changes

vegetation and permeability• Increases demand for instream

values – instream flows are for people

The construction of dams haveslowed the once flowing ColumbiaRiver into a series of lakes.

Agriculture uses approximately 70% of the water withdrawn from our streams and rivers

Changing land use changes vegetation and need for water

Change in land use also changes permeability

Water RightsWater Rights

• Water collectively belongs to the public– Cannot be owned by individuals

• Individuals or groups may be granted rights to use water– Legal authorization to use a predefined

quantity of public water for a designated purpose.• Irrigation, domestic water supply, power

generation

Water RightsWater Rights

• State law requires certain users of public waters to receive approval from the state prior to using water.

• Any use of surface water which began after 1917 requires a water-right permit.

• Withdrawals of underground water from 1945 requires a water-right permit.

Instream flows Instream flows

• Result – the more we know about stream ecology, the more we realize that all the water has instream value, meaning there is no surplus

• Compromises and minimizing impact – thresholds for rate of impact

• Other ways to achieve ecosystem goals – wider view, not just flows – watershed land management

Legal/political aspects of instream flowLegal/political aspects of instream flow

• provide a flow of water sufficient to adequately support food fish and game fish populations in the stream (RCW 77.55.050)

• provide protection and preservation and where possible enhancement, of wildlife, fish, … and other environmental values … (RCW 90.54)

• protect fish, game, birds, and other wildlife, recreational and aesthetic values and water quality (RCW 90.22)

• antidegradation requirements of Washington’s water quality standards (Ch. 173-201 A WAC, following Federal Clean Water Act)

Instream flows Instream flows

• Other ways to achieve ecosystem goals – wider view, not just flows – watershed land management

• Avoid headwater disturbance• Vegetation• Geology and topography• Maintain longitudinal and lateral connectivity• Avoid mainstem in-channel storage • Allow floodplain to function as floodplain

Avoid headwater disturbance and leave vegetation

Allow floodplains to function as floodplains

Flow restoration Flow restoration

• Markets and transfers• Need to protect restored flows • Enforcement

Opportunities Opportunities

• Parks and wilderness areas• Renewable natural resource

management and harvest (forestry, grazing, secondary forest products)

• Municipal watershed protection• Low intensity sustainable

agriculture

Watershed PlanningWatershed Planning

• The 1998 legislature passed ESHB 2514, codified into Ch. 90.82 RCW, to set a framework for developing local solutions to watershed issues on a watershed basis.  Ch. 90.82 RCW states: The legislature finds that the local development of watershed plans for managing water resources and for protecting existing water rights is vital to both state and local interests.

Watershed PlanningWatershed Planning

• RCW 90.82.005• Purpose.• The purpose of this chapter is to develop a more thorough and cooperative method of

determining what the current water resource situation is in each water resource inventory area of thestate and to provide local citizens with the maximumpossible input concerning their goals and objectives forwater resource management and development.

Watershed PlanningWatershed Planning

• Each implementation plan must contain strategies to provide sufficient water for: (a) Production agriculture; (b) commercial, industrial, and residential use; and (c) instream flows. Each implementation plan must contain timelines to achieve these strategies and interim milestones to measure progress