Transcript Document

Water Resources and
Water Pollution
Chapter 9
Water Resources
• Water
– Earth’s surface is covered by 71% water
– Essential for life – can survive only a few
days without water
Supply of Water Resources
Small fraction (.014%) is readily
available for human use
Water Cycle – continuously collected,
purified, recycled and distributed
Flowing
artesian well
Precipitation
Well requiring a pump
Evaporation and transpiration
Evaporation
Confined
Recharge Area
Runoff
Aquifer
Infiltration
Stream
Water table
Infiltration
Lake
Unconfined aquifer
Less permeable material
such as clay
Confined aquifer
Confirming permeable rock layer
Watershed
• 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
Flowing
artesian well
Precipitation
Evaporation and transpiration
Well requiring a pump
Evaporation
Confined
Recharge Area
Runoff
Aquifer
Infiltration
Stream
Water table
Lake
Infiltration
Zone of saturation
(spaces completely filled with water)
Unconfined aquifer
Confined aquifer
Less permeable material
such as clay
Confirming permeable rock layer
Water 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 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 Water
• Problems in the
• West
• Dry climate
• Drought
• Desiccation
US has plenty of water.
Much of it is in the wrong
place at the wrong time.
Most serious problems are
flooding, pollution,
occassional urban shortages
Acute shortage
Adequate supply
Shortage
Metropolitan regions with
population greater than 1 million
Water conflicts: Western US
Water and
Fish
Wash.
Montana
N.D.
Oregon
S.D.
Idaho
Wyoming
Neb.
Nevada
Colo.
Utah
Kansas
California
Oak.
N.M.
Texas
Highly likely conflict potential
Substantial conflict potential
Moderate conflict potential
Unmet rural water needs
Water conflicts: Global
Two main factors for water shortage: dry climate and too
many people. Many people live in hydro poverty – can’t afford clean
water.
Too Much Water: Floods
• Natural phenomena
• Aggravated by human activities
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Rain on snow
Impervious surfaces
Removal of vegetation
Draining wetlands
Living on floodplains
Reservoir
Dam
Levee
Floodplain
Flood
wall
Deforestation and flooding
Using Dams and Reservoirs to
Supply More Water: The Trade-offs
Flooded land destroys
forests or cropland and
displaces people
Large losses
of water through
evaporation
Downstream cropland and
estuaries are deprived of
nutrient-rich silt
Downstream flooding
is reduced
Reservoir is useful for
recreation and fishing
Can produce cheap electricity (hydropower)
Migration and spawning of some fish are disrupted
Provides water
for year-round
irrigation of
cropland
Tapping Groundwater
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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 waste
• read section 9-4
Solutions
Sustainable Water Use
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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 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 Pollution
from 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
BOD
• 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.
Eutrophication
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 humancaused
Types 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 Pollution
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Agricultural products
Underground storage tanks
Landfills
Septic tanks
Surface
impoundments
Oil 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 nonpoint sources:
– runoff from streets
– improper disposal of used oil
– discharge of oil-contaminated ballast water from
tankers
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 have
slowed the once flowing Columbia
River 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 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 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
• 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 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
• 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
• Markets and transfers
• Need to protect restored flows
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Enforcement
Opportunities
• Parks and wilderness areas
• Renewable natural resource
management and harvest (forestry,
grazing, secondary forest products)
• Municipal watershed protection
• Low intensity sustainable agriculture
Watershed 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 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 the
state and to provide local citizens with the maximum
possible input concerning their goals and objectives for
water resource management and development.
Watershed 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