Presentation on theme: "Water Resources and Water Pollution Chapter 9. Water Resources Water –Earths surface is covered by 71% water –Essential for life – can survive only a."— Presentation transcript:
Water Resources and Water Pollution Chapter 9
Water Resources Water –Earths 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
Evaporation and transpiration Evaporation Stream Infiltration Water table Infiltration Unconfined aquifer Confined aquifer Lake Well requiring a pump Flowing artesian well Runoff Precipitation Confined Recharge Area Aquifer Less permeable material such as clay Confirming permeable rock layer Water Cycle – continuously collected, purified, recycled and distributed
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
Evaporation and transpiration Evaporation Stream Infiltration Water table Infiltration Unconfined aquifer Confined aquifer Lake Well requiring a pump Flowing artesian well Runoff Precipitation Confined Recharge Area Aquifer Less permeable material such as clay Confirming permeable rock layer Zone of saturation (spaces completely filled with water)
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 Acute shortage Adequate supply Shortage Metropolitan regions with population greater than 1 million 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
Water 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 and Fish
Water conflicts: Global Two main factors for water shortage: dry climate and too many people. Many people live in hydro poverty – cant afford clean water.
Too Much Water: Floods Natural phenomena Aggravated by human activities Rain on snowLiving on floodplains Impervious surfaces Removal of vegetation Draining wetlands Floodplain Levee Flood wall Dam Reservoir
Deforestation and flooding
Using Dams and Reservoirs to Supply More Water: The Trade-offs Large losses of water through evaporation Large losses of water through evaporation Flooded land destroys forests or cropland and displaces people Flooded land destroys forests or cropland and displaces people Downstream flooding is reduced Downstream cropland and estuaries are deprived of nutrient-rich silt Downstream cropland and estuaries are deprived of nutrient-rich silt 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 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 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 human- caused
Types of Water Pollution (cont) 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.
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 non- point 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 ) 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 Washingtons water quality standards (Ch 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 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 RCW, to set a framework for developing local solutions to watershed issues on a watershed basis. Ch 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.Ch RCW
Watershed Planning RCW 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