2WaterTo understand water, we must understand its characteristics, and roles:Water has a high capacity to absorb and store heat.Water is the universal solvent.Water has a high surface tension.Water is the only compound whose solid form is lighter than its liquid form.Sunlight penetrates water to variable depths, permitting photosynthetic organisms to live below the surface.
3A Brief Global Perspective We are facing a growing global water shortage linked to the food supply.Global hydrologic cycleTransfers water from the atmosphere, to land, to oceans and back to atmosphere97% in oceans2% in iceOnly 0.001% in atmosphereVideo on Water Cycle: Water Cycle
6A Brief Global Perspective At Earth’s surface water can be found in liquid, solid or gaseous form.Residence time varies from a few days to thousands of yearsAmount of water for which all people, animals and plants compete is < 1%Industrial production increases water useMass of water used 1000x total production of minerals
7Groundwater and Streams Groundwater refers to the water below the water tableWhere saturated conditions existLocations where surface waters move into the ground are recharge zonesPlaces where it flows or seeps out are discharge zones (points)Area where water seeps through pore spaces known as vadose zone
8Groundwater and Streams Aquifer is an underground zone from which groundwater can be obtainedWhen water is pumped from an aquifer forms a cone of depressionAquifer Depletion Video: Aquifer Depletion
10Streams Effluent stream Influent stream Flow is maintained during the dry season by seepagePerennial streamInfluent streamEntirely above the water table and flows only in direct response to precipitationEphemeral streamA given stream can have reaches that are both or intermittent at varying times of year.
11Interactions Between Surface Water and Groundwater Should be considered part of the same resource.Nearly all surface water environments have linkages w/ ground waterE.g. withdrawal of groundwater can lower stream flow or lake levelsPollution can spread from one source to the other
13Water Supply: A U.S. Example Water supply at any point on the land surface depends on several factors in the hydrologic cycle,including the rates of precipitation, evaporation, transpirationstream flowsubsurface flowWater budgetA model that balances the inputs, outputs, and storage of water in a system.Precipitation - evaporation = runoff
15Water Supply: A US Example Amount of water vapor passing over the US every day ~ 152,000 million m310% falls as precipitation (66% of which is evaporated or transpired)Only 34% enters surface or groundwater
17Precipitation and Runoff Patterns In developing water budgets for water resources management it is useful to consider annual precipitation and runoff patterns.Potential problems can be predicted in areas where average runoff and precipitation lowTotal storage of runoff not possible because of evaporative losses
18DroughtsBecause there are large annual and regional variations in stream flow, even areas with high precipitation and runoff may suffer from droughts.
19Groundwater Use and Problems ½ the people in the United States use groundwater as a primary source of drinking water20% of water usedIn many parts of the country withdrawal from wells exceeds natural inflowOverdraftNonrenewable resourceProblems include damage to river basins and land subsidence
21Desalination as a Water Source Seawater is 3.5% saltDesalination- a technology to remove salt from waterMust be reduces to 0.05% to be fresh waterRequires large amount of energy, tied to fuel pricesHas place value- price increases quickly with transport distanceDischarge may affect local salinityDesalination Video: Desalination
22Water Use Off-stream use Refers to water removed from its source for useMay be returned to source after useOr consumptive use-water enters tissues, product or evaporates during use and not returned
23Water Use In-stream use The use of the river for navigation, hydroelectric power, fish and wildlife habitats, and recreation.Multiple uses can create controversy
25Water UseAnother problem with off stream use is how much water can be removed w/o damaging the stream ecosystem.E.g. Aral SeaDiverting water for agriculture caused sea to dry upSurface area of sea reduces 90% in 50 yearsAral Sea Video: Aral Sea
30Transport of WaterAncient civilizations constructed canals and aqueducts to transport waterFrom distant river to where it is neededIn modern civilization water moved from areas of abundant rain and snow fall to areas of high usageE.g. California moves water from north to southE.g. New York City has had to obtain water from farther and farther away
31Some Trends in Water Use Withdrawal of surface water far exceeds withdrawal of groundwaterSince 1980 use has decreased and leveled offSuggests improvement in water management and conservation
32Some Trends in Water Use The major uses of water are for irrigation and the thermoelectric industry.Water use for irrigation increased from It decreased and leveled off fromdue to better irrigation efficiency, crop type and higher energy costs.Water use by thermoelectric industry decreased slightly in 1980, and stabilized in 1985.due to reticulating water for coolingWater for public and rural supplies continued to increase through the period from 1950 to 2000presumably related to the increase in human population.
35Water Conservation The careful use and protection of water resources Involves the quantity of water used and the qualityImportant component of sustainable water useExpected that a number innovations will reduce the total withdrawals
36Agricultural UseImproved irrigation could reduce agricultural withdrawals by 20 to 30%Tremendous savings because ag is the biggest userSuggestions for conservation:Price agricultural water to encourage conservationUse lined or covered canals that reduce seepage and evaporation.Use computer monitoring and schedule release of water for maximum efficiency.Integrate the use of surface water and groundwater to more effectively use the total resource.
37Agricultural UseIrrigate at times when evaporation is minimal, such as at night or in the early morning.Use improved irrigation systems, such as sprinklers or drip irrigation, that more effectively apply water to crops.Improve the soil to increase infiltration and minimize runoff.Encourage the development of crops that require less water or are more salt tolerant.
40Domestic UseAccounts for about 10% of total national water withdrawalsBut concentrated in urban areasMay pose major local problems
41Domestic Use Water use can be substantially reduced by: In semiarid regions, replace lawns with decorative gravels and native plants.Use more efficient bathroom fixtures.Turn off water when not absolutely needed.Flush the toilet only when really necessary.Fix all leaks quickly.Purchase dishwashers and washing machines that minimize water consumption.Take a long bath rather than a long shower.Sweep sidewalks and driveways.Using gray water to water vegetation.Water lawns and plants at cool times to reduce evaporation.Use drip irrigation and place water-holding mulch around garden plants.Plant drought-resistant vegetation.Learn how to read the water meter to monitor for unobserved leaks and record your conservation successes.Use reclaimed water
42Industry and Manufacturing Use Water conservation measures that can be taken by industry:Using cooling towers that use little or no waterIn-plant water treatment and recycling
43Sustainability and Water Management From a water supply use and management perspective, sustainable water use defined as:use of water resources by people in a way that allows society to develop and flourish into an indefinite futurewithout degrading the various components of the hydrologic cycle or the ecological systems that depend on it
44Sustainable Water Use General criteria: Develop water resources in sufficient volume to maintain human health and well-being.Provide sufficient water resources to guarantee the health and maintenance of ecosystems.Ensure minimum standards of water quality for the various users of water resources.
45Sustainable Water UseEnsure that actions of humans do not damage or reduce long-term renewability of water resources.Promote the use of water-efficient technology and practice.Gradually eliminate water pricing policies that subsidize the inefficient use of water.
46Groundwater Sustainability Sustainability involves a long term perspectiveFor groundwater even longerEffects of pumping might not be seen immediatelyLong-term approach involves balancing withdrawal with recharge
47Water ManagementManagement of water resources is a complex issue that will become more difficult as demand for water increases in the coming years.Especially in areas like the Southwestern US and other semi arid regionsOptions for minimizing potential problems:Alternating water supplies and managing existing supplies betterTowing icebergsAs price goes up many innovative programs are possible.
49A Master Plan for Water Management New management philosophy is that surface water and groundwater are both subject to natural flux with time.In wet years, there is plenty of surface water, and the near- surface groundwater resources are replenished.During dry years, specific plans to supply water on an emergency basis must be in place and ready to use.Advanced planning may includeDrilling to wells that are presently isolatedReuse of waste waterDevelop surface water and use groundwater in dry yearsIn wet years pump excess surface water underground to recharge groundwater
50Water Management and the Environment Often a good deal of controversy surrounds water developmentDams, canals, wetlands modificationResolution of development involves input from a variety of government and public groups
51WetlandsWetlands is a comprehensive term for landforms such as salt marshes, swamps, bogs, prairie potholes, and vernal pools.Common feature is that they are wet at least part of the yearHave a particular type of vegetation and soil
52WetlandsWetlands - defined as areas that are inundated by water or where the land is saturated to a depth of a few cm for at least a few days per year.Three major components used to determine the presence of wetlands are:HydrologyType of vegetationType of soil
53Natural Service Functions of Wetlands Freshwater wetlands are a natural sponge for water.Reducing floodingMany freshwater wetlands are important as areas of groundwater recharge or discharge.Wetlands are one of the primary nursery grounds for fish, shellfish, aquatic birds, and other animals.Wetlands are natural filters that help purify water.Wetlands are often highly productive and are places where many nutrients and chemicals are naturally cycled.Coastal wetlands provide a buffer for inland areas from storms and high waves.Wetlands are an important storage site for organic carbon.
54Wetlands Freshwater wetlands are threatened in many areas. Over the past 200 years > 50% of all wetlands have disappeared, 90% of freshwater wetlandsDiked, drained or filledSF bay estuary considered the most modified by human activity
55Restoration of Wetlands Number of projects have attempted to restore wetlands.In freshwater marshes recovery linked to availability of waterSalt marshes more complexEPA of 1969 states if wetlands destroyed by development must be replaced elsewhereConstructing wetlands to clean up agricultural wasteNatural ability to remove excess nutrients, break down pollutants, and cleanse waterIn Florida, human-made wetlands designed to intercept and hold nutrients so they don’t damage the Everglades.
56Dams and the Environment Dams and their accompanying reservoirs generally are designed to be multifunctional structures.Used for recreational activitiesGenerating electricityProviding flood controlEnsuring a more stable water supplyThe environmental effects of dams include the following:Loss of land, cultural resources, and biological resources in the reservoir areaLarger, dams and reservoirs produce a potential serious flood hazard should they failStorage behind the dam of sediment that would otherwise move downstream to coastal areas
57Dams and the Environment Downstream changes in hydrology and in sediment transport that change the entire river environment and the organisms that live there.Fragmentation of ecosystems above and below a dam.Restrict movement upstream and downstream or organic material, nutrients and aquatic organisms.
58CanalsWater from upstream reservoirs may be routed downstream by way of natural water ways or canals and aqueducts.Not hydrologically the same as creeksSmooth, steep banks; water moves fastCanals can spread and carry diseaseschistosomiasis
59Removal of DamsRecent dam removals includeEdwards Dam in MaineMarmot Dam in OregonAfter removal both river saw return of fish as they migrated upstreamLarge fish runs transport nutrients upriver from ocean to forest ecosystems.Trapped sediment behind dams must be dealt with in dam removal.If released quickly it could damage downstream ecosystem and fill poolsSlower release minimizes damageMatilija Dam in Ventura County cost $300,000 to build but 10 times that to remove.Removing dams is simple in concept but involves complex problems relating to sediment and water.
61Channelization and the Environment Channelization of streams consists of straightening, deepening, widening, clearing, or lining existing stream channels.Engineering technique that has been used to control floods, improve drainage, control erosion, and improve navigationAdverse environmental effects, including the following:Degradation of the stream’s hydrologic qualitiesnearly all riffle flow, resulting in loss of important fish habitatsRemoval of vegetation along the watercourse, which removes wildlife habitats and shading of the waterDownstream flooding where the channelized flow endsDamage or loss of wetlands
62The Colorado River: Water Resources Management and the Environment The history of the Colorado River emphasizes linkages among physical, biological, and social systems that are at the heart of environmental science.Major river of the southwestern USEnds in the Gulf of California
63The Colorado RiverFor its size has a modest flow but is one of the most regulated and controversial bodies of water in the world.Total flow was apportioned among various users in 1922No water allowed for environmental purposesWater rarely flows into the Gulf, all stored and used upstream.Damaged deltaTwo largest reservoirs- Hoover Dam and Glen Canyon DamStored about 80% of total in the basinRepresents a buffer of several years water supplyChanging hydrology of the river changed other aspectsRapids, sediment load, and vegetation
64The Colorado RiverRecord snowmelt in the Rocky Mountains in 1983 forced the release of water from Glen Canyon DamThree times normal but similar to spring floods before the dam was builtBeneficial to the river, highlighted the importance of floods in maintaining a natural stateAs an experiment “flood” waters released in 1996Two weeks at full floodAs a result 55 new sandbars formed and 75% of existing sandbars increased in size, rejuvenated marshes and backwatersHailed a success; hoped that what was learned can help restore other river impacted by dams