Presentation on theme: "Water Supply, Use & Management. Water To understand water, we must understand its characteristics, and roles: Water has a high capacity to absorb and."— Presentation transcript:
Water To 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.
A Brief Global Perspective We are facing a growing global water shortage linked to the food supply. Global hydrologic cycle Transfers water from the atmosphere, to land, to oceans and back to atmosphere 97% in oceans 2% in ice Only 0.001% in atmosphere Video on Water Cycle: Water CycleWater Cycle
A 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 years Amount of water for which all people, animals and plants compete is < 1% Industrial production increases water use Mass of water used 1000x total production of minerals
Groundwater and Streams Groundwater refers to the water below the water table Where saturated conditions exist Locations where surface waters move into the ground are recharge zones Places where it flows or seeps out are discharge zones (points) Area where water seeps through pore spaces known as vadose zone
Groundwater and Streams Aquifer is an underground zone from which groundwater can be obtained When water is pumped from an aquifer forms a cone of depression Aquifer Depletion Video: Aquifer DepletionAquifer Depletion
Streams Effluent stream Flow is maintained during the dry season by seepage Perennial stream Influent stream Entirely above the water table and flows only in direct response to precipitation Ephemeral stream A given stream can have reaches that are both or intermittent at varying times of year.
Interactions Between Surface Water and Groundwater Should be considered part of the same resource. Nearly all surface water environments have linkages w/ ground water E.g. withdrawal of groundwater can lower stream flow or lake levels Pollution can spread from one source to the other
Water 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, transpiration stream flow subsurface flow Water budget A model that balances the inputs, outputs, and storage of water in a system. Precipitation - evaporation = runoff
Water Supply: A US Example Amount of water vapor passing over the US every day ~ 152,000 million m 3 10% falls as precipitation (66% of which is evaporated or transpired) Only 34% enters surface or groundwater
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 low Total storage of runoff not possible because of evaporative losses Precipitation and Runoff Patterns
Droughts Because there are large annual and regional variations in stream flow, even areas with high precipitation and runoff may suffer from droughts.
Groundwater Use and Problems ½ the people in the United States use groundwater as a primary source of drinking water 20% of water used In many parts of the country withdrawal from wells exceeds natural inflow Overdraft Nonrenewable resource Problems include damage to river basins and land subsidence
Desalination as a Water Source Seawater is 3.5% salt Desalination- a technology to remove salt from water Must be reduces to 0.05% to be fresh water Requires large amount of energy, tied to fuel prices Has place value- price increases quickly with transport distance Discharge may affect local salinity Desalination Video: DesalinationDesalination
Water Use Off-stream use Refers to water removed from its source for use May be returned to source after use Or consumptive use-water enters tissues, product or evaporates during use and not returned
Water Use In-stream use The use of the river for navigation, hydroelectric power, fish and wildlife habitats, and recreation. Multiple uses can create controversy
Water Use Another problem with off stream use is how much water can be removed w/o damaging the stream ecosystem. E.g. Aral Sea Diverting water for agriculture caused sea to dry up Surface area of sea reduces 90% in 50 years Aral Sea Video: Aral SeaAral Sea
Transport of Water Ancient civilizations constructed canals and aqueducts to transport water From distant river to where it is needed In modern civilization water moved from areas of abundant rain and snow fall to areas of high usage E.g. California moves water from north to south E.g. New York City has had to obtain water from farther and farther away
Some Trends in Water Use Withdrawal of surface water far exceeds withdrawal of groundwater Since 1980 use has decreased and leveled off Suggests improvement in water management and conservation
Some Trends in Water Use 1. The major uses of water are for irrigation and the thermoelectric industry. 2. Water use for irrigation increased from 1950-1980. It decreased and leveled off from 1985-2000 due to better irrigation efficiency, crop type and higher energy costs. 3. Water use by thermoelectric industry decreased slightly in 1980, and stabilized in 1985. due to reticulating water for cooling 4. Water for public and rural supplies continued to increase through the period from 1950 to 2000 presumably related to the increase in human population.
Water Conservation The careful use and protection of water resources Involves the quantity of water used and the quality Important component of sustainable water use Expected that a number innovations will reduce the total withdrawals
Agricultural Use Improved irrigation could reduce agricultural withdrawals by 20 to 30% Tremendous savings because ag is the biggest user Suggestions for conservation: Price agricultural water to encourage conservation Use 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.
Agricultural Use Irrigate 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.
Domestic Use Accounts for about 10% of total national water withdrawals But concentrated in urban areas May pose major local problems
Domestic 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
Industry and Manufacturing Use Water conservation measures that can be taken by industry: Using cooling towers that use little or no water In-plant water treatment and recycling
Sustainability 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 future without degrading the various components of the hydrologic cycle or the ecological systems that depend on it
Sustainable 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.
Sustainable Water Use Ensure 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.
Groundwater Sustainability Sustainability involves a long term perspective For groundwater even longer Effects of pumping might not be seen immediately Long-term approach involves balancing withdrawal with recharge
Water Management Management 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 regions Options for minimizing potential problems: Alternating water supplies and managing existing supplies better Towing icebergs As price goes up many innovative programs are possible.
A 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 include Drilling to wells that are presently isolated Reuse of waste water Develop surface water and use groundwater in dry years In wet years pump excess surface water underground to recharge groundwater
Water Management and the Environment Often a good deal of controversy surrounds water development Dams, canals, wetlands modification Resolution of development involves input from a variety of government and public groups
Wetlands Wetlands 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 year Have a particular type of vegetation and soil
Wetlands Wetlands - 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: Hydrology Type of vegetation Type of soil
Natural Service Functions of Wetlands Freshwater wetlands are a natural sponge for water. Reducing flooding Many 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.
Wetlands Freshwater wetlands are threatened in many areas. Over the past 200 years > 50% of all wetlands have disappeared, 90% of freshwater wetlands Diked, drained or filled SF bay estuary considered the most modified by human activity
Restoration of Wetlands Number of projects have attempted to restore wetlands. In freshwater marshes recovery linked to availability of water Salt marshes more complex EPA of 1969 states if wetlands destroyed by development must be replaced elsewhere Constructing wetlands to clean up agricultural waste Natural ability to remove excess nutrients, break down pollutants, and cleanse water In Florida, human-made wetlands designed to intercept and hold nutrients so they don’t damage the Everglades.
Dams and the Environment Dams and their accompanying reservoirs generally are designed to be multifunctional structures. Used for recreational activities Generating electricity Providing flood control Ensuring a more stable water supply The environmental effects of dams include the following: Loss of land, cultural resources, and biological resources in the reservoir area Larger, dams and reservoirs produce a potential serious flood hazard should they fail Storage behind the dam of sediment that would otherwise move downstream to coastal areas
Dams 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.
Canals Water from upstream reservoirs may be routed downstream by way of natural water ways or canals and aqueducts. Not hydrologically the same as creeks Smooth, steep banks; water moves fast Canals can spread and carry disease schistosomiasis
Removal of Dams Recent dam removals include Edwards Dam in Maine Marmot Dam in Oregon After removal both river saw return of fish as they migrated upstream Large 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 pools Slower release minimizes damage Matilija 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.
Channelization 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 navigation Adverse environmental effects, including the following: Degradation of the stream’s hydrologic qualities nearly all riffle flow, resulting in loss of important fish habitats Removal of vegetation along the watercourse, which removes wildlife habitats and shading of the water Downstream flooding where the channelized flow ends Damage or loss of wetlands
The 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 US Ends in the Gulf of California
The Colorado River For 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 1922 No water allowed for environmental purposes Water rarely flows into the Gulf, all stored and used upstream. Damaged delta Two largest reservoirs- Hoover Dam and Glen Canyon Dam Stored about 80% of total in the basin Represents a buffer of several years water supply Changing hydrology of the river changed other aspects Rapids, sediment load, and vegetation
The Colorado River Record snowmelt in the Rocky Mountains in 1983 forced the release of water from Glen Canyon Dam Three times normal but similar to spring floods before the dam was built Beneficial to the river, highlighted the importance of floods in maintaining a natural state As an experiment “flood” waters released in 1996 Two weeks at full flood As a result 55 new sandbars formed and 75% of existing sandbars increased in size, rejuvenated marshes and backwaters Hailed a success; hoped that what was learned can help restore other river impacted by dams