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Water Resources, Consumption, and Conservation. Do Now Answer the following in your journals. Water is a precious resource . Explain what this means. What is the structure of water and what are the properties of water that make it essential for life?
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Do NowAnswer the following in your journals • Water is a precious resource. Explain what this means. • What is the structure of water and what are the properties of water that make it essential for life? • Is water a renewable or nonrenewable resource? Defend your answer. • What are the two types of water resources? • What are the three main uses of water?
Water Resources Water is essential to life on Earth. Humans can live for more than month without food. Think & Record in your journals! • How long can we live without water?
Special Properties of Water • Polarity “The Universal Solvent” • Dissolves substances • Nutrient & waste transport; Chemical weathering • Polarity Hydrogen Bonding • Adhesion, cohesion, surface tension • Nutrient/water transport via capillary action into roots and through plants • Supports insects- food for aquatic life • Solid state less dense than the liquid state • Expands when freezes & floats; Protects aquatic life • Wide temperature range for water in the liquid state • Encompasses annual mean T of most ecological environments • Maintains flow/transport ability in many environments
Special Properties of Water • Filters UV • Protects aquatic life • Allowed early life to evolve until ozone layer formed • Greenhouse gas • High heat capacity (specific heat) • Large amount of energy needed to raise the temp of 1 gram by 1 degree celsius • Large bodies of water act as buffers against extreme climate fluctuations • Protects organisms against sudden environmental T change • High heat of vaporization • Energy required to convert lg • Evaporation helps distribute heat globally • Provides means for organisms to cool
Water- A Renewable Resource Water is considered a renewable resource because it is circulated- it continuously moves between Earth & the atmosphere. Think & Record in your journal! What is the continuous movement of water between Earth & the atmosphere called?
The Water CycleContinuous movement of water between Earth & it’s atmosphere
Earth The Water Planet Not called the “Blue Planet for nothing! ~70% of Earth is covered in water • Why then, is water a limited resource that we need to conserve?
Global Water Usage and Supply • Water usage 1.6 X 10 15 gallons/year • Water supplies • 1.2 X 10 16 gallons from run off to surface water (lakes, rivers, streams) • 3.0 X 10 16 infiltrated into aquifers What is the difference between global water supply and usage (demand)? Calculate now!
Global Water Usage and Supply • Water usage 1.6 X 10 15 gallons/year • Water supplies • 1.2 X 10 16 gallons from run off to surface water (lakes, rivers, streams) • 3.0 X 10 16 infiltrated into aquifers (4.2 X 10 16) – (0.16 X 10 16) = 4.04 X 10 16 A SURPLUS! So, why is access to water globally an issue?
Water Distribution & Degradation • There is uneven distribution of water globally • 25% of global run off goes into the Amazon River Basin • So geographically, water is not readily available to everyone equally • Even if water is available, distribution, transport, delivery are an issue in some parts of the world (Developing vs. developed countries & Infrastructure) • All water is not potable • Water pollution/degradation causes less water to be fit for human consumption (availability of surface water vs groundwater sources; infrastructure to treat surface water)
Water Treatment • There must be infrastructure to deliver water and to make water potable or suitable for drinking. • Water treatment removes elements such as mercury, arsenic, and lead, which are poisonous to humans even in low concentrations. • These elements are found in polluted water, but they can also occur naturally in groundwater.
Pathogen – viruses, microorganisms, or other substances that cause disease- can be found in water contaminated by sewage or animal feces. Pathogens can be removed with water treatment. Explore the EPA links below to explore… Water Treatment EPA Water Treatment Process Explanation for kids: http://water.epa.gov/learn/kids/drinkingwater/watertreatmentplant_index.cfm EPA Tour of a Wastewater Treatment Center: http://www.epa.gov/ogwdw/watertreatmentplant/flash/index.html
Surface Water SourcesEx. Ponds, Lakes, Rivers, Streams, Watersheds, Wetlands Used for drinking, irrigation, fishing, transportation, and industry
Surface Water:Watersheds An area of land drained (surface run off) by a water system Watersheds come in all shapes and sizes. They cross county, state, and national boundaries. In the continental US, there are 2,110 watersheds; including Hawaii Alaska, and Puerto Rico, there are 2,267 watersheds.
Earth’s Major Watersheds What is the most prominent watershed in the United States?
Benefits of Watersheds • Improved water quality- filter pollutants, promote nutrient cycling, and help retain sediment. • Carbon storage- intact natural land cover and soil resources are capable of sequestering carbon, offsetting GHG emissions. • Increased resilience in the face of climate change threats. • Reduced risk for invasive species colonization- more resilient and can favor indigenous species, helping them out-compete invasive species. • Reduced drinking water treatment and infrastructure costs- filter pollutants and protect water quality. • Reduced flood mitigation costs- minimize the area and impacts of floods, reduce the burden on public drainage infrastructure, and increase groundwater recharge.
Surface Water: Wetlands • Regions of wet topographic • depression • Land covered by water all or part of the year • Any region of saturated soil- tidal and freshwater • Boundary between terrestrial/aquatic biomes and poorly drained depression • Sustains vegetation adapted to saturated soil
Surface Water:Wetlands • Wetlands used to be considered wasteland for disease-carrying insects • Many were drained, filled, and cleared for farms or residential and commercial development. • The Florida Everglades used to cover 8 million acres; now cover less than 2 million acres
Benefits of Wetlands • They trap and filter sediments, nutrients, and pollutants, keeping them from entering lakes and oceans • They reduce flooding, protect agriculture, roads, buildings, and human health and safety • They buffer shorelines against erosion • They provide spawning grounds and habitat for commercially important fish and shellfish • They provide habitat for rare, threatened, and endangered species • They provide recreational areas for fishing, bird-watching, hiking, canoeing, photography, …
Groundwater • A large percentage of fresh water that is available for human use exists underground. • The water is carried down through rocks and soil from rain is stored as groundwater in an aquifer. • The water table is the upper boundary of an aquifer that indicates level of saturation.
Groundwater & Water Table Levels • In wet regions, the water table may be at Earth’s surface. • In deserts, the water table may be hundreds of meters beneath Earth’s surface
Aquifers & Recharging • Area where rocks/soil are permeable to allow water to collect is called a recharge zone. • Development prevents recharge zones from recharging! Pollution pollutes them! • Use of water faster than it can be recharged is dangerous. Wells will need to be dug deeper.
Groundwater & Wells • A well is a hole that is dug or drilled to reach groundwater. • We dig wells because some rural areas are not connected to the municipal water system & ground water may be a more reliable source of water than surface water because it is filtered and purified as it travels underground.
Global Water Use • Estimated that 2/3 global water use by humans is “wasted” through evaporation/leakage • Most effective way to force conservation might be • Raise prices • Water meter for every user • Subsidize conservation projects rather than water development projects
Biggest user or water? U.S. Geological Survey Circular 1268, “Estimated Use of Water in the United States in 2000”.
How do we access and extend our water resources? Conservation Methods Traditional Methods • Dam construction • Diversion projects • Pumping groundwater Other Alternative Methods • Desalination
Industrial Water Use • Most of the water that is used in industry is used to cool power plants Thermoelectric! • Power-plant cooling systems usually pump water from a surface water source such as a river or a lake, carry the water through pipes in a cooling tower, and then pump the water back into the source. • The water that is returned is usually warmer than the source, but is generally clean and can be used again.
Agricultural Water Use Agriculture accounts for the biggest water user Plants require a lot of water to grow, and as much as 80 percent of the water used in agriculture evaporates. In the US we irrigate to grow grains to feed to livestock! • 7 billion livestock in the U.S.- as much as people globally- and they eat 5X grain! • Al grain current fed to livestock could feed nearly 3X the US population.
Irrigation A method of providing plants with water from sources other than direct precipitation. Traditional methods… • High evaporation loss • Reduced if irrigating at night
Renault D and Wallender W. 2000. Nutritional Water Productivity and Diets, Agricultural Water Management. v. 45 p. 275-296
Water Conservation in AgricultureMost efficient new methods… Most of the water loss in agriculture comes from evaporation, seepage, and runoff. • Low Energy Precision Application (LEPA) Sprinkers. • System of spraying close to the ground • Drip Irrigation Systems • Deliver small amounts of water directly to plant roots by using perforated tubing. • Both can be monitored by computer
Domestic water use accounts for about 10% of US water withdrawal. There are striking differences in residential water use throughout the world. The average person in the United States uses about 300 L of water a day. Think & record in your journal! How do you think we use residential water? Be specific. How do you think our water usage compares to the average person in India’s usage? How can we conserve our water usage? Residential Water Use
Indoor household water use Most US water use occurs in the bathroom… Conservation? Data from U.S. Environmental Protection Agency, 2003.
Reusing gray water A Turkish inventor has designed a washing machine that pipes the relatively clean water left over from a washing machine, termed gray water, to a toilet, where it can be reused for flushing. Such technologies can reduce the amount of drinkable water used and the volume of water going into sewage treatment plants. Figure 9.25
Residential Water Use • Landscape with native plants suited to climate • Use graywater or collected rainwater for irrigation • Fix leaks • Install low flow appliances • Other?
