Water Cycle Review
•Also called the hydrologic cycle •The journey water takes as it circulates from the land to the air and back again. •Involves evaporation, condensation, and precipitation. •Repeats as a never-ending cycle Natural Resource •Naturally occurring substances such a mineral, forest, water, and land that are used by humans. Renewable Resource •A resource that can be used repeatedly because it is replaced naturally (cycle). •Water fits both these criteria. Watershed •Basin-like land formation defined by highpoints and divides that descends into lower elevations. •Carries water from the land after rainfall or snow melts. •Drains all the water into a common outlet such as a stream channel, a reservoir, or bay Fresh Water •Very low amounts of dissolved salt – less than 1% •Examples: •Ponds and Lakes •Streams and Rivers •Wetlands •Makes up 3% of Earth’s water resources, including ice caps and glaciers Salt Water •High concentrations of salt •3.5% of the weight of seawater comes from dissolved salt (salinity) •Examples: •Oceans •Seas •Makes up 97% of Earth’s water resources Surface Water •Water on the surface of the planet •Examples: •Ponds and Lakes •Streams and Rivers •Wetlands •Oceans •Replenished by precipitation and groundwater •More prone to pollution than groundwater Groundwater •Water found underground in cracks and spaces in soil, sand, and rock. •Stored in and moves slowly through aquifers •More than 50% of the people in the U.S. get their drinking water from groundwater. •Largest use is irrigating crops •Less prone to pollution Groundwater Vocabulary •Permeable – rock layers or sediments that transmit groundwater freely a.Must include spaces (pores) throughout the rock layer b.Pores must be connected •Impermeable – few or no connected pore spaces, such as clay •Zone of Aeration – region between the earth’s surface and the water table •Water Table – the upper surface of the Zone of Saturation (can move up or down depending on rainfall) •Zone of Saturation – region in the ground in which the pore spaces are filled with water Aquifers •Found underground •Made of gravel, sand, sandstone, or limestone •Water can move through these materials because they have large connected spaces (pores) that make them permeable. •The flow of water depends on the size of the spaces and how well they are connected. Well •An excavation or structure created in the ground by digging, which accesses groundwater in an aquifer. •The well water is drawn by a pump that is raised mechanically or by hand. •How is the well depth determined? What might make a well “go dry?” •Replenished by precipitation Artesian Well •A place in the ground where water flows up to the surface because of natural pressure without being pumped. •Water comes directly from the aquifer or porous rock layer. •Gravity creates the natural pressure. Water Pollution •Contamination of bodies of water, often by human activity, which affects watersheds •Occurs when pollutants are discharged directly or indirectly into the water. •Along with air pollution, water pollution is the second biggest environmental concern. Point Source Pollution When the pollutants come from a single location such as dumping chemicals into a river. Nonpoint Source Pollution When pollutants are introduced into the environment over a large, widespread area such as agricultural runoff. Types of Water Pollution •Surface water •Oil spillage •Chemical •Groundwater •Thermal •Agricultural Surface Water Pollution •Hazardous substances coming into contact with surface water •Dissolves or mixes physically with the water •Examples: Humans dumping trash into the waterways, especially objects that are swept down storm drains. •Also, sewage Oil Pollution •Release of liquid petroleum hydrocarbons (oil) into the water •Especially harmful to marine and other wildlife •Usually localized, but can spread •Examples: oil spills Chemical Water Pollution •Chemicals from industries and farmers that run off into the waterways. •Examples: metals and solvents from industries •Also, chemicals that control weeds, insects, and pests Groundwater Pollution •Pesticides and chemicals wash deep into the ground by rain water •Can get into the aquifers, thus polluting the groundwater •Anything on the surface can eventually work its way down to the groundwater. •Plume – the area of groundwater affected by the contamination •Look at the diagram and observe the amount of contamination in relationship to the point pollution. Thermal Water Pollution •The rise or fall in the temperature of a natural body of water. •Changes the physical properties of water, particularly the amount of dissolved oxygen in the water. •Decreases fish population and increases death to wildlife Agricultural Pollution •Sediments washing off fields are the largest source of agricultural pollution in the U.S. •Sediments increase the cost of treating drinking water and can also clog fish gills, reducing their resistance to disease. Overuse and Waste •Irrigation uses 30% of all freshwater in the U.S. •Swimming pools and water parks •Golf courses •Washing cars •Watering the lawn What other ways do you overuse or waste water where you live? Land Subsidence •Withdrawing groundwater causing the land to sink •Causes flooding problems •Causes a shift in the foundations of buildings, which can lead to their destruction compare fresh and salt water, including examples? identify the differences between surface and groundwater, including examples? draw and label the parts of an aquifer? recall six different types of water pollution? generate ideas for reducing water pollution? Comments are closed.
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Erik E. Mason
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