Watershed: an area or ridge of land that separates waters flowing to different rivers, basins, or seas. It is the interdependent web of living

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1 Watershed: an area or ridge of land that separates waters flowing to different rivers, basins, or seas. It is the interdependent web of living organisms that inhabit a geographic area and depend on it for clean soil, air and water. Everything we do, from mountaintop to marsh, affects the health of local water, soil, air, wildlife. "that area of land, a bounded hydrologic system, within which all living things are inextricably linked by their common water course and where, as humans settled, simple logic demanded that they become part of a community."

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3 The idea that the watershed is on a mountain, and the water reaches the top of the mountain through the water cycle, and comes down the mountain through the rivers collecting at the bottom in a pool

4 A watershed is an area which acts as a funnel, collecting water and shunting it into the ocean or into inland lakes and seas. Watersheds are also sometimes called catchment areas or drainage basins, and they are a very important part of the world's ecology. Because they cross regional and national boundaries, watershed management can be extremely challenging, especially when neighboring nations have differing views about the best way to manage the natural environment.

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6 Surface Water: Water flowing on the earth s surface Surface water is water that collects on the surface of the ground. The collection of surface water can create for example; oceans, lakes, reservoirs, and rivers. A lake is where runoff surface water has accumulated in a low spot on earth s surface. Lake water isn't trapped in one area. The water entering a lake comes in faster than it can escape. A reservoir is a manmade lake that is created when a dam is built on a river. The river water backs up behind the dam which creates the reservoir. One reservoir in westchester county is the Kensico reservoir. This reservoir receives most of its water from the City's west-of-hudson reservoirs through the Catskill and Delaware aqueducts. This reservoir sits through some town such as Armonk, Valhalla, Harrison. It supplies about 18 million gallons daily to the people of these towns. Most reservoirs have an infiltration system which uses chemicals such as fluoride to treat the water to make is safe for people to drink. Most reservoirs use a purification system which use a reverse osmosis system.

7 Rivers: -Most of the water you see flowing in rivers comes from precipitation runoff from the land surface alongside the river -A river forms from water moving from a higher altitude to a lower altitude, all due to gravity. -When rain falls on the land, it either seeps into the ground or becomes runoff, which flows downhill into rivers and lakes, on its journey towards the seas. -Some small creeks flow downhill and merge to form larger streams and rivers -Eventually end up flowing into the oceans (ultimate goal) -Essential not only to humans, but to all life on earth -Plants and animals grow and congregate around rivers simply because water is so essential to all life -A lot of cities were built around rivers -For humans, rivers are diverted for flood control, irrigation, power generation, municipal uses, and even waste disposal.

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10 Oceans: - It is estimated that about 96.5 percent of the world s water supply is stored in oceans -The water in the oceans is saltwater (saline) (salt is dissolved in the water) -Water is always in movement -Ocean covers 70% of the earth s surface -if the salt in the ocean could be removed and spread evenly over the Earth's land surface it would form a layer more than 500 feet (166 meters) thick, about the height of a 40-story office building

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13 A lake is where runoff surface water has accumulated in a low spot on earth s surface. Lake water isn't trapped in one area. The water entering a lake comes in faster than it can escape. Lakes are home to many different organisms such as plants, insects, amphibians, mammals. Lakes can become polluted from fertilizers and pesticides, raw sewage gets dumped into waterways which makes it into lakes, sediment from landscapes can wash into lakes.

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15 Reservoirs: The collection of surface water can create for example; oceans, lakes, reservoirs, and rivers. A reservoir is a manmade lake that is created when a dam is built on a river. The Kensico reservoir is in westchester going through towns such as Armonk, Valhalla, Harrison. It supplies about 18 million gallons daily to the people of these towns. This reservoir receives most of its water from the City's westof-hudson reservoirs through the Catskill and Delaware aqueducts. Most reservoirs have an infiltration system which uses chemicals such as fluoride to treat the water to make is safe for people to drink. Most reservoirs use a purification system which use a reverse osmosis system.

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17 Underground River Some areas of the crust are so absorbent that water gathers deep underground. If the crust s material is more easily eroded underground, the water will begin to flow under the surface. A Underground River is a stream running under the earth. A famous underground river is Puerto Princesa Underground River Knowing where groundwater comes from provides a better perspective of how groundwater can become contaminated from land uses. Because groundwater originates as precipitation sinking down from the land surface, downward-infiltrating water must pass through whatever is at or below the surface. At any given location, groundwater tends to be harder and more saline than surface water, but this is by no means a universal rule. (2)

18 It is also generally the case that groundwater becomes more saline with increasing depth.(1) Engineers must consider groundwater when planning almost any kind of structure, either above or below the ground. Ignoring the effect of groundwater on slope stability can be both costly and dangerous. The fluid pressures exerted by groundwater, for example, play an important role in the occurrence of earthquakes.(3) The movement of water through underground geologic formations controls the migration and the accumulation of petroleum and the formation of some ore deposits.(3) Groundwater moves so slowly that problems take a long time to appear. In result of this and because of how expensive it is to clean up a contaminated aquifer it is preferable to prevent contamination from happening in the first place.

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21 Aquifers: An aquifer is an underground layer of permeable rock and solid material such as gravel, sand, or silt which groundwater can be taken out using a water well. Aquifers can be contaminated by harmful chemicals that can seep down through the rock and soil into aquifers Aquifers can recharge by precipitation into the porous rock A confined aquifers are when the porous rock become tilted and both of the less porous rock are above and below the porous layer. There is a possibility of a layer with less porous rock. The result of this is when the well is drilled, the pressure makes the water move up into the well without any aid of a pump which is an artesian well Water Table: The level below which the ground is filled with water The movement of water depends on how permeable the rock is Unconfined Aquifer: Also known as the Water table well. An aquifer which has the water table as the upper boundary. Occurs near the ground surface. Artesian aquifers is a confined aquifer that has groundwater under positive pressure

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25 Water Treatment: screening First unit operation used at wastewater treatment plants removes objects such as rags, paper, plastics, and metals to prevent damage and clogging of downstream equipment, piping, and appurtenances. Modern water waste treatment plants use coarse screens and fine screens to filter out large and small objects Coarse screens remove large solids, rags, and debris from wastewater, and typically have openings of 6 mm (0.25 in) or larger. Fine screens are typically used to remove material that may create operation and maintenance problems in downstream processes, particularly in systems that lack primary treatment. Typical opening sizes for fine screens are 1.5 to 6 mm typically at the bottom of the resevoir and

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28 Chlorination Chlorination is one of many methods that can be used to disinfect water. It is a chemical disinfection method that uses various types of chlorine or chlorinecontaining substances for the oxidation and disinfection of what will be the potable water source.

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30 Ozonation Today, it is the most commonly used disinfection process in Europe. Ozone is used in the same manner as chlorine. The major difference is that ozone is unstable so cannot be produced and transported to the point of use. For water treatment, Ozone can injected or diffused into the water supply stream. Ozone is extremely active as a disinfectant. A wider range of organisms is killed by ozonation than by chlorination. It also achieves excellent removal of taste and odors.

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32 Fluoridation Water fluoridation is the controlled addition of fluoride to a public water supply. It is used to prevent tooth decay and prevent cavities. This process has helped strengthen teeth and reduce tooth decay by 25 % The United States has been using fluoridation for 70 years The three additives are Fluorosilicic acid Sodium fluorosilicate Sodium fluoride These additives do not affect taste, color, or smell of the water The maximum amount of fluoride in the water can be 0.7 milligrams per liter

33 Reverse osmosis By applying pressure to the water solution of higher concentration (the incoming water), the flow of liquid is reversed. Under these conditions, the membrane still rejects the contaminants, but allows the fresh, cleansed water to pass through. The purified water is then stored in a holding tank and the contaminants are flushed away. This process is typically used to remove sodium from the water, but will also remove arsenic, uranium, nitrates, lead and range of other potential contaminants. process responsible for removing salt from water. In Perth, Australia (notably dry and arid, yet surrounded by sea), nearly 17 percent of the area's drinking water is desalinated sea water that comes from a reverse osmosis plant

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