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Water Unit

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Aquifers Porous, water bearing layers of sand, gravel and/or rock below earths surface Reservoirs for groundwater Latin:Aqua = Water Ferre = To bring

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2 Types of Aquifers CONFINED Water is in porous, fractured rock Can be artesian (under pressure) Water is sandwiched between two impermeable layers UNCONFINED Water is in sandy/gravelly soil Impermeable layer (ex: solid rock) is beneath the water, but not above Most common ty pe

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2 factors determine productivity: 1.Porosity The amount of water it can hold 2. Permeability The ability of water to flow through it

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Ogallala! Largest aquifer on earth Beneath 8 states, extending from N. Dakota to Texas Once held more water than all of the freshwater lakes, rivers and streams on earth combined Excessive pumping has left no water in some peripheral places

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Groundwater Depletion Aquifer recharge can take thousands of years Depletion Examples: Cone of Depression Saltwater Intrusion Subsidence / Sinkholes

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Cone of Depression and Saltwater Intrusion

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Subsidence Sinkholes Surface craters caused by collapse of an underground channel

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Rivers Riparian Zone The river and its stream banks

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Watershed All the land drained by a river The area retains rainwater and lessens downstream flooding when vegetated Case Study: Unregulated timber cutting along Yangtze caused 30,000 deaths due to flooding

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How to Improve Watershed Management: Less development along floodplains Retain crop residue on fields Minimize plowing and forest cutting on slopes Buffer zones of vegetation near waterways

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Earths Largest Rivers Discharge rate the amount of water that passes a fixed point over a given amount of time. Amazon Brazil, Peru (175,000 m 3 /sec) Orinoco Venezuela (45,300 m 3 /sec) Yangtze Tibet, China (28,000 m 3 /sec) Mississippi US (18,400 m 3 /sec)

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Case Study: 3 Gorges Dam Largest dam in the world 1.2 million people relocated Fragile ecosystems and rare species indigenous to that area were flooded Reservoir flooded thousands of villages Triggering landslides Dam is constructed above a fault line

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3 Gorges Dam

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Lake Stratification (draw it.)

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Point Source Pollution: When a pollutant is identified as coming from a specific source Plume contaminants that seep from a concentrated mass. Exs: smoke from a chimney, image to the right

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Non-Point Source Pollution Pollution that does not have a specific point of origin Ex: parking lots, residential lawns

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POLLUTION Point-Source Examples: Leaky landfill Leaky septic system Thermal pollution Non-Point Source Examples: Runoff/erosion from farms Parking lots Feedlots Atmospheric deposition

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Atmospheric Deposition Contaminants get into air and are redeposited via rain Normal rain: pH ~ 5.6 Acid Rain: pH