Water Resources & Pollution AP Environmental Science Ms. E. Rosa

What You Must Know Importance of H20 & distribution of fresh H20 resources Major types of freshwater systems Categories of H20 use by humans & associated problems with utilization Effective solutions addresses depletion Main categories water pollutants & effect on quality Main procedures involved drinking H20 & human wastewater treatment

Water’s Importance & Freshwater Distribution Resources 97.5% Earth’s water in Oceans Only 2.5% is freshwater, most tied up in glaziers, icecaps & underground aquifers Only 1% freshwater accessible. Water unevenly distributed, from 470”/year in tropics to zero (Chile’s desert) Humans not evenly distributed, arid lands more heavily populated where fresh is scarce

Water’s Importance & Freshwater Distribution Resources Essential-maintains life/ecosystems Regulates temperature, redistributes heat, cycles essential nutrients Freshwater – renewable because hydrologic cycle only if managed sustainably Industrial nations – concerns with quantity Developing – quantity & quality Global climate change will worsen disparity availability/human needs by altering precipitation patterns, melting glaciers, droughts, flooding

Major Types Freshwater Surface water- freshwater found above ground includes streams, lakes, ponds, rivers, wetlands Watershed – land area drained by river systems ¾ of all H20 in US comes surface used for generating electricity, industrial use, irrigation Bodies of H20 classified productivity:

Bodies of H20 Classification Oligotrophic- lakes/ponds with ↓nutrients & ↑O2 Eutrophic – water bodies ↑nutrients & ↓02 Wetlands: surface H20 systems soil is saturated with water generally featured as shallow standing water with noticeable vegetation Marshes, swamps, bogs Rich and productive

Wetlands Vernal pools: seasonal wetlands have H20 specific time of year Wetlands: valuable habitats wildlife, provide ecosystem services by slowing runoff, reduce flooding, recharge aquifers, filter pollutants Extensive drainage in US has allow only half of all wetlands to remain

Groundwater As Aquifers withdrawn, recharge slowly Water tables: ↑limit of groundwater held in aquifer Average flow 1 m/day When drop, become difficult & expensive to extract Mexico, India, China, Asian & Middle Eastern, tables falling 3-10ft/year Coastal: saltwater intrudes, land subsides creating sinkholes Beneath earth’s surface held in pores of rocks/soil Account ¼ of all H20 in US, supply almost ½ of all drinking H20 Aquifer: underground reservoir found in porous, sponge-like rock, sand, or gravel formations Largest Ogalla Aquifer found under 8 US Great Plains states

Categories of H20: Humans Use & Associated Utilization Problems Agriculture: accounts for 70% Earth’s annual freshwater use Demand for human food has doubled land irrigation last 50 yrs. Most irrigation inefficient, crops use 40% water applied Over-irrigation: Leads waterlogging, salinization of lands, ↓crop production Worldwide- 15-35% H20 withdrawal unsustainable

Categories of H20: Humans Use & Associated Utilization Problems Industry-accounts 20% Earth’s fresh water use Residential- 10% Bottled H20 production- significant ground H20 extraction/depletion problem Multinational corporations(Nestle, Pepsi, Coca) extract groundwater selling for profits, move on leaving community with degraded resource base Bottled H20 ecological impact due to packaging/transportation (fossil fuels) Not safer/healthier than tap

H20 Diversion Projects Bring surface H20 fields, homes, cities thru dams, aqueducts, pipes, open-air canals Colorado River – 13 major dams store H20 in reservoirs Diverted H20 to irrigate crops in desert areas & sustain growth of Los Angeles, San Diego, Phoenix California’s arid Imperial Valley – nation’s largest irrigation district(derived from Colorado River) China: building world’s largest diversion to pipe from Yangtze River to Yellow River

H20 Diversion Projects Channelization – widening, deeping, engineering technique to transport, flood control, & improve drainage of water Causes extensive habitat destruction & fragmentation in many parts of world Govt: protection against floods built dikes/levees for urban/residential areas (long raised mounds of earth) along riverbanks Human development- worsens flooding due to paving, compacting soils speeds runoff, sends intense pulses of H20 into rivers during storm events

H20 Diversion Projects Costs/benefits of damming rivers/streams being re-evaluated in US. Largest US dam on Colorado River(Hoover & Glen Canyon Dam) each hold back reservoir that can be used to energy generation. Habitat alteration is one main negative impact of dam’s construction Some dams are being removed (due Costs) Ecosystems restored,

Politics Tensions may heighten future as depletion of fresh water contineues to lead shortages/resource scarcity Human population grows, climate change continues to alter percipitation

Effective Solutions: Freshwater Depletion Reducing demand focusing on conserving & increasing efficiency of use Agriculture: Efficient irrigation methods Drip irrigation, low-pressure spray, lining canal preventing leaks, Choose crops match land & climate Selective breeding & genetic modification Recycling treated municipal H20 wastewater for irrigation

Effective Solutions: Freshwater Depletion Residential: Install low-flow faucets, showerheads, toilets, washing machines Repairing leaks in pipes, water mains Using gray water (wastewater from showers/sinks) to water lawns, Xeriscaping – using plants that adapt to arid conditions

Effective Solutions : Freshwater Depletion Increasing Supply Desalination – removal of salt from seawater Expensive, requires large fossil fuels, kills aquatic life at intakes, generates concentrated salty waste Reverse Osmosis(microfiltration) and distillation 2 methods Tampa, Florida largest desalinization plant in US -Market-Based approaches Privatization of water supplies