Water Resources & PollutionAP Environmental ScienceMs. E. Rosa

What You Must KnowImportance 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 Resources97.5% Earth’s water in OceansOnly 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 ResourcesEssential-maintains life/ecosystemsRegulates temperature, redistributes heat,

cycles essential nutrientsFreshwater – renewable because hydrologic

cycle only if managed sustainablyIndustrial nations – concerns with quantityDeveloping – quantity & qualityGlobal climate change will worsen disparity

availability/human needs by altering precipitation patterns, melting glaciers, droughts, flooding

Major Types FreshwaterSurface 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

WetlandsVernal pools: seasonal wetlands

have H20 specific time of yearWetlands: 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

GroundwaterBeneath 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

As Aquifers withdrawn, recharge slowly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

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 ProjectsBring surface H20 fields, homes, cities thru

dams, aqueducts, pipes, open-air canalsColorado 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 ProjectsChannelization – 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 ProjectsCosts/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,

PoliticsTensions 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 DepletionReducing 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 DepletionResidential:

◦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 DepletionIncreasing 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 approachesPrivatization of water supplies