Water

Chapters 15 & 22

Water Wars

Water shortage Growing population Poor irrigation efficiency

Economic competition-

Water Cycle

Surface runoff Reliable runoff Watershed (drainage

basin) Groundwater Zone of aeration Zone of saturation Water table Aquifer Natural recharge

Shortages: Removal Lack of recharge

Water Use

Withdrawal- Consumptive water use-

Ownership

Government Private

Excessive Withdrawal

Unsustainable Limits Increases Needs Causes sinkholes

Saltwater Intrusion

Movement of salt water Unusable

Deep Aquifer Concerns:

Knowledge No international water treaties

Wasted Water

65-70% of world water is wasted Causes: Underpricing- Lack of government subsidies

Reducing Water Used to Remove Waste Use pollution prevention Bans Uses

Floods

+ Fertile soils

+ Ample water for irrigation

+ Rivers for transportation & recreation

+ Flat land suitable for crops, buildings, highways, & railroads

- Removal of water-absorbing vegetation

Increasing Flood Damage

Removal of water-absorbing vegetation Draining wetlands Living on floodplains Pavement & buildings

End of Ch. 15

Water Pollution

Any chemical, biological, or physical change in water quality that has a harmful effect on living organisms or makes water unsuitable for desired uses

Coliform Bacteria Count Dissolved Oxygen

Biological Indicators

Point Source Pollution

Discharge of pollutants Sources:

Easy to identify, monitor, & regulate – due to specific location

Nonpoint Source Pollution

Large or dispersed land areas that discharge pollutants into environment over a large area Acid deposition Runoff from croplands, feedlots for livestock,

logged forests, urban streets, lawns, golf courses, parking lots

Safe Drinking Water

+ 74-95% of people have access to clean drinking water

- 1.4 billion people do NOT

- 9,300 die daily due to infectious diseases spread by contaminated water or lack of water for adequate hygiene

Developing Countries

26% of people do not have access to clean drinking water

Decreased Quality of Surface Water Intense downpours = Massive flooding = Overflow of lagoons & sewer lines = Drought = Warm temperatures =

Limiting Factors

Volume of degradable waste Stream volume Flow rate Temperature pH level

Controlling Stream Pollution in Developed Countries+ Increased number & quality of waste-water

treatment plants

+ Industries are required to reduce or eliminate point-source pollution

- Accidental or deliberate release of toxic, inorganic, & organic chemicals causes fish kills & contaminates drinking water

- Sewage treatment plants malfunction

- Nonpoint runoff of pesticides & excess plant nutrients from cropland & animal feedlots

Controlling Stream Pollution in Developing Countries- Discharge of untreated sewage & industrial

waste

- Only 10% of Chinese city sewage is treated

Diluting Lake Pollution

Less effective Stratified layers with little vertical mixing Little flow – water is replaced every 1-100

years (unlike days to weeks for streams)

Eutrophication

Physical, chemical, & biological changes that take place after receiving inputs of plant nutrients (nitrates & phosphates) from natural erosion & runoff

Cultural- Prevention- Cleanup-

Examples- Lake Washington & the Great Lakes

Ocean Pollution

Coastal areas- dumping of sewage & industrial waste, agricultural waste, algal blooms, oxygen-depleted zones (excessive fertilizers & animal wastes)

40% of world population lives with 100km (62mi) of coast

From rivers- Chesapeake Bay

ICM-

Types of Ocean Pollution

Dredge spoils- Sewage sludge-

Reducing Nonpoint Source Pollution

Prevent soil erosion by keeping cropland covered with vegetation

Use slow-release fertilizer Apply pesticides only when needed Use buffer zone around animal feedlots,

animal waste sites, & cultivated fields Use biological controls

Legislature

Clean Water Act- Water Quality Act-

Septic Tanks

Underground tank for treating wastewater from a home in rural & suburban areas

Bacteria decomposes organic waste Sludge settles to bottom Effluent flows out of tank into ground

Primary Sewage Treatment

Mechanical sewage treatment where large solids are filtered out by screens & suspended solids settle out as sludge in sedimentation tank

Secondary Sewage Treatment

2nd step- aerobic bacteria decomposes 90% of degradable, oxygen-demanding organic wastes

Sewage & bacteria is brought together in trickling filters or in activated sludge process

Householdwastewater

Perforated pipe

Distribution box (optional)

Septic tank with manhole (for cleanout)

Drainfield Vent pipe

Nonperforated pipe

Gravel orcrushedstone

Raw sewagefrom sewers

Bar screenGritchamber Settling tank Aeration tank Settling tank

Chlorinedisinfection tank

Sludge

Sludge digester

Activated sludge

Air pump

(kills bacteria)

To river, lake,or ocean

Sludge drying bed

Disposed of in landfill orocean or applied to cropland,pasture, or rangeland

Primary Secondary

Wetlands

Sewage goes into sedimentation tanks (solids settle out as sludge)

Liquid is pumped into oxidation ponds where bacteria breaks down remaining wastes

Water released 1 month later into artificial marsh (plants & bacteria carry out further filtration & cleansing)

Wastewater Garden

Small, low-tech inexpensive artificial wetland Removes 99.9% of fecal coliform bacteria Removes 80% of nitrates & phosphates from

incoming sewage

(1) Raw sewage drains by gravity into the first pool and flows through a long perforated PVC pipe into a bed of limestone gravel.

(3) Wastewater flows through another perforated pipe into a second pool, where the same process is repeated.

(2) Microbes in the limestone gravel break down the sewage into chemicals that can be absorbed by the plant roots, and the gravel absorbs phosphorus.

(4) Treated water flowing from the second pool is nearly free of bacteria and plant nutrients. Treated water can be recycled for irrigation and flushing toilets.

45 centimeterlayer of limestonegravel coated with

decomposing bacteriaFirst concrete pool Second concrete pool

Sewage

Wetland typeplants

Wetland typeplants

Treatedwater

Figure 22-18 Page 513

Water Purification

Stored in reservoir for several days (increases DO level & suspended matter settles)

Water is pumped to purification plant for filtration & chlorination

Vulnerability to Terrorist Attacks

Fear of added chemicals or biological agents Hard to protect due to large numbers of

reservoirs, vast network of purification plants & distribution systems, & accessibility of water systems through fire hydrants & service connections

Purification in Developing Countries

Exposing water in clear plastic bottle to intense sunlight (heat & UV will kill infectious microbes in 3 hrs)

Strips of cloth for filtering cholera-producing bacteria

Add small amount of chlorine-disinfectant solution to plastic or clay storage containers with narrow mouth, cap, & spigot