Water is Life !

Mean Annual Precipitation

Water TopicsWater Topics•Water cycle

•Goundwater

•Surface water

•Groundwater/surface water interactions

•Pollution of Streams + groundwater

•Agriculture + Open pit mining

1. Water Supply, Renewal, & Use1. Water Supply, Renewal, & Use

Fig. 12–2© Brooks/Cole Publishing Company / ITP

The Atmosphere - Among the smallest water reservoirs

•Contains 0.001% of total water supply.

•Has the most rapid turnover rate.

•Helps cycle fresh water over landmasses.

Rivers, Lakes, and Wetlands

Lakes have 50x more water than all rivers

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Hydrologic cycleFigure 3.2

3-1

Use of Fresh WaterUse of Fresh Water

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United States•41% agriculture•38% power plant cooling

•11% industry•10% public

Some Requirements•800 gallons / lb beef •100,000 gallons / car•1,000 gallons / lb Al

China•87% agriculture•7% industry•6% public

World•70% agriculture

(60%–80% waste)

WATER USE ISSUES TO EXAMINE:

•Groundwater Mining = withdrawal greater than recharge

•Trees = Flood Prevention = slow water movement

•Pollution = point and non-point sources

•Special Problems: Farming, Mining

Surface HydrologySurface Hydrology•precipitation: rain, sleet, hail, & snow

•runoff: movement along surface

•infiltration: movement from surface to groundwater

•evapotranspiration: evaporation of water from leaves

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The area that a stream drains is called its watershed, drainage basin, or catchment area.

Text: Land area that delivers water, sediment, and dissolved substances via small streams to a major stream or river.

HydrologyHydrologywatershed: region from which water drains into a water body

© Brooks/Cole Publishing Company / ITPFig. 12–3

Springs may result from a perched water table

Groundwater Hydrology TermsGroundwater Hydrology Terms

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•water infiltrates to water table

•aquifer: porous, water–saturated layers of soil or rock through which groundwater flows

•unconfined aquifers: zone of infiltration above (unsaturated) & water table below (saturated)

•confined aquifers: bounded above & below by less permeable rock

•groundwater moves from recharge area through the aquifer & out to a discharge area (well, spring, lake, geyser, stream, or ocean)

Look at the size of these PORE SPACES

Factors influencing the storage and movement of groundwater

• Porosity – percentage of total volume of rock or sediment that consists of pore spaces

• Determines how much groundwater can be stored

• Variations can be considerable over short distances

Permeability = the connection of the pore spaces

• Groundwater, after ice, is the 2nd largest reservoir of fresh water– Infiltration - Process of

water percolating through the soil and into fractures and permeable rocks.

• Zone of Aeration - Upper soil layers that hold both air and water.

• Zone of Saturation - Lower soil layers where all spaces are filled with water.

• Water Table is at the top of the Zone of Saturation

Interactions of water with soil.

Formation of a cone of depression in the water table

Aquifer Recharge zones

Recharge zones - areas where surface watersfilter into an aquifer

Wetlands – Play a vital role in hydrologic cycle

Lush plant growth stabilizes soil and retards surface runoff, allowing more aquifer infiltration.

–Disturbance (including urban development) reduces natural water-absorbing capacity

–resulting in floods and erosion in wet periods, and less water flow the rest of the year.

Plants reduce FloodingPlants reduce Flooding

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Trees/plants slow rain runoff by:

1. Leaves absorbing rainwaters

2. Waters drip down canopy, trunks, to roots

3. Roots absorb waters

4. Soil with organic material absorbs water well and expands

5. Water percolates to water table

Human’s can increase flooding by:

•removing vegetation

•overgrazing

•logging

•forest fires

•mining

•destruction of wetlands

•building on floodplains

•urbanization

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Three dimensions of stream structureFigure 3.30

3-15

• Rivers, Lakes and Streams –

• Precipitation that does not evaporate • or infiltrate into the ground

– All eventually toward the sea!• Best measure of water volume carried by a river is

Discharge.

–The amount of water measured as cubic feet per second (CFS).

– http://www.americanwhitewater.org/content/

River_show-gauge-info_reachid_2209_

Gaining and losing streams

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River flow in moist temperate and semiarid climatesFigure 3.32

3-16     Source: Calow and Petts 1992

Water Availability and Use

• Clean, fresh water is requisite for human survival.

• Renewable water supplies consist of surface runoff and infiltration into shallow ground water.

• Picture shows a ditch for irrigation of crops.

• Water rights for such activities have long been a source of tension and conflict.

Water use issues are

complicated by many countries

competing for limited resources

Water collecting in Africa is time consuming

Freshwater Shortages

• About 25% of the world's people lack adequate, clean drinking water and about 50% lack adequate sanitation.

• Water stress is a phrase used to describe countries where water consumption exceeds by >20% the available, renewable water supply

• Widespread water shortages are predicted by 2025.

Aral SeaAral Sea

Fig. 13–14

•once world's 4th largest freshwater lake;

•shrinking & getting saltier since 1960;

•most water diverted for crops;

•pollutants (pesticides, fertilizers, etc.) causing severe health problems;

•ecological problems - 20 of 24 native fish extinct.

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Depleting Groundwater

• Groundwater provides nearly 40% of the fresh water for agricultural and domestic use in the United States.

• In many areas in the U.S., groundwater is being withdrawn from aquifers faster than natural recharge can replace it.

US Groundwater OverdraftsUS Groundwater Overdrafts

Fig. 12–10

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The Ogallala Aquifer (a huge aquifer in the US Central Plains and most agriculture is dependent on it) –

water usage here is the similar to mining for a nonrenewable resource and the water resource is being depleted rapidly.

Ogallawa AquiferOgallawa Aquifer

Fig. 12–11

• largest known aquifer;

•90% withdrawn for irrigation; supplies 30% of irrigation water;

•supports $32 billion agriculture;

•most areas water withdrawn much faster than recharge. © Brooks/Cole Publishing Company / ITP

Irrigation Methods:•Flooding fields•Sprinklers•Drip Irrigation

Saltwater intrusion Groundwater WithdrawalSaltwater intrusion Groundwater Withdrawal

along coastlines where overuse of freshwater reservoirs draws the water table low enough so saltwater intrudes.

Fig. 12–12© Brooks/Cole Publishing Company / ITP

Nearly half of Mexico is arid or semiarid, with scarce waters. At least 92 springs and 2500 km of river have dried in this area.

There are nearly 200 species of freshwater fishes in this region, 120 under some threat, 15 extinct through human impact. As of 1985, an average of 68% of species was eradicated in local fish faunas.

Surface waters have diminished, and intrusion of saline waters and salinization of agricultural wells in Sonora, arsenic to agricultural waters, and threatening metropolitan Torreon.

Finally, salinization of the lower Rio Bravo del Norte has replaced 32 native fish of fresh of slightly brackish water with 54 mainly marine or highly salt-tolerant species, the salinization threatens all uses of water. Some marine fishes invade up to 400 km upstream.

Dried-up Colorado takes toll on giant Mexican fishJune 8, 2008

The Colorado River vanishes before it reaches the Sea of Cortez in all but the wettest years. Companies in California and the southwestern U.S. have diverted its once-vibrant flow to quench their thirst for water and power. The damming of the Colorado

River has choked the natural flow of sediment and nutrients, causing erosion. Similarly, a protective estuary in the Gulf of California no longer exists, leaving few places for young totoaba to find food and hide from predators.

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Tidal level and mangrove distributionsFigure 3.25

3-12

Mangrove wildlife

Mangrove forests are comprised of unique plant species that form the critical interface between terrestrial, estuarine, and near-shore ecosystems in the tropics.

Mangrove species are uniquely adapted to tropical and coasts, and mangrove forests provide at least US $1.6 billion each year in ecosystem services.

Globally, mangrove areas are declining rapidly as they are cleared for coastal development and aquaculture and logged for timber and fuel production.

Along the coasts of Central America, about 40% of mangroves species present are threatened with extinction.

“The move for a temporary ban on logging in Selangor was made to safeguard the remaining green lung in Selangor, state Agriculture, Natural Resources and Entrepreneurial Development committee chairman Yaakob Sapari said.”

Ban on logging necessary as only 30% of forest left in Selangor

Part 5: Water Management and Conservation

• Watershed management• Sound farming and

forestry practices• Wetlands conservation• Domestic conservation • Water reclamation and

recycling• Water rights

Ways to Increase Water Supplies• Conservation – should it be on the list?• Building Dams, Canals and Reservoirs• Seeding Clouds

– Condensation Nuclei• Towing Icebergs

– Cost • Desalination

– Most common methods are distillation and reverse osmosis.

• Three to four times more expensive than most other sources.

Water ConservationWater Conservation•irrigation efficiency

drip irrigation, central–pivot, computer monitoring

•recyclinguse of “gray” water

•repair leaky pipes

•water conservationefficient toilets & shower heads

•xeriscaping© Brooks/Cole Publishing Company / ITP

California Water ProjectCalifornia Water Project

Fig. 12–7 © Brooks/Cole Publishing Company / ITP

California Water Project - California Water Project - The Problem•most rainfall in northern California•most population growth & agriculture in southern California

The Solution•water transferred via dams, pumps, & aqueducts

The Controversy•southern California wants more water for growth

•much of water wasted by inefficient irrigation•north needs water for fisheries & flushing pollutants out of San Francisco Bay

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Hetch Hetchy Valley, 1913, before dam was

built. Looking back towards

yosemite.ca.us

Dams are controversial in terms of environmental costs, justice, price mechanisms and water policy,

sedimentation, evaporative losses, etc.

Domestic Conservation• Estimates suggest we

could save half of current domestic water usage without great sacrifice or serious change in lifestyle.

Largest domestic use is toilet flushing.

• Significant amounts of water can be reclaimed and recycled (purified sewage effluent)