WATER RESOURCES

Lecture 14

WHY SHOULD YOU CAREABOUT WATER RESOURCES?

Humans and environment depend on water

– Life made primarily of water- Survival without water a few days- Industry and agriculture use large

amounts

Water unevenly distributed on earth

– Too much floods- Too little becomes main focus of life

-Low cost encourages waste

WE ARE MANAGING FRESHWATER POORLY

Access to freshwater a global health issue An average of 9,300 people die each day from lack of access

to safe drinking water

Economic issue Water vital for producing food and energy

National and global security issue

Environmental issue Excessive withdrawal

THE EARTHS WATER SUPPLY

LIQUID WATER COVERS 3/4 SURFACE

– MOST SALTWATER

– AVAILABLE LIQUID FRESHWATER 0.024% OF TOTAL

– SURFACE WATER (LAKES, RIVERS AND STREAMS)

– GROUNDWATER

HYDROLOGIC CYCLE

-MOVEMENT OF WATER IN THE SEAS, LAND, AND AIR

-DISTRIBUTED UNEVENLY

HUMANS ALTER THE HYDROLOGIC CYCLE

-WITHDRAWING AND POLLUTING WATER AND CAUSING CLIMATE CHANGE

GROUNDWATER

ZONE OF SATURATION SPACES IN SOIL BELOW A CERTAIN DEPTH ARE

FILLED WITH WATER

WATER TABLE TOP OF ZONE OF SATURATION

AQUIFERS RECHARGED NATURALLY BY PRECIPITATION OR BY

NEARBY LAKES, RIVERS, AND STREAMS

SURFACE WATER

SURFACE WATER SURFACE RUNOFF

WATERSHED OR DRAINAGE BASIN

WATER USE IS INCREASING

TWO-THIRDS OF SURFACE RUNOFF LOST TO SEASONAL FLOODS

RELIABLE RUNOFF REMAINING ONE-THIRD IS RELIABLE SOURCE OF

FRESHWATER

WORLDWIDE AVERAGES IRRIGATION FOR CROPS AND LIVESTOCK: 70% INDUSTRIAL USE: 20% CITIES AND RESIDENCES: 10%

WATER FOOTPRINT VOLUME OF WATER USED DIRECTLY OR INDIRECTLY

WATER USE IS INCREASING VIRTUAL WATER

WATER USED TO PRODUCE FOOD AND OTHER PRODUCTS

CASE STUDY: FRESHWATER RESOURCES

IN THE UNITED STATES

MORE THAN ENOUGH RENEWABLE FRESHWATER

-UNEVENLY DISTRIBUTED AND POLLUTED

THE COLORADO RIVER BASIN RUNS THROUGH DRY SOUTHWESTERN

U.S.

– 14 MAJOR DAMS

– MOST WATER REMOVED

– ELECTRICITY

– IRRIGATION

– PUBLIC WATER

– 15% OF U.S. FOOD PRODUCTION AND 13% LIVESTOCK

– FLOW GREATLY DECREASED

– SILTATION

FRESHWATER SHORTAGES WILL GROW

MANY OF THE WORLDS MAJOR RIVER SYSTEMS ARE HIGHLY STRESSED NILE, JORDAN, YANGTZE, AND GANGES

MORE THAN 30 COUNTRIES FACE FRESHWATER SCARCITY ESTIMATE: 60 COUNTRIES BY 2050

30% OF THE EARTHS LAND AREA EXPERIENCES SEVERE DROUGHT RESEARCH PREDICTS THIS WILL WORSEN

GROUNDWATER DEPLETION

GROUNDWATER WITHDRAWALS UNSUSTAINABLE IN SOME AREAS BEING PUMPED FROM AQUIFERS IN SOME AREAS FASTER THAN IT IS RENEWED BY

PRECIPITATION

WIDESPREAD DRILLING OF WELLS BY FARMERS ACCELERATED AQUIFER OVERPUMPING WATER TABLES FALLING

IN 2008, SAUDI ARABIA ANNOUNCED THAT

IT HAD DEPLETED ITS MAJOR DEEP AQUIFER

OVERPUMPING OF THE OGALLALA AQUIFER

OGALLALA AQUIFERLARGEST KNOWN AQUIFER

IRRIGATES THE GREAT PLAINS

VERY SLOW RECHARGE

WATER TABLE DROPPING WATER PUMPED 1040 TIMES FASTER

THAN RECHARGE RATE

GOVERNMENT FARM SUBSIDIES RESULT IN FURTHER DEPLETION

BIODIVERSITY THREATENED IN SOME AREAS

OVERPUMPING AQUIFERS CAN HAVE HARMFUL EFFECTS

LIMITS FOOD PRODUCTION AND RAISES PRICES

WIDENS GAP BETWEEN RICH AND POOR

LAND SUBSIDENCE SAN JOAQUIN VALLEY IN CALIFORNIA MEXICO CITY

GROUNDWATER OVERDRAFTS NEAR COASTAL REGIONS CONTAMINATION OF GROUNDWATER WITH

SALTWATER

DEEP AQUIFERS MIGHT BE TAPPED

MAY CONTAIN ENOUGH WATER TO PROVIDE FOR BILLIONS OF PEOPLE FOR CENTURIES

MAJOR CONCERNS NONRENEWABLE LITTLE IS KNOWN ABOUT THE GEOLOGICAL

AND ECOLOGICAL IMPACTS OF PUMPING DEEP AQUIFERS

NO INTERNATIONAL TREATIES GOVERN ACCESS

COSTS OF TAPPING ARE UNKNOWN WATER IS CONTAMINATED

HOW CAN WE INCREASE FRESHWATER SUPPLIES?

LARGE DAM-AND-RESERVOIR SYSTEMS GREATLY EXPANDED WATER SUPPLIES IN SOME

AREAS

DISRUPTED ECOSYSTEMS AND DISPLACED PEOPLE

MAIN GOAL OF A DAM AND RESERVOIR SYSTEM CAPTURE AND STORE RUNOFF RELEASE RUNOFF AS NEEDED FOR:

FLOOD CONTROL GENERATING ELECTRICITY SUPPLYING IRRIGATION WATER RECREATION (RESERVOIRS)

LARGE DAMS PROVIDE BENEFITS AND CREATE PROBLEMS

RESERVOIRS

INCREASE THE RELIABLE RUNOFF AVAILABLE FOR USE (33%)

DISPLACE PEOPLE (40-80MILLION)

IMPAIR ECOLOGICAL SERVICES OF RIVERS (NUTRIENT CYCLING, CLIMATE MODERATION, WASTE TREATMENT, GROUNDWATER RECHARGE, HABITAT)

ENDANGER PLANT AND ANIMAL SPECIES (1 OUT OF 5 SPECIES) FILL UP WITH SEDIMENT WITHIN 50 YEARS GLACIERS FEEDING THE RIVERS ARE MELTING FAST

WATER TRANSFERS

TRANSFERRING WATER FROM ONE PLACE TO ANOTHER HAS GREATLY INCREASED WATER SUPPLIES IN SOME AREAS

-HAS ALSO DISRUPTED ECOSYSTEMS

WATER TRANSFERRED FROM WATER-RICH TO POOR REGIONS- CANALS AND PIPELINES

– BENEFITS WHERE WATER TRANSFERRED

-WATER LOSS THROUGH EVAPORATION AND LEAKS

– ECOSYSTEMS CHANGE BOTH PLACES

– CALIFORNIA WATER PROJECT

– SACRAMENTO RIVER DEGRADED

– POLLUTION PROBLEMS

CASE STUDY: THE ARAL SEA DISASTER

LARGE-SCALE WATER TRANSFERS IN DRY CENTRAL ASIA HAVE LED TO: WETLAND DESTRUCTION

DESERTIFICATION GREATLY INCREASED SALINITY FISH EXTINCTIONS AND DECLINE OF FISHING BLOWING SALT AND DUST DESTROYING WILDLIFE AND CROPS INCREASED GLACIAL MELTING IN THE HIMALAYAS

CASE STUDY: THE ARAL SEA DISASTER

SHRINKAGE OF THE ARAL SEA HAS ALTERED LOCAL CLIMATE

HOT, DRY SUMMERS, COLDER WINTERS, AND A SHORTENED GROWING SEASON

RESTORATION EFFORTS COOPERATION OF NEIGHBORING COUNTRIES MORE EFFICIENT IRRIGATION DIKE CONSTRUCTION RAISED LEVEL OF

NORTHERN SEA BY 2 METERS

SOUTHERN SEA MAY DRY UP WITHIN FEWYEARS

DESALINATING SEAWATER

OCEAN WATER ABUNDANT

– REMOVAL OF SALT = FRESHWATER

– DISTILLATION OR REVERSE OSMOSIS

– CURRENTLY <1% OF FRESHWATER FOR THE WORLD AND U.S.

– PROBLEMS

– VERY EXPENSIVE

– HIGH ENERGY USE

– DISPOSAL OF SALTY WATER

– MOSTLY IN MIDDLE EAST, NORTH AFRICA,

CARIBBEAN, AND MEDITERRANEAN

(18, 400 ACROSS THE WORLD)

CONSERVING WATER

WAYS TO USE FRESHWATER MORE SUSTAINABLY- 66% OF WATER WASTED

– RAISE WATER PRICES

– SHIFT WATER SUBSIDIES

– INCREASE IRRIGATION EFFICIENCY.

– NIGHT IRRIGATION

– SEVERAL CROPS TOGETHER

– MORE WATER-EFFICIENT CROPS

– IMPORT WATER-DEMANDING CROPS

– USE TREATED WASTEWATER

– CONSERVE WATER IN INDUSTRY

– CONSERVE WATER IN HOMES

WHAT WOULD YOU DO?

WAYS TO REDUCE WATER USE

– SHORT SHOWERS

– WASH FULL LAUNDRY LOADS

– DRIP IRRIGATION

– FIX LEAKS

– WATER SAVING DEVICES

– DONT RUN WATER WHEN NOT USING

– REDUCE MEAT AND WATER RICH FOOD CONSUMPTION

– REPLACE LAWNS WITH LOW-WATER PLANTS

– WASH CAR BY HAND