Water Resources. n Hydrosphere: All the water at or near the surface of the earth n Amount of water essentially constant and moves between different reservoirs.

Water ResourcesWater Resources

Hydrosphere:Hydrosphere: All the water at or All the water at or near the surface of the earthnear the surface of the earth

Amount of water essentially Amount of water essentially constant and moves between constant and moves between different reservoirsdifferent reservoirs

100 million billion gallons move 100 million billion gallons move through Hydrologic Cyclethrough Hydrologic Cycle

Oceans account for ~96%, Fresh Oceans account for ~96%, Fresh water lakes and streams for only water lakes and streams for only 0.016% of all water0.016% of all water

Hydrologic CycleHydrologic Cycle

Distribution of WaterDistribution of Water

Thousands of km3/yr

-

- - +

Hydrologic CycleHydrologic Cycle

Ground waterGround water

22% of all fresh water occur 22% of all fresh water occur undergroundunderground

Aquifer: Underground formation that Aquifer: Underground formation that holds and yields water holds and yields water

A good aquifer needs to be both A good aquifer needs to be both porous and permeableporous and permeable

Porosity and PermeabilityPorosity and Permeability

Porosity:Porosity: Proportion of void space: pore Proportion of void space: pore space, cracks, vesiclesspace, cracks, vesicles• Gravel : 25-45% (1K - 10K), Clay: 45-55%(<.01)Gravel : 25-45% (1K - 10K), Clay: 45-55%(<.01)• sandstone: 5-30% (0.3 - 3), Granite: <1 to 5%(.003 sandstone: 5-30% (0.3 - 3), Granite: <1 to 5%(.003

to .00003)to .00003)• higher porosity in well rounded, equigranular, coarse higher porosity in well rounded, equigranular, coarse

grained rocksgrained rocks

Permeability:Permeability: Measure of how readily fluid Measure of how readily fluid passes through a materialpasses through a material• Depends on the size of the pores and how well Depends on the size of the pores and how well

they are interconnectedthey are interconnected• Clay has high porosity but low permeabiltyClay has high porosity but low permeabilty

Less porosity

porosity permeability

Clay 45-55% <0.01 m/day

sand 30-52% 0.01 - 10

gravel 25 - 45% 1000 to 10,000

Subsurface Subsurface WaterWater

Zone of Aeration or Zone of Aeration or Vadose Zone or Vadose Zone or Unsaturated Zone:Unsaturated Zone: Overlies Phreatic Overlies Phreatic Zone. Pore spaces Zone. Pore spaces partly filled with partly filled with water. Contains soil water. Contains soil moisture.moisture.

Saturated Zone

Zone of Saturation or Phreatic Zone:Zone of Saturation or Phreatic Zone: saturated zone overlying impermeable bed saturated zone overlying impermeable bed rock. Water fills all the available pore spacesrock. Water fills all the available pore spacesWater Table:Water Table: top of the zone of saturation top of the zone of saturation where not confined by impermeable rockwhere not confined by impermeable rock

Water table follows the topography but more gentlyWater table follows the topography but more gently Intersection of water table and ground surface produces Intersection of water table and ground surface produces

lakes, streams, spring, wetlands…lakes, streams, spring, wetlands… Ground water flows from higher elevation to lower, from Ground water flows from higher elevation to lower, from

areas of lower use to higher use, from wet areas to dry areas of lower use to higher use, from wet areas to dry areas.areas.

Darcy’s lawDarcy’s law

Hydraulic Gradient: Slope of the Hydraulic Gradient: Slope of the ground water tableground water table

Rate of flow is proportional to the Rate of flow is proportional to the hydraulic gradienthydraulic gradient

AquiferAquifer

Recharge:Recharge: Process of replenishment of Ground Process of replenishment of Ground Water by infiltration, migration and percolationWater by infiltration, migration and percolation

Aquifer:Aquifer: A rock that holds enough water and A rock that holds enough water and transmits it rapidly. Porous and Permeable. transmits it rapidly. Porous and Permeable. Sandstone and Coarse Clastic Sedimentary Sandstone and Coarse Clastic Sedimentary rocks make good aquifersrocks make good aquifers

Aquitard and Aquiclude:Aquitard and Aquiclude: Rocks of low and very Rocks of low and very low permeability e.g., shale, slate low permeability e.g., shale, slate

Perched water table:Perched water table: Local aquifer in Vadose Local aquifer in Vadose ZoneZone

ConfinedConfined and Unconfined Aquiferand Unconfined Aquifer

Unconfined AquiferUnconfined Aquifer: open to : open to atmosphere e.g., overlain by permeable atmosphere e.g., overlain by permeable rocks and soilsrocks and soils

Confined aquifer:Confined aquifer: sandwiched between sandwiched between aquitardsaquitards• Artesian System:Artesian System: Water rises above the Water rises above the

level in aquifer because of hydrostatic level in aquifer because of hydrostatic pressurepressure

Potentiometric surface:Potentiometric surface: Height to which Height to which water pressure would raise the water.water pressure would raise the water.

Artesian System: Water rises above the level in aquifer because of hydrostatic pressure

Potentiometric surface: Height to which

water pressure would raise the water.

Lowering of Water Table Cone of depression: Circular lowering of water

immediately around a well

Consequences of Ground Water Withdrawal

Consequences of Ground Water Consequences of Ground Water WithdrawalWithdrawal

–overlapping cones of depression causes overlapping cones of depression causes lowering of regional water tablelowering of regional water table–Water mining: rate of recharge too slow for Water mining: rate of recharge too slow for replenishment in human life timereplenishment in human life time

Compaction and Subsurface subsidence

Consequences of Ground Water Consequences of Ground Water Withdrawal….Withdrawal….

Compaction and Subsurface Compaction and Subsurface subsidencesubsidence• Building damage, collapseBuilding damage, collapse• flooding and coastal erosion flooding and coastal erosion

e.g., Venice, e.g., Venice, Galveston/Houston (80 sq km Galveston/Houston (80 sq km permanently flooded), San permanently flooded), San Joaquin Valley (9m Joaquin Valley (9m subsidence)subsidence)

• Pumping in of water no Pumping in of water no solutionsolution

Land subsidence in Land subsidence in San Joaquin Valley , San Joaquin Valley , CaliforniaCalifornia

The High Plains AquiferThe High Plains Aquifer The High Plains is a 174,000-square-mile area of flat to The High Plains is a 174,000-square-mile area of flat to

gently rolling terrain that includes parts of eight States gently rolling terrain that includes parts of eight States from South Dakota to Texas. from South Dakota to Texas.

moderate precipitation but in general has a low natural-moderate precipitation but in general has a low natural-recharge rate to the ground-water system.recharge rate to the ground-water system.

Unconsolidated alluvial deposits that form a water-table Unconsolidated alluvial deposits that form a water-table aquifer called the High Plains aquifer underlie the aquifer called the High Plains aquifer underlie the region. region.

Since early 1800s, irrigation water pumped from the Since early 1800s, irrigation water pumped from the aquifer has made the High Plains one of the Nation’s aquifer has made the High Plains one of the Nation’s

most important agricultural areasmost important agricultural areas.. the intense use of ground water for irrigation has the intense use of ground water for irrigation has

caused upto 100m decline in water-level in parts of caused upto 100m decline in water-level in parts of Kansas, New Mexico, Oklahoma, and Texas.Kansas, New Mexico, Oklahoma, and Texas.

Changes in ground-water levels in the High Plains aquifer from before ground-water development to 1997. (V.L. McGuire, U.S. Geological Survey, written commun., 1998.)

The Gulf Coastal Plain aquifer system underlie about The Gulf Coastal Plain aquifer system underlie about 290,000 square miles extending from Texas to 290,000 square miles extending from Texas to westernmost Florida, including offshore areas to the edge westernmost Florida, including offshore areas to the edge of the Continental Shelf.of the Continental Shelf.

Water withdrawals from the aquifer system have caused Water withdrawals from the aquifer system have caused • lowering of hydraulic heads at and near pumping lowering of hydraulic heads at and near pumping

centers; centers; • reduced discharges to streams, lakes, and wetlands; reduced discharges to streams, lakes, and wetlands; • induced movement of saltwater into parts of aquifers induced movement of saltwater into parts of aquifers

that previously contained freshwater; that previously contained freshwater; • and caused land subsidence in some areas as a result and caused land subsidence in some areas as a result

of the compaction of interbedded clays within aquifers. of the compaction of interbedded clays within aquifers.

The Gulf Coastal Plain Aquifer System

Land subsidence in HoustonLand subsidence in Houston

Flooding in coastal Galveston because of subsidence

Salt water incursion in caostal aquifer

Saltwater Saltwater IntrusionIntrusion

–upconing below cone of upconing below cone of depressiondepression

–Aquifer below Brooklyn, NY Aquifer below Brooklyn, NY destroyeddestroyed

–Serious problem in Gulf Coast Serious problem in Gulf Coast and Californiaand California

Extent of Extent of salt water salt water

incursion in incursion in Miami-Miami-DadeDadeSalt water intrusion in

Miami-Dade

SinkholesSinkholes• forms in areas with abundant water and forms in areas with abundant water and

soluble bedrock (gypsum or limestone)soluble bedrock (gypsum or limestone)• collapse follows ground water collapse follows ground water

withdrawalwithdrawal

Dripstones in a cavernDripstones in a cavern

Stalagmites

Stalagtites

Urbanisation and ground waterUrbanisation and ground water

Loss of RechargeLoss of Recharge• Impermeable cover retards rechargeImpermeable cover retards recharge• Filling of wetlands kills recharge areaFilling of wetlands kills recharge area

Well planned holding pond can help Well planned holding pond can help in recharging ground waterin recharging ground water

Water QualityWater Quality

Most freshwater contain dissolved substancesMost freshwater contain dissolved substances concentrations are described in ppm or ppbconcentrations are described in ppm or ppb TDS=Total Dissolved SolidsTDS=Total Dissolved Solids

• 500 to 1000 ppm for drinking water500 to 1000 ppm for drinking water• 2000 ppm for livestock2000 ppm for livestock• some solids (e.g., Iron, Sulfur) more harmful some solids (e.g., Iron, Sulfur) more harmful

than others (e.g. calcium) than others (e.g. calcium) • synthetic chemicals can be toxic at ppb levelsynthetic chemicals can be toxic at ppb level

Radioactive elements pose special hazardRadioactive elements pose special hazard• Uranium, Radium, RadonUranium, Radium, Radon

Hard waterHard water

Hard Water: Hard Water: • Common in limestone countryCommon in limestone country• contains dissolved Ca and Mg; contains dissolved Ca and Mg;

problematic if >100 ppmproblematic if >100 ppm• problem with soapproblem with soap• leaves deposits in plumbing and in leaves deposits in plumbing and in

appliancesappliances• can be cured with water softener can be cured with water softener

typically ion exchange through zeolitestypically ion exchange through zeolites

Water Use in USWater Use in US

4200 billion gallons of precipitation4200 billion gallons of precipitation 2750 billion gallons lost by 2750 billion gallons lost by

evaporationevaporation 1400 billion gallons available for 1400 billion gallons available for

consumptionconsumption Biological need : 1 gal/person/dayBiological need : 1 gal/person/day US consumption: 1800 gal/person/day US consumption: 1800 gal/person/day

= 400 billion gallons per day for the entire US= 400 billion gallons per day for the entire US

Offstream Use: water diverted from Offstream Use: water diverted from source e.g.,for irrigation or thermal source e.g.,for irrigation or thermal power generationpower generation• Consumptive: water used up Consumptive: water used up

For farming, drinking or lost by evaporationFor farming, drinking or lost by evaporation

Instream: water returns to flow: e.g., Instream: water returns to flow: e.g., for hydroelectric power generationfor hydroelectric power generation

Water Use …contdWater Use …contd

Main Uses:Main Uses:• Thermoelectric PowerThermoelectric Power

Surface: Ground water = 67:33Surface: Ground water = 67:33 Consumed 2%, Return Flow 98%Consumed 2%, Return Flow 98%

• IrrigationIrrigation Surface: Ground water = 63:33Surface: Ground water = 63:33 Consumed 56%, Loss 20%, Return Flow 24%Consumed 56%, Loss 20%, Return Flow 24%

• IndustrialIndustrial Surface 67% (saline 12%), Ground water 15% (1% saline), Surface 67% (saline 12%), Ground water 15% (1% saline),

Public Supply 19%Public Supply 19% Consumption 15%, Return Flow 85%Consumption 15%, Return Flow 85%

• DomesticDomestic Public Supply 86%, Ground Water 13%, Surface 1%Public Supply 86%, Ground Water 13%, Surface 1% Consumption 23%, Return Flow 77%Consumption 23%, Return Flow 77%

Irrigation and Ground waterIrrigation and Ground water

Thus, irrigation is the major Thus, irrigation is the major consumer of ground waterconsumer of ground water

Western states are the major Western states are the major drawers of ground water causing drawers of ground water causing serious environmental problemsserious environmental problems

Most of the precipitation is in the eastern states but…

Most of the water withdrawal is in the western states (see also the next slide)

•Total withdrawal increased from 1950 to 1980 and has held steady since then although population has increased by 16%

•Withdrawal for thermoelectric power generation 190,000 Mgal/day: largest of any other category

•Higher water price, more public awareness, conservation, better farming and industrial techniques will keep water demand in check

Water RightsWater Rights

Riparian Rights (Eastern USA):Riparian Rights (Eastern USA):• Every landowner can make reasonable use of Every landowner can make reasonable use of

lake or stream or water flowing through or lake or stream or water flowing through or bordering his propertybordering his property

• Municipalities have the right of eminent Municipalities have the right of eminent domain: at times of scarcity, cities get their domain: at times of scarcity, cities get their requirement firstrequirement first

• Sale of riparian rights allowed in some statesSale of riparian rights allowed in some states• Practical in regions of plentiful waterPractical in regions of plentiful water

Law of Prior AppropiationLaw of Prior Appropiation

• First come, first servedFirst come, first served• Settlers can lay claim to certain amount of Settlers can lay claim to certain amount of

water which will be honored for perpetuitywater which will be honored for perpetuity• The oldest claim are honored first and any left The oldest claim are honored first and any left

over goes to the next claimant and so on..over goes to the next claimant and so on..• Los Angeles bought up water rights in 1900 Los Angeles bought up water rights in 1900

from areas far and wide, some even from from areas far and wide, some even from Arizona. Now people in those areas are very Arizona. Now people in those areas are very unhappy about the arrangementunhappy about the arrangement

Colorado River basin

The Colorado River flows through Utah to Lake Powell, thence through the northwest corner of Arizona to Lake Mead. From Hoover Dam it flows southward to Mexico forming the border between Nevada, California and Arizona, and yielding major diversions to central Arizona and southern California. The river is the lifeblood of the southwestern US and its development and management have been the focus of attention by the member states for more than a century. Waters of the Colorado River System have been apportioned by a treaty with Mexico, compacts, and a Supreme Court decree to the seven basin states.

Story of Colorado River

Colorado River CompactColorado River Compact The Colorado River Compact of 1922 divided the use of The Colorado River Compact of 1922 divided the use of

waters of the Colorado River System between the Upper and waters of the Colorado River System between the Upper and Lower Colorado River Basin. Lower Colorado River Basin.

It apportioned in perpetuity to the Upper and Lower Basin, It apportioned in perpetuity to the Upper and Lower Basin, respectively, the beneficial consumptive use of 7.5 million respectively, the beneficial consumptive use of 7.5 million acre feet (maf) of water per annum. acre feet (maf) of water per annum.

It also provided that the Upper Basin will not cause the flow It also provided that the Upper Basin will not cause the flow of the river at Lee Ferry to be depleted below an aggregate of the river at Lee Ferry to be depleted below an aggregate of 75 maf for any period of ten consecutive years. of 75 maf for any period of ten consecutive years.

The Mexican Treaty of 1944 allotted to Mexico a guaranteed The Mexican Treaty of 1944 allotted to Mexico a guaranteed annual quantity of 1.5 maf. These amounts, when combined, annual quantity of 1.5 maf. These amounts, when combined, exceed the river's long-term average annual flow.exceed the river's long-term average annual flow.

These apportions were decided during a particularly wet These apportions were decided during a particularly wet climatic period. At present, the flow in Colorado does not add climatic period. At present, the flow in Colorado does not add up to all the apportionmentsup to all the apportionments

Within Colorado water allocations are based on the Doctrine of Prior Appropriation or the First-in-Time, First-in-Right Doctrine. This doctrine is found in most arid states because when there is too little water to satisfy all users, sharing of the remaining water would be of little value to any user. But a large part of the Colorado river water is diverted to Los Angeles on the basis of this doctrine

ConservationConservation

Shift water-hungry crops to regions Shift water-hungry crops to regions with more rainfallwith more rainfall

Use drip irrigation to reduce Use drip irrigation to reduce evaporation lossevaporation loss

Use pipes to reduce transport lossUse pipes to reduce transport loss Water lawns in morning and evening Water lawns in morning and evening

or opt for no lawnor opt for no lawn Direct storm water in recharge basinsDirect storm water in recharge basins

Interbasinal transferInterbasinal transfer

Transfer water from water-surplus Transfer water from water-surplus regions to water-deficient regionsregions to water-deficient regions• California : Los Angeles aqueduct moves 150 California : Los Angeles aqueduct moves 150

million gallons/ day from east of Sierra million gallons/ day from east of Sierra Nevada to LANevada to LA

• New York: Water supply to NYC from Finger New York: Water supply to NYC from Finger Lakes regionLakes region

• political problemspolitical problems DesalinationDesalination

• Filtration, distillationFiltration, distillation• Expensive, limitedExpensive, limited