Chapter 18: Water Supply, Use and Management. Overview Water Water Water Supply - A US Example Water Supply - A US Example Water Use Water Use Water Conservation.

Chapter 18:Chapter 18:

Water Supply, Use and Water Supply, Use and

ManagementManagement

OverviewOverview WaterWater Water Supply - A US ExampleWater Supply - A US Example Water UseWater Use Water ConservationWater Conservation Sustainability and Water ManagementSustainability and Water Management WetlandsWetlands Dams and the EnvironmentDams and the Environment Global Water Shortage Linked to Food Global Water Shortage Linked to Food

SupplySupply

WaterWater

Water’s characteristics:Water’s characteristics: High capacity to absorb and store heatHigh capacity to absorb and store heat Universal solventUniversal solvent High surface tensionHigh surface tension Only compound whose solid form is lighter Only compound whose solid form is lighter

than its liquid formthan its liquid form Permits sunlight penetration water, allowing Permits sunlight penetration water, allowing

photosynthetic organisms to live below the photosynthetic organisms to live below the surfacesurface

A Brief Global PerspectiveA Brief Global Perspective

We are facing a growing global water We are facing a growing global water shortage shortage Linked to the food supplyLinked to the food supply

Global hydrologic cycleGlobal hydrologic cycle Water can be liquid, solid or gasWater can be liquid, solid or gas Transfers water from the atmosphere, to Transfers water from the atmosphere, to

land, to oceans, and back to atmosphereland, to oceans, and back to atmosphere Residence time varies from a few days to Residence time varies from a few days to

thousands of yearsthousands of years

The Hydrologic CycleThe Hydrologic Cycle

A Brief Global PerspectiveA Brief Global Perspective

Where is water globally?Where is water globally? 97% in oceans, 2% in ice, 0.001% in 97% in oceans, 2% in ice, 0.001% in

atmosphereatmosphere 99% of all water on earth is unavailable 99% of all water on earth is unavailable

or unusable (salt) to plants and animalsor unusable (salt) to plants and animals Water is the most use resource on Water is the most use resource on

earthearth Mass of water used 1000x the total Mass of water used 1000x the total

production of mineralsproduction of minerals This is only increasing with greater This is only increasing with greater

industrial production and technologyindustrial production and technology

Groundwater and StreamsGroundwater and Streams Groundwater Groundwater - -

Water located below the water tableWater located below the water table saturated conditionssaturated conditions

Recharge zonesRecharge zones Locations where surface waters move into the Locations where surface waters move into the

groundwatergroundwater Discharge zonesDischarge zones

Locations where water flows or seeps out of Locations where water flows or seeps out of groundwatergroundwater

Vadose zoneVadose zone Area where water seeps through pore spacesArea where water seeps through pore spaces

Groundwater and StreamsGroundwater and Streams

AquiferAquifer Underground zone from which Underground zone from which

groundwater can be obtainedgroundwater can be obtained Cone of DepressionCone of Depression

Forms in water table elevation when Forms in water table elevation when water is pumped from an aquiferwater is pumped from an aquifer

StreamsStreams

Effluent streamEffluent stream Flow is maintained during the dry season by Flow is maintained during the dry season by

seepage into channel from subsurfaceseepage into channel from subsurface Perennial stream - flows all yearPerennial stream - flows all year

Influent streamInfluent stream Entirely above the water table and flows only in Entirely above the water table and flows only in

direct response to precipitationdirect response to precipitation Ephemeral streamEphemeral stream

A stream can have reaches that are both of A stream can have reaches that are both of these, or intermittent at varying times of yearthese, or intermittent at varying times of year

Interactions Between Surface Interactions Between Surface Water and GroundwaterWater and Groundwater

Should be considered part of the Should be considered part of the same resourcesame resource

Nearly all surface water environments Nearly all surface water environments have linkages with ground waterhave linkages with ground water Ex: withdrawal of groundwater can lower Ex: withdrawal of groundwater can lower

stream flow or lake levelsstream flow or lake levels Pollution can spread from one source to Pollution can spread from one source to

the otherthe other

Water Supply: A US ExampleWater Supply: A US Example

Water supply depends on several factors Water supply depends on several factors in the hydrologic cyclein the hydrologic cycle Rates of precipitation, evaporation, Rates of precipitation, evaporation,

transpirationtranspiration Stream flowStream flow Subsurface flowSubsurface flow

Water budgetWater budget Model that balances the inputs, outputs, and Model that balances the inputs, outputs, and

storage of water in a systemstorage of water in a system Precipitation – evaporation = runoffPrecipitation – evaporation = runoff

Water Supply: A US ExampleWater Supply: A US Example

Amount of water vapor passing over Amount of water vapor passing over the US every day ~ 152,000 million the US every day ~ 152,000 million mm33

10% falls as precipitation 10% falls as precipitation 66% of which is evaporated or transpired66% of which is evaporated or transpired Only 34% enters surface or groundwaterOnly 34% enters surface or groundwater

Useful in developing water budgets Useful in developing water budgets for water resources management for water resources management Potential problems can be predicted in Potential problems can be predicted in

areas with:areas with: Low average runoff Low average runoff Low precipitationLow precipitation

Total storage of runoff not possible Total storage of runoff not possible because of evaporative lossesbecause of evaporative losses

Precipitation and Runoff Precipitation and Runoff PatternsPatterns

DroughtsDroughts

Areas with high precipitation and Areas with high precipitation and runoff may suffer from droughtsrunoff may suffer from droughts Large annual and regional variations in Large annual and regional variations in

stream flowstream flow

Groundwater Use and Groundwater Use and ProblemsProblems Half the US population use groundwater as Half the US population use groundwater as

a primary source of drinking watera primary source of drinking water Groundwater accounts for 20% of water Groundwater accounts for 20% of water

used in USused in US In many parts of the US, withdrawal from In many parts of the US, withdrawal from

wells exceeds natural inflowwells exceeds natural inflow OverdraftOverdraft Mining a nonrenewable resourceMining a nonrenewable resource Problems include damage to river basins and Problems include damage to river basins and

land subsidenceland subsidence

Water UseWater Use

Off-stream useOff-stream use Refers to water removed from its source Refers to water removed from its source

for usefor use May be returned to source after useMay be returned to source after use Consumptive use- water is not returned Consumptive use- water is not returned

to its sourceto its source Plant or animals water use (evaporates in Plant or animals water use (evaporates in

the tissue, or is used to make new organs)the tissue, or is used to make new organs) Industrial useIndustrial use

Water UseWater Use

In-stream useIn-stream use Water left in its Water left in its

source for usesource for use Navigation, Navigation,

hydroelectric hydroelectric power, fish and power, fish and wildlife habitats, wildlife habitats, and recreationand recreation

Multiple uses can Multiple uses can create create controversycontroversy

Water UseWater Use

Problem with off-stream useProblem with off-stream use How much water can be removed How much water can be removed

without damaging the stream without damaging the stream ecosystem?ecosystem?

Ex: Aral SeaEx: Aral Sea Diverting water for agriculture caused sea to Diverting water for agriculture caused sea to

dry updry up Surface area of sea reduced 90% in 50 yearsSurface area of sea reduced 90% in 50 years

Aral SeaAral Sea

Climate changesClimate changes Winters colder, summers warmerWinters colder, summers warmer Loss of fishing and decline of tourismLoss of fishing and decline of tourism

Salt content of Salt content of the water has the water has increasedincreased

Dust storms Dust storms from dry salt from dry salt flatsflats

Transport of WaterTransport of Water

Ancient civilizations Ancient civilizations Constructed canals and aqueducts to Constructed canals and aqueducts to

transport water transport water In modern civilization In modern civilization

Water moved from areas of abundant Water moved from areas of abundant rain and snow fall to areas of high usagerain and snow fall to areas of high usage

ExamplesExamples California moves water from north to southCalifornia moves water from north to south New York City has imported water from New York City has imported water from

nearby areas for more than 100 yearsnearby areas for more than 100 years

Some Trends in Water UseSome Trends in Water Use

Withdrawal of surface water far Withdrawal of surface water far exceeds withdrawal of groundwaterexceeds withdrawal of groundwater

Since 1980 use has decreased and Since 1980 use has decreased and leveled offleveled off Suggests improvement in water Suggests improvement in water

management and conservationmanagement and conservation

Some Trends in Water UseSome Trends in Water Use

Trends in freshwater withdrawals by Trends in freshwater withdrawals by water-use categories suggests:water-use categories suggests:

1.1. Major uses of water are for irrigation Major uses of water are for irrigation and the thermoelectric industryand the thermoelectric industry

2.2. Water use for irrigation increased from Water use for irrigation increased from 1950–1980, but decreased and leveled 1950–1980, but decreased and leveled off from 1985–2000 off from 1985–2000

Due to better irrigation efficiency, crop Due to better irrigation efficiency, crop type and higher energy coststype and higher energy costs

Some Trends in Water UseSome Trends in Water Use

3.3. Water use by thermoelectric industry Water use by thermoelectric industry decreased slightly in 1980, and decreased slightly in 1980, and stabilized in 1985.stabilized in 1985.

Due to recirculating water for coolingDue to recirculating water for cooling

4.4. Water for public and rural supplies Water for public and rural supplies continued to increase through the continued to increase through the period from 1950 to 2000period from 1950 to 2000

Presumably related to the increase in Presumably related to the increase in human populationhuman population

Water ConservationWater Conservation

Careful use and protection of water Careful use and protection of water resourcesresources Involves both quantity and quality of waterInvolves both quantity and quality of water Important component of sustainable water Important component of sustainable water

useuse Three componentsThree components

Agricultural UseAgricultural Use Domestic UseDomestic Use Industrial UseIndustrial Use

Agricultural UseAgricultural Use

Agriculture is biggest user of waterAgriculture is biggest user of water Improved irrigation could reduce Improved irrigation could reduce

agricultural withdrawals by 20 to 30%agricultural withdrawals by 20 to 30% Suggestions for conservationSuggestions for conservation

Price agricultural water to encourage Price agricultural water to encourage conservation conservation

Use lined or covered canals that reduce Use lined or covered canals that reduce seepage and evaporationseepage and evaporation

Agricultural UseAgricultural Use

Suggestions for conservation (cont’d)Suggestions for conservation (cont’d) Use computer monitoring and schedule Use computer monitoring and schedule

release of water for maximum efficiencyrelease of water for maximum efficiency Integrate the use of surface water and Integrate the use of surface water and

groundwater to more effectively use the groundwater to more effectively use the total resourcetotal resource

Irrigate at times when evaporation is Irrigate at times when evaporation is minimalminimal

Agricultural UseAgricultural Use

Suggestions for conservation (cont’d)Suggestions for conservation (cont’d) Use improved irrigation systems that Use improved irrigation systems that

more effectively apply water to cropsmore effectively apply water to crops Sprinklers or drip irrigationSprinklers or drip irrigation

Improve the soil to increase infiltration Improve the soil to increase infiltration and minimize runoffand minimize runoff

Encourage the development of crops Encourage the development of crops that require less water or are more salt that require less water or are more salt toleranttolerant

Agriculture in 1990Agriculture in 1990

Agriculture in 2020Agriculture in 2020

Domestic UseDomestic Use

Accounts for about 10% of total Accounts for about 10% of total national water withdrawalsnational water withdrawals But concentrated in urban areasBut concentrated in urban areas May pose major local problemsMay pose major local problems

Domestic UseDomestic Use

Ways to reduce water useWays to reduce water use In semiarid regions, replace lawns In semiarid regions, replace lawns

with decorative gravels and native with decorative gravels and native plantsplants

Use more efficient bathroom fixturesUse more efficient bathroom fixtures Turn off water when not neededTurn off water when not needed Flush the toilet only when necessaryFlush the toilet only when necessary Fix all leaks quicklyFix all leaks quickly

Domestic UseDomestic Use

Ways to reduce water use (cont’d)Ways to reduce water use (cont’d) Purchase efficient dishwashers and Purchase efficient dishwashers and

washing machineswashing machines Take a long bath rather than a long Take a long bath rather than a long

showershower Sweep sidewalks and drivewaysSweep sidewalks and driveways Using gray water to water vegetationUsing gray water to water vegetation Water lawns and plants at cool times to Water lawns and plants at cool times to

reduce evaporationreduce evaporation

Domestic UseDomestic Use

Ways to reduce water use (cont’d)Ways to reduce water use (cont’d) Use drip irrigation and place water-Use drip irrigation and place water-

absorbing mulch around garden plantsabsorbing mulch around garden plants Plant drought-resistant vegetationPlant drought-resistant vegetation Use the water meter to monitor for Use the water meter to monitor for

unobserved leaks unobserved leaks Use reclaimed waterUse reclaimed water

Industry and Manufacturing Industry and Manufacturing UseUse Water conservation measures that Water conservation measures that

can be taken by industrycan be taken by industry Using cooling towers that use little or no Using cooling towers that use little or no

waterwater In-plant water treatment and recyclingIn-plant water treatment and recycling

Sustainability and Water Sustainability and Water ManagementManagement Sustainable water use definitionSustainable water use definition

Use of water resources by people in a Use of water resources by people in a way that allows society to develop and way that allows society to develop and flourish into an indefinite futureflourish into an indefinite future

Use of water without degrading the Use of water without degrading the various components of the hydrologic various components of the hydrologic cycle or the ecological systems that cycle or the ecological systems that depend on itdepend on it

Sustainable Water UseSustainable Water Use

General criteriaGeneral criteria Develop water resources in sufficient Develop water resources in sufficient

volume to maintain human health and well-volume to maintain human health and well-beingbeing

Provide sufficient water resources to Provide sufficient water resources to guarantee the health and maintenance of guarantee the health and maintenance of ecosystemsecosystems

Ensure minimum standards of water quality Ensure minimum standards of water quality for the various users of water resourcesfor the various users of water resources

Sustainable Water UseSustainable Water Use

General criteria (continued)General criteria (continued) Ensure that actions of humans do not Ensure that actions of humans do not

damage or reduce long-term damage or reduce long-term renewability of water resourcesrenewability of water resources

Promote the use of water-efficient Promote the use of water-efficient technology and practicetechnology and practice

Gradually eliminate water pricing Gradually eliminate water pricing policies that subsidize the inefficient use policies that subsidize the inefficient use of waterof water

Groundwater SustainabilityGroundwater Sustainability

Sustainability involves a long term Sustainability involves a long term perspectiveperspective For groundwater even longerFor groundwater even longer

It takes a long time to regenerate It takes a long time to regenerate groundwatergroundwater

Effects of pumping might not be seen Effects of pumping might not be seen immediatelyimmediately

Long-term approach involves balancing Long-term approach involves balancing withdrawal with rechargewithdrawal with recharge

Water ManagementWater Management

Management of water resources is a Management of water resources is a complex issue complex issue Will become more difficult as demand for Will become more difficult as demand for

water increaseswater increases Options for minimizing potential Options for minimizing potential

problemsproblems Alternating water supplies and managing Alternating water supplies and managing

existing supplies betterexisting supplies better Towing icebergsTowing icebergs As price goes up many innovative programs As price goes up many innovative programs

are possibleare possible

Variable-water-source Variable-water-source approachapproach

Master Plan for Water Master Plan for Water ManagementManagement New management philosophy: surface New management philosophy: surface

water and groundwater are both water and groundwater are both subject to natural flux with time subject to natural flux with time In wet yearsIn wet years

Plenty of surface waterPlenty of surface water Near-surface groundwater resources are Near-surface groundwater resources are

replenishedreplenished During dry yearsDuring dry years

Specific plans to supply water on an Specific plans to supply water on an emergency basis must be in place and ready emergency basis must be in place and ready to useto use

Master Plan for Water Master Plan for Water ManagementManagement

Advanced planning may includeAdvanced planning may include Drilling to wells that are presently Drilling to wells that are presently

isolatedisolated Reuse of waste waterReuse of waste water Develop surface water and use Develop surface water and use

groundwater in dry yearsgroundwater in dry years In wet years pump excess surface water In wet years pump excess surface water

underground to recharge groundwaterunderground to recharge groundwater

Water Management and the Water Management and the EnvironmentEnvironment

Often a good deal of controversy Often a good deal of controversy surrounds water developmentsurrounds water development Dams, canals, wetlands modificationDams, canals, wetlands modification Resolution of development involves Resolution of development involves

input from a variety of government and input from a variety of government and public groupspublic groups

Virtual WaterVirtual Water

Virtual water- amount of water Virtual water- amount of water needed to create a product or a cropneeded to create a product or a crop Amount of water in the product or crop Amount of water in the product or crop

itself is much smaller than the amount itself is much smaller than the amount of water it took to create itof water it took to create it

Ex: How much water does it take to Ex: How much water does it take to make a cup of coffee?make a cup of coffee? 40 gallons!40 gallons!

Virtual WaterVirtual Water

Concept of virtual waterConcept of virtual water Promotes efficient use of water from Promotes efficient use of water from

local to global scalelocal to global scale Offers regions greater water securityOffers regions greater water security Helps us to understand relationships Helps us to understand relationships

between water consumption patterns between water consumption patterns and their environmental economic and and their environmental economic and political impactspolitical impacts

WetlandsWetlands

Term for landforms Term for landforms such as salt such as salt marshes, swamps, marshes, swamps, bogs, prairie bogs, prairie potholes, and vernal potholes, and vernal poolspools

Shallow depressions Shallow depressions that seasonally hold that seasonally hold waterwater

Common feature is Common feature is that they are wet at that they are wet at least part of the yearleast part of the year

WetlandsWetlands

Areas that are inundated by water or Areas that are inundated by water or where the land is saturated to a depth of where the land is saturated to a depth of a few cm for at least a few days per yeara few cm for at least a few days per year

Three major components used to Three major components used to determine the presence of wetlands are: determine the presence of wetlands are: HydrologyHydrology Type of vegetationType of vegetation Type of soilType of soil

Natural Service Functions of Natural Service Functions of WetlandsWetlands Freshwater wetlands are a natural sponge Freshwater wetlands are a natural sponge

for water - reducing floodingfor water - reducing flooding Freshwater wetlands can act as areas of Freshwater wetlands can act as areas of

groundwater recharge or dischargegroundwater recharge or discharge Wetlands are one of the primary nursery Wetlands are one of the primary nursery

grounds for fish, shellfish, aquatic birds, grounds for fish, shellfish, aquatic birds, and other animalsand other animals

Wetlands are natural filters that purify Wetlands are natural filters that purify waterwater

Natural Service Functions of Natural Service Functions of WetlandsWetlands Wetlands are often highly productive and Wetlands are often highly productive and

are places where many nutrients and are places where many nutrients and chemicals are naturally cycledchemicals are naturally cycled

Coastal wetlands provide a buffer for Coastal wetlands provide a buffer for inland areas from storms and high wavesinland areas from storms and high waves

Wetlands are an important storage site for Wetlands are an important storage site for organic carbonorganic carbon

Wetlands are aesthetically pleasing to Wetlands are aesthetically pleasing to peoplepeople

WetlandsWetlands

Freshwater wetlands are threatened Freshwater wetlands are threatened in many areasin many areas Over the past 200 years > 50% of all Over the past 200 years > 50% of all

wetlands have disappeared, 90% of wetlands have disappeared, 90% of freshwater wetlandsfreshwater wetlands

Diked, drained or filled Diked, drained or filled San Francisco bay estuary considered San Francisco bay estuary considered

the most modified by human activitythe most modified by human activity

WetlandsWetlands

Mississippi River delta includes major Mississippi River delta includes major coastal wetlandscoastal wetlands Historically maintained by floodingHistorically maintained by flooding Accretion processes counter natural Accretion processes counter natural

subsidencesubsidence If accretion decreases area of open water If accretion decreases area of open water

increases and wetland in reducedincreases and wetland in reduced Levees block sediments and costal Levees block sediments and costal

wetlands are being lostwetlands are being lost

Restoration of WetlandsRestoration of Wetlands

Number of projects have attempted to Number of projects have attempted to restore wetlands- varied successrestore wetlands- varied success Freshwater marshes recovery Freshwater marshes recovery

Linked to availability of water at the siteLinked to availability of water at the site Salt marshes more complexSalt marshes more complex National Environmental Policy Act of National Environmental Policy Act of

19691969 If wetlands destroyed by development must If wetlands destroyed by development must

be replaced elsewherebe replaced elsewhere

Restoration of WetlandsRestoration of Wetlands

Constructing wetlands to clean up Constructing wetlands to clean up agricultural wasteagricultural waste Natural ability to remove excess Natural ability to remove excess

nutrients, break down pollutants, and nutrients, break down pollutants, and cleanse watercleanse water

In Florida, human-made wetlands In Florida, human-made wetlands designed to intercept and hold nutrients designed to intercept and hold nutrients so they don’t damage the Evergladesso they don’t damage the Everglades

Dams and the EnvironmentDams and the Environment

Dams and their accompanying Dams and their accompanying reservoirs generally designed to be reservoirs generally designed to be multifunctional structuresmultifunctional structures Recreational activities Recreational activities Generating electricity Generating electricity Providing flood controlProviding flood control Ensuring a more stable water supplyEnsuring a more stable water supply

Often difficult to reconcile various Often difficult to reconcile various uses at a given siteuses at a given site

Dams and the EnvironmentDams and the Environment

Environmental effects of damsEnvironmental effects of dams Loss of land, cultural resources, and Loss of land, cultural resources, and

biological resources in the reservoir areabiological resources in the reservoir area Larger, dams and reservoirs produce a Larger, dams and reservoirs produce a

potential serious flood hazard should potential serious flood hazard should they failthey fail

Storage behind the dam of sediment Storage behind the dam of sediment that would otherwise move downstream that would otherwise move downstream to coastal areasto coastal areas

Dams and the EnvironmentDams and the Environment

Environmental effects of damsEnvironmental effects of dams Downstream changes in hydrology and Downstream changes in hydrology and

in sediment transport change river in sediment transport change river ecosystemecosystem

Fragmentation of ecosystems above and Fragmentation of ecosystems above and below a dambelow a dam

Restrict movement upstream and Restrict movement upstream and downstream or organic material, downstream or organic material, nutrients and aquatic organismsnutrients and aquatic organisms

Dams and the EnvironmentDams and the Environment

Many people Many people vehemently against vehemently against building new damsbuilding new dams But if present water But if present water

use practices continue use practices continue we will need new damswe will need new dams

Few acceptable sites Few acceptable sites for damsfor dams

Expensive to build and Expensive to build and operate, many people operate, many people don’t want tax dollars don’t want tax dollars spent on subsidized spent on subsidized waterwater Three Gorges Dam in Yangtze R.Three Gorges Dam in Yangtze R.

Removal of DamsRemoval of Dams

Recent dam removals include Recent dam removals include Edwards Dam in Maine Edwards Dam in Maine Marmot Dam in OregonMarmot Dam in Oregon

After removal both river saw return After removal both river saw return of fish as they migrated upstreamof fish as they migrated upstream Large fish runs transport nutrients Large fish runs transport nutrients

upriver from ocean to forest ecosystemsupriver from ocean to forest ecosystems

Removal of DamsRemoval of Dams

Trapped sediment behind dams must be Trapped sediment behind dams must be dealt with in dam removaldealt with in dam removal If released quickly it could damage downstream If released quickly it could damage downstream

ecosystem and fill poolsecosystem and fill pools Slower release minimizes damageSlower release minimizes damage Matilija Dam in Ventura County cost $300,000 to Matilija Dam in Ventura County cost $300,000 to

build but 10 times that to removebuild but 10 times that to remove Removing dams is simple in concept but Removing dams is simple in concept but

involves complex problems relating to involves complex problems relating to sediment and watersediment and water

Global Water Shortage Global Water Shortage Linked to Food SupplyLinked to Food Supply Both surface water and groundwater are Both surface water and groundwater are

being stressed and depletedbeing stressed and depleted Groundwater in the United States, China, India, Groundwater in the United States, China, India,

Pakistan, Mexico, and many other countries is Pakistan, Mexico, and many other countries is being minedbeing mined

Used faster than it is being renewedUsed faster than it is being renewed Large bodies of water (Ex: Aral Sea) are drying Large bodies of water (Ex: Aral Sea) are drying

upup Large rivers, including the Colorado in the US Large rivers, including the Colorado in the US

and the Yellow in China, do not deliver any and the Yellow in China, do not deliver any water to the ocean in some seasons or yearswater to the ocean in some seasons or years

Global Water Shortage Global Water Shortage Linked to Food SupplyLinked to Food Supply Growing concern that there won’t be Growing concern that there won’t be

sufficient water to grow the food to sufficient water to grow the food to feed 8–9 billion people.feed 8–9 billion people. Food shortage linked to water resources Food shortage linked to water resources

a real possibilitya real possibility Water also linked to energy (fuel) Water also linked to energy (fuel)

As energy cost goes up so does cost of foodAs energy cost goes up so does cost of food

Global Water Shortage Global Water Shortage Linked to Food SupplyLinked to Food Supply SolutionSolution

Control human population growthControl human population growth Conserve and sustain water resourcesConserve and sustain water resources Be proactive now before significant food Be proactive now before significant food

shortages developshortages develop