CALIFORNIA’S WATER WAR: PART IIBalancing Agricultural and Domestic Water Demands

Sharon Liu

Urban Planning M206A – Intro to GIS March 19, 2012

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INTRODUCTION

THE FACTS• California has a significant agriculture industry.• California has a growing population.

OUR PROBLEM• Both crops and people need water.• Freshwater is a finite resource.

THE FUTURE• Who gets the water when both demands increase?• How will this impact California’s agriculture industry?

• SOURCES: Global ENSO SST Index (University of Washington)

YEAR 2000moderate La Niña

(dry weather)

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CROP VALUE: STATES

• SKILLS: graduated symbols, aggregating attribute fields (Crop Value = Field/Misc. Crops + Fruits/Nuts + Commercial Vegetables)• SOURCES: UCLA Mapshare State and Country Boundaries, US Department of Agriculture (2000 Crop Values), 2000 US Census Bureau

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CROP VALUE: US VS. CA

$2.8

$7.0

$5.6

California($15.5 billion)

Field and Misc. Fruits and NutsComm. Vegetables

$66.9

$12.4

$10.8

United States($90.0 billion)

Field and Misc. Fruits and NutsComm. Vegetables

in billions

• SKILLS: EXCEL pie charts• SOURCES: US Department of Agriculture (2000 Crop Values)

1) ~17% of US total crop value2) >50% of US crop value for both commercial vegetables and fruits and nuts

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POPULATION PROJECTIONS

2010

2020

2030

2040

2050

0% 10% 20% 30% 40% 50% 60% 70% 80%

8%

30%

45%

60%

76%

% Change from 2000

Year

• SKILLS: EXCEL bar chart, inset map, graduated symbols, creating indices (fractional population change)• SOURCES: UCLA Mapshare County, State, and Country Boundaries; California Department of Finance (2000 population & decadal projections)

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EVALUATIONMETRICS• Agricultural Water Demands• Domestic Water Demands• Irrigation Efficiency (proxied by evapotranspiration)

SCALES• Spatial: county• Temporal: monthly, annual, decadal

SIMPLIFYING ASSUMPTIONS• Water conservation efforts were not considered.• Climate variability (and climate change) were not considered.

– Total available water is fixed.• Other water uses (industrial, thermoelectric, mining, etc) assumed constant.• Freshwater sources and transport (via aqueducts) were not considered.

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IRRIGATION EFFICIENCYEvapotranspiration

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RECALL: WHAT IS EVAPOTRANSPIRATION?

ET = Evaporation + (Plant) Transpiration

Sufficient H20 ↑ crop growth (↑ ET) = ↑ crop value($)

Where does the H20 come from?– Native (rainfall, groundwater, etc)– Irrigation (imported water)

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WEATHER STATIONS

• 224 stations total

• 94 stations with data for year 2000

Use CIMIS data to calculate ET

(Currently, 141 active and 83 inactive)

• SKILLS: inset map, original data (CIMIS station locations)• SOURCES: UCLA Mapshare County, State, and Country Boundaries, California Department of Water Resources (2000 Irrigated Crop Acres and Water Use),

California Irrigation Management and Information System (station locations and period of record)

MONTHLY EVAPOTRANSPIRATION

12

WIN

TER

SPRI

NG

MONTHLY EVAPOTRANSPIRATIONSU

MM

ERFA

LL

13

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STATISTICAL SIGNIFICANCE

SPATIAL AUTOCORRELATION• z-score = 9.41:

>99% likelihood that pattern is NOT random• Moran’s Index = 0.323:

values have some correlation

• SKILLS: graduated symbols, hot spot analysis, aggregating attribute fields (annual = ∑monthly), model (kriging and clip), analysis (kriging), spatial statistics (spatial autocorrelation [Moran’s Index])

• SOURCES: UCLA Mapshare County, State, and Country Boundaries; California Irrigation Management and Information System (locations and annual ETo)

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MODELED EVAPOTRANSPIRATION

• SKILLS: creating indices (AW Efficiency = ETAW/AW), aggregating attribute fields (Applied Water = ΣAW for all 20 crop types), graduated symbols• SOURCES: UCLA Mapshare County, State, and Country Boundaries, California Department of Water Resources (2000 Irrigated Crop Acres and Water Use)

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FUTURE IMPACTSWater Volume and Total Crop Production Value

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WATER VOLUME: COUNTY

• SOURCES: UCLA Mapshare County, State, and Country Boundaries; California Department of Water Resources (2000 Irrigated Crop Acres and Water Use)

* Linear projections based on % change in population in each county

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WATER VOLUME: STATEAGRICULTURAL WATER: Variable• In 2000, 30,497 Mgal/day yielded

$15.5 billion.• In 2050, 79,040 Mgal/day could

potentially yield $40.1 billion.DOMESTIC WATER: Minimum RequiredMAX AVAILABLE WATER: Fixed• 36,904 Mgal/day

WHICH CROPS GET WATER? • 25,049 Mgal/day is available for

agriculture.

2000 20500

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

90,000

100,000

6,407 11,855

30,497$15.5

79,040$40.1

California Water Use/Demand

AgriculturalDomesticMax. Available

Volu

me

(Mga

l/da

y)

25,049$??

deficit(53,991)

($??)

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PLANNING SCENARIOS

Scenario I: Maximize crop production by first watering crops with the highest irrigation efficiency

Scenario II: Maximize crop profit by first watering crops with the greatest crop value

Scenario III: Maintain crop diversity by applying a proportional reduction in agricultural water

Scenario IV: Specialize crops (focus on commercial vegetables and fruits & nuts) by first watering crops with the highest irrigation efficiency

Agricultural Domestic

HOW TO BALANCETHE WATER DEMANDS?

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EX. SCENARIO III: MAINTAIN CROP DIVERSITY Scenario III: Maintain crop diversity by applying a proportional reduction in agricultural water__________________________________

WHICH CROPS GET WATER? • 25,049 Mgal/day is available for

agriculture.

• Between 2000 and 2050, total crop production value would decrease by $2.4 billion.

2000 20500

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

90,000

100,000

6,407 11,855

30,497$15.5

79,040$40.1

California Water Use/Demand

AgriculturalDomesticMax. Available

Volu

me

(Mga

l/da

y)

25,049$13.1

deficit(53,991)($27.0)

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SUMMARY

• Freshwater is a finite resource (future demand >> supply).

• There are many different approaches on how to allocate the water available for agriculture. – Irrigation Efficiency (using ET) is a statistically significant, yet

complicated option. (It also depends on modeled ETAW values.)

• Results suggest that there will be a decrease in $$ generated from the agriculture industry.

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MODEL

• SKILLS: model creation (Kriging interpolation of annual precipitation and clipping to California boundary)• SOURCES: UCLA Mapshare County, State, and Country Boundaries; California Department of Water Resources (2000 Irrigated Crop Acres and Water Use)

Can also be applied to monthly ETo data in California.

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SKILLS

• Model• Measurement/Analysis• Original Data

• Inset Map• Graduated symbols• Aggregating attribute fields • Creating indices• Attribute subset selection• Distance

• Charts, images• Hotspot Analysis (Spatial Analyst)• Spatial Statistics• Time-based Analysis

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Questions?