A Preliminary Assessment of Crop Production and Estimated Irrigation Water Use for

Chihuahua, Mexico

Presented at

“Free Trade of the Americas, the WTO and New Farm Legislation:

Responding to Challenges and Opportunities”

San Antonio, Texas, May 24, 2002

Parr Rosson, Aaron Hobbs, and Flynn Adcock

Texas A&M University

Background

• U.S. - Mexico 1944 Water Treaty• Mexico to Deliver 350,000 Acre Feet (AF) to the

U.S. Annually from Rio Grande• Mexican Deficits Began in 1995• Currently a cummulative Debt of

Approximately 1.5 Million AF• U.S. to Deliver 1.5 Million AF to Mexico Per

Year from Colorado

Methodology

• Annual Production, Acreage and Yield Data Collected from SAGARPA for the Entire State of Chihuahua, Mexico

• Analysis of Trends

• CropWat Version 7

• Penman-Monteith Method

CropWat

• Estimated Evapotranspiration Rate (ETo) Calculated for Chihuahua, Mexico

• Rainfall Measured for Chihuahua, MX• Medium Soil Type• Irrigation when 25% of ETo, to refill to soil

capacity• Plant date set by crop• Irrigation Efficiency estimated at 50%

Penman-Monteith

• Penman-Monteith Monthly ETo Calculated for Chihuahua by CropWat

• Coefficients from FAO

• Multiplied the monthly ETo by the Coefficient For the Season then Subtracted Out Rainfall for the Time Period

Harvested Acres in Chihuahua, MX1980 - 1999

Source: SAGARPA; Total for 31 crops included in study.

555651

745 728 732

1106

832750

1980 1985 1990 1995 1996 1997 1998 19990

200

400

600

800

1000

1200

1400

Thousand Acres

Production in Chihuahua, MX1980-1999

Source: SAGARPA; Total for 31 crops included in study.

1.05

1.63

2.212

2.723.123

4.274

3.059 3.025

1980 1985 1990 1995 1996 1997 1998 19990

1

2

3

4

5

Million MT

Average Yield in Chihuahua, MX1980-1999

Source: SAGARPA; Average for 31 crops included in study.

1.88

2.51

2.97

3.74

4.263.86

3.684.03

1980 1985 1990 1995 1996 1997 1998 19990

1

2

3

4

5

MT/Acre

Percent Increases in Harvested Acres, Production and Yield for Chihuahua

For Major Crops

1980-1999 1990-1999 1995-1999Harvested Acres 35% .72% 3.13%

Production 191% 36.72% 11.21%

Yield 114% 35.74% 7.84%

Source: SAGARPA; Increases for 31 crops included in study.

Crop Acreage, 1999

• Corn• Alfalfa• Cotton• Pecans• Apples• Dry Beans• Bell Peppers

Source: SAGARPA

Total Acreage: 750,430 MT

Corn20.4%

Alfalfa15.3%

Cotton10.7%

Pecans8.7%Apples

7.6%Dry Beans

5.3%

Green Peppers5.2%

Others26.8%

Estimated Irrigation Water Use in Chihuahua, 1980-1999

Estimates: CropWat and CNAS; Total of 27 crops included in study.

1.21.4

1.61.5

1.6

2.3

1.81.6

1980 1985 1990 1995 1996 1997 1998 19990

0.5

1

1.5

2

2.5

Million Acre Feet

Estimated Irrigation Water Use in Chihuahua, MX 1999 (1,000 acre feet)

Estimates: CropWat and CNAS; Total of 27 crops included in study.

Corn294

Alfalfa261

Cotton224

Apples194

Pecans175 Bell Peppers

73

Others362

Total: 1,581taf

Estimated Alfalfa Irrigation Water Use1990 - 1999

Source: CropWat & CNAS estimates

258228

187

291

248261

1990 1995 1996 1997 1998 19990

50

100

150

200

250

300

350

Thousand Acre Feet

Estimated Corn Irrigation Water Use1980 - 1999

Source: CropWat & CNAS estimates

118156

243 238

282

440

339

294

1980 1985 1990 1995 1996 1997 1998 19990

100

200

300

400

500

Thousand Acre Feet

Estimated Cotton Irrigation Water Use1980 - 1999

Source: CropWat & CNAS estimates

263

201230

248

346

442

389

224

1980 1985 1990 1995 1996 1997 1998 19990

100

200

300

400

500

Thousand Acre Feet

Estimated Apple Irrigation Water Use1980 - 1999

Source: CropWat & CNAS estimates

191

144 148

178164

195

149

194

1980 1985 1990 1995 1996 1997 1998 19990

50

100

150

200

250

Thousand Acre Feet

Estimated Pecan Irrigation Water Use1980 - 1999

Source: CropWat & CNAS estimates

55

82

114

145 151 147163

175

1980 1985 1990 1995 1996 1997 1998 19990

50

100

150

200

Thousand Acre Feet

Estimated Bell Pepper Irrigation Water Use1980 - 1999

Source: CropWat & CNAS estimates

26 2533

58 58

121

93

73

1980 1985 1990 1995 1996 1997 1998 19990

20

40

60

80

100

120

140

Thousand Acre Feet

Selected 2001 Irrigation Water UseEstimates

Source: CropWat & CNAS estimates

368

292

31

94

8

16

24

Corn

Alfalfa

Dry Beans

Bell Peppers

Tomatos

Onions

Watermelons

Thousand Acre Feet

0 100 200 300 400 500

Further Research

• Update 2000 and 2001 Data for All Crops

• Change Efficiency Levels For a Range of Estimates

– Determine Efficiency of Delivery of Water to the Farm

– Determine Application Efficiency in the Field

• Factor Yields Into Irrigation Requirements Equation

• Determine the proportion of ground water use and surface water use

Conclusions

• Total Acreage and Production have continued to increase since the drought began in 1995.

• Lower Rainfall and Increased Water Use Have Reduced Flows to the Rio Grand.

• Analysis of Irrigation Districts Would Improve Estimates

Potential Solutions

• Improved Efficiency of Water Delivery and Use in Chihuahua

• Improved Efficiency of Water Delivery and Use in Lower Rio Grande Valley

• Form and Implement Effective Binational Water Management Planning