Elisa Guerra, Francesca Ventura - University of BolognaRichard L. Snyder - University of California, Davis

Crop Coefficient to adaptfor Climate Change impact on Evapotranspiration

Climate Change is a Global issue! As the water available for agriculture becomes limiting due to population growth, competition from other water users, drought and water quality degradation, water use efficiency is primary important.

Evapotranspiration (ET) - the process by which water is directly lost from soil evaporation (E) and transpiration(T) from the surfaces of plants -is a major component of water use in agriculture.

Introduction

(http://www-naweb.iaea.org/nafa/news/water-management.html)

ET= Radiation + Aerodynamic

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The Penman-Monteith Equation

( ) ( )

++∆

−+−∆=

−

a

c

aspan

r

r

reecGRE

1

1

γ

ρλ

How to compute Kc values?

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Calculate ETo

Single Kc method Dual Kc method

ETc = Kc * ETo

Goal of this study?

Developing a Crop Coefficient Model in order to calculate ETo for computing actual ETc and possible ETc for hypothetical futureclimate conditions.

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Model Description:Crop distinction

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NN°°°°°°°° TYPETYPE

11 Seasonal field cropsSeasonal field crops

22 Annual field cropsAnnual field crops

33 TreesTrees and and vinesvines

44 Subtropical treesSubtropical trees

7

Type 1- Field & Row Crops

75%

10%

SEN

E

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70% SEN

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Deciduous Orchard & Vine Crops

Crop info

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Irrigation frequency

ExampleExample ((CornCorn): ): Depletion maxDepletion max = 150 mm= 150 mm

Field Crops & Trees

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Wetted area surface

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Immature crops and cover crops contribution

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Correction for climateeffect on mid-season

Kc

1-3 m/sLight to moderate wind

> 5.0 m/sStrong wind

3-5 m/sModerate to strong

wind

< 1.0 m/sLight wind

Mean monthly windspeed at 2 m

Description

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( ) ( )[ ]3.0

2 345004.0204.0

−−−+= cnctabcmid

hRHuKK

Fao Irrigation and Drainage Paper No. 56 “Crop evapotranspiration – Guidelines for computing crop water requirements”.

Kc curve: rainfall and irrigation effects

Maize; full sprinkler irrigation 14/18

Daily ETc curve

Maize; full sprinkler irrigation15/18

Cumulative ETc curves

Maize; full sprinkler irrigation.

..Next steps!

• Validation of the model with field data for wheat: data collected from “Modified”weather conditions (CRA, Bari).

• Test the model with measured data of stomatal resistance (rs), from plants grownon higher CO2 concentration.

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..Thank you!

Literature & Websites

A. J. Bloom, Global Climate Change, Convergence of Disciplines

Allen, R.G., Pereira, L.S., Raes, D., and Smith, M. 1998. “Crop evapotranspiration. Guidelines for computing crop water requirements.” Irrig. & Drain. Paper No. 56, United Nations, FAO, Rome.

Cayan, D. Luers, A.L., Hanemann, M. and Franco, G. 2006. Scenarios of climate change in California: An overview. California Energy Commission, CEC-500-2005-186-SF

CChaouche, K. Neppel, L., Dieulin, C., Pujol, N., Ladouche, B., Martin, E., Salas, D., Caballero, Y. 2010. Analyses of precipitation, temperature and evapotranspiration in a French Mediterranean region in the context of climate change. Comptes Rendus Geoscience, 342, 3:234-243.

Prentice I, Farquhar G, Fasham M, Goulden M, Heinmann M, et al. 2001. The carbon cycle and atmospheric carbon dioxide. In Climate Change 2001: The Scientific Basis. Contributions of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change, ed. JT Houghton, Y Ding, DJ Griggs, M Noguer, PJ van der Linden, et al., pp. 183–238. Cambridge, UK: Cambridge Univ. Press

Long, S.P., Ainsworth, E.A., Rogers, A. and Ort, D.R. 2004. Rising atmospheric carbon dioxide: plants FACE the future. Ann. Rev. Plant Biol. 55, 591-628.

Roderick and Farquhar 2002. The cause of decreased pan evaporation over the past 50 years. Science 298: 1410-1411.

Snyder, R.L., and Pruitt, W.O. 1992. Evapotranspiration Data Management in California, Proc., Water Forum '92 - Irrig. & Drain. Session, ASCE, New York, N.Y.

http://www.epa.gov/

http://www.fao.org/

http://micrometeorology.unl.edu/

http://biomet.ucdavis.edu/

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