Articles
Projected impacts on irrigation demand of almonds and wine grapes in the Murray Darling Basin: integrating climate change modeling and expert knowledge
Article number
1468_6
Pages
37 – 44
Language
English
Abstract
Climate change is expected to reduce supply and increase demand for irrigation across the Murray-Darling Basin.
Perennial crops, such as almonds and winegrapes are especially exposed due to their lifespan of 20 plus years.
To better understand current irrigation practices and the potential to adapt to increases in irrigation demand, we interviewed industry experts on current irrigation use and variation due to management and season for each crop.
Reference crop evapotranspiration (ET0) is the key aspect of climate that affects irrigation demand; however, while the impact of climate change on ETo is known, scaling future ET0 data to irrigation requirements (ML ha-1) is poorly understood.
ETo was calculated using the FAO-56 Penman-Monteith method from a representative selection of global climate models and contrasting low (SSP1-2.6) and high (and SSP3-7.0) emissions scenarios.
Crop coefficients for almonds and winegrapes were benchmarked and then used to estimate the historic and future irrigation requirements.
Estimated irrigation demand increased by between 10 and 20% by 2070, depending on the crop and the emissions scenario.
This transferred into an increase in irrigation requirements of up to 2 ML ha-1 in the longer term (2051-2070) under the higher emissions scenario.
The increase was less than expected, as the modeled impact of climate change on two key determinants of ET0, wind speed and radiation, was small in the case study region.
The increase in irrigation demand compares favorably with potential irrigation savings due to current management practices identified as part of the expert interviews, of between 1.5 and 2.5 ML ha-1. The increased demand will be a headwind for the almond and wine industries, especially in years of low supply and high water cost; however, there appears to be adaptive management options that will cope with this challenge.
Perennial crops, such as almonds and winegrapes are especially exposed due to their lifespan of 20 plus years.
To better understand current irrigation practices and the potential to adapt to increases in irrigation demand, we interviewed industry experts on current irrigation use and variation due to management and season for each crop.
Reference crop evapotranspiration (ET0) is the key aspect of climate that affects irrigation demand; however, while the impact of climate change on ETo is known, scaling future ET0 data to irrigation requirements (ML ha-1) is poorly understood.
ETo was calculated using the FAO-56 Penman-Monteith method from a representative selection of global climate models and contrasting low (SSP1-2.6) and high (and SSP3-7.0) emissions scenarios.
Crop coefficients for almonds and winegrapes were benchmarked and then used to estimate the historic and future irrigation requirements.
Estimated irrigation demand increased by between 10 and 20% by 2070, depending on the crop and the emissions scenario.
This transferred into an increase in irrigation requirements of up to 2 ML ha-1 in the longer term (2051-2070) under the higher emissions scenario.
The increase was less than expected, as the modeled impact of climate change on two key determinants of ET0, wind speed and radiation, was small in the case study region.
The increase in irrigation demand compares favorably with potential irrigation savings due to current management practices identified as part of the expert interviews, of between 1.5 and 2.5 ML ha-1. The increased demand will be a headwind for the almond and wine industries, especially in years of low supply and high water cost; however, there appears to be adaptive management options that will cope with this challenge.
Authors
D.S. Thomas, P.R. Petrie, P.T. Hayman, A. Hall
Keywords
almond, crop coefficient, crop demand, evapotranspiration, grape, irrigation
Groups involved
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