|Authors: ||J. Marsal, A. Utset|
|Keywords: ||crop coefficient, CropSyst, evapotranspiration, soil depth|
The effects that climate change may have on full-irrigation vineyard requirements over the next 20 years were simulated by combining global circulation and crop models.
Climate change scenarios were obtained from the CGCM2 model outputs provided by the Canadian Center for Climate Modeling and Analysis according to the IPCC SRES A2 scenario for greenhouse gas emissions.
A historical 42 year series of weather data for Lleida (Iberian Peninsula) was used in combination with the LARS-WG weather generator to generate 100 realizations of local weather data corresponding to the years 2010, 2015, 2020 and 2025. Climate change scenarios were produced by perturbing the weather generator according to the CGCM2 results corresponding to the study site.
CropSyst was used to simulate vineyard water balance.
Crop water requirements were simulated from an automatic calculation implemented in the model which derived the amount of applied water that would maintain soil water content at field capacity while minimizing drainage according to a calculated daily routine.
Data from a vineyard irrigation experiment which considered fully irrigated and deficit irrigated vines were used to adjust the crop model parameters according to water requirements applying the FAO-56 method.
The model was validated by comparing simulations with experimental data for berry yield from six other different sites which differed in soil depth.
Crop coefficients simulated by CropSyst were successful at mimicking those produced by FAO-56. The weather generated indicated an increase in average air temperature of 1.5°C from 2005 to 2025. Reference evapotranspiration also increased by a maximum of 43 mm and rainfall decreased by 100 mm for the same period.
Accordingly, irrigation requirements increased by 50 mm and crop development (bud-break and harvest) advanced by two weeks.
The greatest impact, however, was on irrigation adjustments within the growing season, with crop coefficients increasing by 50% during early spring.
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