Heatwaves or extreme heat events can be particularly harmful to agriculture. Grapevines grown in the Douro winemaking region are particularly exposed to this threat, due to the specificities of the already warm and dry climatic conditions. Furthermore, climate change simulations point to an increase in the frequency of occurrence of these extreme heat events, therefore posing a major challenge to winegrowers in the Mediterranean type climates. The current study focuses on the application of the STICS crop model to assess the potential impacts of heatwaves in grapevine yields over the Douro valley winemaking region. For this purpose, STICS was applied to grapevines using high-resolution weather, soil and terrain datasets over the Douro. To assess the impact of heatwaves, the weather dataset (1989-2005) was artificially modified, generating periods with anomalously high temperatures (+5 ºC), at certain onset dates and with specific durations (from 5 to 9 days). The model was run with this modified weather dataset and results were compared to the original unmodified runs. The results show that heatwaves can have a very strong impact on grapevine yields, strongly depending on the onset dates and duration of the heatwaves. The highest negative impacts may result in a decrease in the yield by up to -35% in some regions. Despite some uncertainties inherent to the current modelling assessment, the present study highlights the negative impacts of heatwaves on viticultural yields in the Douro region, which is critical information for stakeholders within the winemaking sector for planning suitable adaptation measures.
Authors: Helder Fraga1, João Santos1, Nicolo Clemente1, Teresa R. Freitas1, Aureliano Malheiro1, José Moutinho-Pereira1, Henrique Trindade1, Lia Dinis1, João Cerejeira2, Rita Sousa2, Cristina Carlos1,3, Igor Gonçalves3, Natacha Fontes4, António Graça4, Domingos Lopes1,5 and Aida Carvalho5,6
1Centre for the Research and Technology of Agro-Environmental and Biological Sciences, CITAB, Universidade de Trás-os-Montes e Alto Douro, UTAD, Vila Real, Portugal
2NIPE Centre for Research in Economics and Management, University of Minho, Braga, Portugal
3Associação para o Desenvolvimento da Viticultura Duriense, Edifício Centro de Excelência da Vinha e do Vinho Parque de Ciência e Tecnologia de Vila Real, Régia Douro Park, Portugal
4Sogrape Vinhos S.A., Avintes, Portugal
5Fundação Côa Parque, Vila Nova de Foz Côa, Portugal
6Instituto Politécnico de Bragança, CiTUR, Bragança, Portugal
Email: hfraga@utad.pt
Keywords: heat waves, viticulture, yield, Douro, Portugal, climate change
