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IVES 9 IVES Conference Series 9 Method for the evaluation of climatic changes envisaging the protection of grape-growing terroirs: the Géoviticulture MCC system in the evaluation of the potential impact of the construction of hydroelectric power plants on viticulture

Method for the evaluation of climatic changes envisaging the protection of grape-growing terroirs: the Géoviticulture MCC system in the evaluation of the potential impact of the construction of hydroelectric power plants on viticulture

Abstract

[English version below]

La recherche, conduite en 2002, a envisagé l’estimation, a priori, de l’effet du changement mesoclimatique sur le potentiel qualitatif de la région viticole de la Serra Gaúcha (Vallée du Rio das Antas) – Brésil, en fonction de la construction de 3 usines hydroélectriques. Avec une puissance totale de 360 MW, les usines seront opérationnelles entre 2004-2007. La superficie totale d’inondation est de 11,4 km2. La demande des viticulteurs était d’avoir une évaluation des effets d’un éventuel changement climatique en fonction de cette action humaine sur le potentiel viticole de la région. Elle présente climat IS-2 IH+1 IF-1 (humide, tempéré chaud, à nuits tempérées) selon le Système de Classification Climatique Multicritères Géoviticole (Système CCM Géoviticole). Le Système, qui offre plusieurs outils d’aide aux études de zonage vitivinicole à différents échelles, utilise 3 indices climatiques viticoles de référence (Indice de Sécheresse – IS, Indice Héliothermique – IH et Indice de Fraîcheur des Nuits – IF). Ces indices sont représentatifs de la variabilité du climat viticole liée aux exigences des cépages, à la qualité de la vendange (sucre, couleur, arôme) et à la typicité des vins. Dans une première étape, l’étude a été développée en utilisant la modélisation climatique numérique avec le modèle RAMS (Regional Atmospheric Modeling System), version 4.3, au niveau meso et macroclimatique dans la région des usines. Quatre situations ont été simulées : vigne au Fond de la Vallée – FV (situation juste à coté de la rivière) – (1) Climat Actuel (CA-FV) et (2) Climat Futur (CF-FV) ; Haut de la Vallée – HV (416 m supérieure en altitude et à une distance horizontale de 102 m para rapport à FV) – (3) Climat Actuel (CA-HV) et (4) Climat Futur (CF-HV). Le CF représente la situation de plus fort impact potentiel, où la superficie a être inondée sera la plus grande. Egalement, une étude de l’évolution du changement climatique à partir de la rivière jusqu’à la disparition de ces effets dans la région a été conduite. Les variables climatiques concernent les températures (minimale, maximale et moyenne), pluie, Rg, insolation, humidité de l’air e vitesse du vent ont été modélisées au pas de temps mensuel. L’évapotranspiration potentielle (ETP Penman) a été calculée. Par la suite, les indices IH, IF et IS ont été calculés, avec l’utilisation des fonctionnalités du Système, soit pour CA, soit pour CF dans les situations FV et HV. Les résultats ont montré que le climat viticole ne change pas de classe dans le climat futur. Pour l’IH au fond de la vallée, la valeur de 2.488 (CA-FV) passe à 2.483 dans le scénario futur (CF-FV). En haut de la Vallée, l’IH passe de 2.451 (CA) à 2.443 dans CF. Pour l’IF on ne constate pas un changement climatique pour la période de référence de l’indice (moi de mars), sauf pour la période de décembre à février, avec une augmentation de 0,1 à 0,2 ºC dans le climat futur pour les deux situations (FV et HV). L’IS présente des valeurs entre 4 à 6 mm supérieurs dans le climat futur en comparaison avec CA, soit pour FV ou HV. Le résultat est fonction surtout d’une précipitation un peut plus élevé et d’une ETP un peut plus faible dans le climat futur. L’étude a permis d’estimer que la construction des 3 usines hydroélectriques ne changera pas le macroclimat, mais devra causer un changement au niveau du climat local (topoclimat), en fonction d’une augmentation de l’IS et de la réduction de l’IF, restreint aux zones internes (coteaux de la Vallée du Rio das Antas). Le changement tend à zéro quand on s’éloigne de la vallée (plus de 1000 m de distance la rivière). Ce changement est potentiellement négatif vis-à-vis des caractéristiques qualitatives du raisin. Par contre, il est de très faible intensité. Une cartographie en 3D de la région des usines, avec la superficie a être inondé, a été saisie. Une suivie des conditions climatiques de longe terme est en cours envisageant l’évaluation du changement climatique réel et son influence sur la viticulture.

The research, conducted in 2002, has aimed at estimating, a priori, how the mesoclimatic change, conditioned by the construction of 3 hydroelectric power plants, will affect the qualitative potential of the grape-growing region of the Serra Gaúcha (Rio das Antas Valley), Brazil. The power plants will begin to operate between 2004 and 2007, and their total capacity will amount to 360 MW. The total inundation surface will be 11,4 km2. The vine growers requested to get an idea about how a possible climatic change, caused by this man-made action, could affect the vineyard potential of this region. According to the Géoviticulture Multicriteria Climate Classification System (Géoviticulture MCC System), the region has the climate IS-2 IH+1 IF-1 (“humid, temperate warm, with temperate nights”). The system, which offers several tools for viticultural zoning studies on different scales, employs 3 viticultural climatic indices of reference (Dryness Index – IS, Heliothermal Index – IH, and Cool Night Index – IF). These indices are representative of the variability of the viticultural climate related to the requirements of the grape varieties, the quality of the grapes (sugar, color, flavor) and the characteristics of the wines. In a first stage of the study, numerical climatic modeling with the RAMS (Regional Atmospheric Modeling System), version 4.3, was employed at the meso- and macroclimatic level in the region of the power plants. Four situations were simulated: vineyard at the foot of the valley – FV – (location right at the riverbanks) – (1) Current Climate (CA-FV) and (2) Future Climate (FC-FV); at the top of the valley – HV – (416m higher and at a horizontal distance of 102m in relation to FV) – (3) Current Climate (CA-HV) and (4) Future Climate (CF-HV). The CF demonstrates the situation with the strongest potential impact where the surface to be flooded is the largest. Equally, a study on the evolution of the climatic change was conducted starting from the river up to the disappearance of these effects in the region. The climatic variables, concerning the temperatures (minimum, maximum and average), rain, Rg, insolation, air humidity and speed of the wind were modeled at a monthly rate. The potential evapotranspiration was calculated. In the following, the indices IH, IS and IF were calculated, using the functions of the System, for CA as well as for CF in the situations FV and HV. The results have shown that the viticultural climate does not change class in the future climate. For IH at the foot of the valley, the value 2.488 (CA-FV) changes to 2.483 in the future climate (CF-FV). At the top of the valley the IH changes from 2.451 (CA) to 2.433 for CF. In this way, no significative influence on IH was observed. For IF it is not possible to observe a climatic change in the period of reference of the index (March) except for the period from December to February, with an increase of 0,1 to 0,2ºC in the future climate for the two situations (FV and HV). The IS shows values between 4 and 6 mm higher in the future climate when compared with CA, be it for FV or HV. The result is above all a consequence of a slightly higher precipitation and of a slightly weaker ETP in the future climate. The study has allowed to estimate that the construction of the three hydroelectric power plants will not change the macroclimate, but should cause a change at the level of the local climate (topoclimate), as an effect of an increase of the IS and of the reduction of the IF, restricted to internal areas (slopes of the Rio das Antas Valley). The change tends towards zero at a certain distance from the valley (more than 1000m distance from the river). This change is potentially negative for the qualitative characteristics of the grapes. However, it is of very weak intensity. A 3D chart of the power plants region with the surface to be flooded has been produced. A study on the long-term climatic conditions is currently being performed aiming at the evaluation of the real climatic change and its influence on the viticulture.

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Publication date: January 12, 2022

Issue: Terroir 2004

Type: Article

Authors

J. Tonietto (1), O.L.L. de Moraes (2) et H. Hasenack (3)

(1) Embrapa – Centre National de Recherche de la Vigne et du Vin ; Rua Livramento, 515 ; 95700-000 –
Bento Gonçalves, Brésil
(2) Département de Climatologie, Université Fédérale de Santa Maria – UFSM
(3) Centre d’Ecologie, Université Fédérale du Rio Grande do Sul – UFRGS

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Keywords

Qualité, changement climatique, impact climatique, Système CCM Géoviticole, protection des terroirs viticoles

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IVES Conference Series | Terroir 2004

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