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Universidade de Lisboa (2018)

Desenvolvimento de mapas de vulnerabilidade da agricultura à seca em Portugal

Alonso, Catarina Alexandra Preto

Titre : Desenvolvimento de mapas de vulnerabilidade da agricultura à seca em Portugal

Auteur : Alonso, Catarina Alexandra Preto

Université de soutenance : Universidade de Lisboa

Grade : Mestrado em Ciências Geofísicas 2018

Agricultural drought, caused by a decrease in availability of soil moisture for crops, leads to a considerable economical loss around the world, threatening food security and sustainable agriculture. In the context of sustainable agricultural management, monitoring of drought events as well as assessing the vulnerability of agriculture plays a crucial role to drought events. This work intends the development of two methods based on drought indicators that, in turn, will allow to define indexes of exposure, sensitivity and adaptability of the agricultural system to drought events with the final goal of generating maps of vulnerability of agriculture to drought in mainland Portugal. The use of different indicators of drought and vegetation indexes, as well as other auxiliary data, allowed the development of the vulnerability index of drought agriculture (ADVI), based on a categorical methodology (Murthy et al., 2015a, b). In order to support the application of the categorical methodology, a principal component analysis (PCA) was performed based on the components previously used for the determination of ADVI. A preliminary analysis of drought indicator and vegetation health data was performed, using the indicator of drought SPEI (Standardized Precipitation-Evapotranspiration Index) and the vegetation health indexes VCI (Vegetation Condition Index), TCI (Temperature Condition Index) and VHI (Vegetation Health Index) for continental Portugal from September 1981 to August 2016, in order to understand the variability of the data used. Based on the analysis of these indices, it was verified that this data is consistent in years of drought. The computation of ADVI and the application of PCA were made considering first and only cereals for grain as agricultural crop and, later, considering the main agricultural crops. These methods identify five classes of vulnerability of drought agriculture : less vulnerable, moderately vulnerable, vulnerable, highly vulnerable and extremely high vulnerable. It can be concluded that both methods (ADVI and PCA) identify Minho and Alentejo as regions of low and extreme vulnerability, respectively. However, they also show some differences regarding the intermediate classes in other regions. Finally, it is verified that the vulnerability maps obtained have a pattern close to the standard of the aridity index.


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