Climatic and social factors behind the Spanish Mediterranean flood event chronologies from documentary sources (14th–20th centuries)

The Spanish Mediterranean river basin provides a good background for studying floods from documentary and bibliographical sources within the specialty of historical climatology. This study region's long history of human occupation and climatic conditions together determine a high risk of flooding. As a result, there exists an enormous amount of documentary heritage containing flood information. However, the heterogeneity of documentary sources and different approaches to classifying floods through historical documents can generate some biases and uncertainties about the quantity and quality of the available data. For this reason, this paper proposes a methodology for reconstructing historical floods based on cross-referencing documentary sources. This approach, together with additional archival work, has allowed us to increase the number of flood series for the Spanish Mediterranean coast by 17% and has generated a surprising increase of 233% in the number of flood cases detected. The data obtained have allowed us to analyze the variability of floods and their relationship with climatic and social factors from the fourteenth century to the present. Different climatic oscillations related to the Little Ice Age are detected between the 14th and 19th centuries. Additionally, we detected a strong influence of the defense infrastructures and urban growth, which explain the recent flood trends. However, the difficulty in analyzing the influence of social factors on long-term flood behavior invites us to reflect on the need for further work for emphasizing these issues.This work has been partially supported by the Spanish Ministry of Economy and Innovation (CGL2016-75996-R). SG-G acknowledges the support of the Spanish Ministry of Science, Innovation and Universities through “Juan de la Cierva-Incorporación” grant (IJCI-2016-29016). AA acknowledges the support of the Spanish Ministry of Economy and Innovation (HAR2017-82810-P). MB acknowledges the support of the Research Group of Generalitat de Catalunya “Paleogeoecologia, Riscs Naturals i Gestió Ambiental (PaleoRisk)” (2017SGR1106)