Historical Floods and Territorial Planning: Lessons Learned and Opportunities Lost after the Santa Teresa Flood (1879) in the Segura Basin (Spain)

Historical cartography is one of the principal tools used in correct flood adaptation and management based on territorial planning. In fact, Directive 2007/60/EC on the assessment and management of flood risks includes the analysis and inventory of historical floods in a river basin for assessing the flood hazard and risk existing in a geographical space. This study seeks to analyse the largest flood registered in the Segura basin, occurring on 14–15 October 1879, which attracted enormous interest on a national and international level. The methodology applied is based on the consultation of historical sources and historical cartography, and the elaboration of maps using GIS, enabling comparisons to be made with current flood zones. The results show that the Santa Teresa flood was very similar to the Spanish National Cartographic Systems for Flood Areas (SNCZI) map for a 500-year return period. Furthermore, it allows the identification of the sensitive points along the course of the river or those prone to burst banks or overflowing, which practically coincide with the current maps and modelling conducted by the official bodies. Furthermore, the buildings in the floodable area in the historical cartography have been counted and reconstructed on a GIS map and the SNCZI. Massive anthropic occupation through the construction of settlements and infrastructures (hospitals, schools, centers for the elderly, roads and railways) in the Guadalentín valley and the Segura River increases the risk of flooding in the study area, despite the numerous control and regulation works carried out in the Segura River basin.