Hydrogeological context and hydrogeoarchaeological heritage associated with the La Mota Fortress (Alcalá la Real, province of Jaén, southern Spain)

Abstract

La Mota Fortress is a medieval military enclosure erected on the upper part of the homonymous hill, in Alcalá la Real (province of Jaén, southern Spain). Although previous vestiges have been found, the fortress reached its greatest splendour during the Nasrid-dynasty period (13th and 14th centuries). Its geographical location, in the limit between the old Christian and Muslim kingdoms, conferred a great strategic value to this military complex as a defensive bastion in the northern border of the ancient Kingdom of Granada. This fact caused the citadel to repeatedly be besieged and its inhabitants put into practice a particular system for water supply, based on the combined use of groundwater, stored in the calcareous sandstones of Tortonian age, and rainwater, collected in numerous cisterns sited within city walls. In this paper, the potential interest of this particular supply system is analyzed and discussed. To this end, we describe the hydrogeological functioning of the small aquifer on which the Nasrid fortress was built, and the system of underground wells and galleries that was hidden inside. In addition, the water resources and possible groundwater reserves are evaluated and their physico-chemical characteristics are detailed. Finally, the relevance in the water supply system of one of the most significant withdrawal facilities (Pozo de la Conquista) is analyzed, as well as the role played by the well in the conquest of the city by the Christian troops of Alfonso XI.