The Guadalete River in the Transition from the Middle Ages to the Modern Age. A Proposal for the Restitution of its Riverbed and Navigability Conditions Based on GIS

The Bay of Cadiz, where the Guadalete River flows into the southwest of the Iberian Pen- insula, is a privileged area for studying anthropic and natural changes over time, thanks to various transformation processes and its rich historical cartography. The river was navigable from Roman times, forming a wide estuary that gradually silted up. In medieval times, archival documentation at-tests to the difficulty of crossing the river with light boats to reach El Portal Port, for the commercial- ization of Jerez de la Frontera wines. In this article, we model the landscape of the lower basin of the Guadalete, analysing the processes that influence its clogging. To do so, we resort to the creation of a Digital Terrain Model from LiDAR data. We propose a method for the restitution of the topography at a given historical moment, the use of historical cartography to establish the drift of the riverbed and an analysis of the natural (geology, hydrology, tides, catastrophic events) and anthropic (mills, salt works, ship ballast) factors that conditioned its navigability.