Where are the Shipwrecks of the Zuiderzee? A new version of the Shipwreck Database Flevoland (3.0), based on spatial and archaeohistorical research into wreck sites in the province of Flevoland

For several decades, maritime archaeologists, state authorities and maritime-archaeological companies have worked with an outdated and inaccurate dataset (with regard to position and presence) concerning shipwrecks in part of the Zuiderzee region. The information about these wrecks was scattered over multiple databases (both analogue and digital), documenting different numbers of shipwrecks across Flevoland. In order to gain a clear and accurate overview of the shipwrecks that were discovered in the former Zuiderzee, the Shipwreck Database Flevoland (SDF) was compiled. The third version of this database is presented in this article and is mainly aimed at documenting the present condition of shipwreck sites (wrecks in situ, removed or unknown) and the accuracy of the coordinates that mark the location of the shipwreck (exact, approximate or unknown). The excavation documentation of the shipwrecks was used for retrieving accurate descriptions of wreck sites, although in most cases these descriptions referred to drainage ditches and other local topography that since have been removed or altered. Historical aerial photographs, LiDAR data and satellite images were used for tracing the course of lost but relevant drainage ditches and the exact locations of shipwrecks. Multiple wreck sites were discovered in the aerial photographs, in the form of crop- and soil-marks revealing either wrecks or former excavation trenches. These visible wreck sites correspond perfectly to the locations mentioned in the research reports and prove the accuracy and feasibility of the used methodology. The new version of the SDF therefore provides more accurate distribution and density maps of wreck sites in the province of Flevoland, which is of importance for spatial maritime archaeological research. Furthermore, the newinformation on the accuracy and presence/absence of shipwrecks can be used in archaeological heritage management. Only shipwrecks that are still present in the former seabed, and whose recorded location is reasonably accurate, can be effectively protected.