Agent-based modelling for the study of shipwreck site formation processes: A theoretical framework and conceptual model.

Background Shipwreck site formation processes (SFP), their dynamics and transformation have long interested maritime archaeology from both a historical perspective and heritage management since shipwrecks constitute endangered cultural sites. Major contributions to shipwreck SFP have been made since the 1970s which conceive SFP from a systemic theoretical perspective, notably those of Keith Muckelroy and Martin Gibbs. However, to our view, such a perspective falls short in its capacity to explain and predict the distribution of elements in a shipwreck. In this article, we propose that shipwreck SFP can be understood from the theoretical framework of complex adaptive systems (CAS), where a SFP constitutes a CAS in which nonlinear interactions of natural and cultural factors give rise to the observed seabed distribution of a shipwreck as an emergent phenomenon. Methods From this theoretical framework, we propose agent-based modelling (ABM) as a suitable methodological approach for studying SFP. We show its implementation using the USS Somers, a 19th-century brig of war that sank in 1846 off the port of Veracruz, Mexico, during the Mexican-American War as a case study. The conceptual model was developed from the integration of historical data about the ship’s nautical characteristics and operation, information on the wrecking event from eyewitnesses, as well as modern environmental data. Results We present a conceptual model defining various elements that would constitute the Somers’ ABM. It gives specifics about the characteristics and variables regarding agents, global variables, processes, indicators, degradation and deposition sequences, and user interface. Conclusion The conceptual model served to develop ABM in a simulation platform where historical hypotheses can be tested and various possible scenarios of the SFP can be explored. By contrasting the simulation results with the archaeological record of the shipwreck, ABM would allow maritime archaeologists to postulate more supported and refined interpretations of a shipwreck’s SFP.