Comparing Least-Cost Path and Circuit Theory Analysis for Modelling Maritime Mobility Across the...

Celia Prescott-Decie

GIS cost surface analysis has become the standard method for modelling past mobility. The most popular form of cost surface analysis is least-cost path analysis, which uses cost surfaces to chart single optimal paths between a set source and destination point. The limitations of least-cost path analysis are well-documented, and novel methods for modelling maritime mobility have been proposed to address them. The aim of this research is to apply one such method, circuit theory analysis, to the modelling of ancient seafaring over the Roman Levantine basin. More specifically, the purpose of this dissertation is to first apply circuit theory analysis to an archaeological context it has not been applied to before, and compare the results of this method to those of least-cost path analysis. Cost surfaces are prepared using wind data and representing the cost of sailing from the Roman coastal site of Berytus to destination points in Cyprus, Anatolia, Egypt and the Northern and Southern Levantine coastlines for the months of April, July, October, and January. These cost surfaces are then used to produce least-cost paths and current maps depicting maritime mobility across the Levantine basin. By modelling several potential pathways, current maps represent connectivity as occurring in fluid zones rather than over strictly-defined routes. The ‘blurriness’ of current maps means they are more capable of addressing common difficulties in modelling maritime mobility. However, least-cost paths and current maps react differently to differing weather conditions throughout the year, with the former showing far more variation in sailing routes. The implications of this research are then that the real strength of these methods is their use in complement. By continuing to apply new methods of modelling human-environment interaction in original contexts, and by setting them against more popular ones with known limitations, the newer methods are refined; their specific strengths and weaknesses identified so that their methodology can be continually adapted. Comparing methods of analysis forces the archaeologist to examine their biases when confronted with results that do not match, and thus understandings of connectivity in the past are further expanded.