Mapping historical routes upon a geo-referenced late Ottoman coastal and land transport network

By Osman Özkan, Turgay Koçak,
Submitted to Session P4851 (Historical GIS applications to analyze economic geography and transport infrastructure in the Ottoman Empire, 2017 Annual Meeting
19th-21st Centuries;
LCD Projector without Audio;
There is no geo-referenced, queryable transport network for the Ottoman Empire. Taking ORBIS (The Stanford Geospatial Network Model of the Roman World, as an inspiration, we will design a pilot network. Our sources consist of historical nautical charts, and maps with land routes. Our geographical coverage will be today’s Turkey and our temporal focus the nineteenth century.

For the coastal network, we will design a corridor for navigation based upon maximum and minimum distances from the coast. It is conventional that coastal routes remain within outer borders of visibility range. The minimum distance to the coast for the routes is determined by the minimum depth of the sea. For the coastal network, we will first determine the outer limits of the navigation corridor using data on coastal visibility by making use of historical and current nautical charts. Secondly, we will use online available geo-referenced bathymetry data for the Mediterranean basin, and set a minimum depth to draw inner border of the corridor. Thirdly we will locate a selection of important harbors from the nineteenth-century and calculate variations of minimum distance routes among these harbors within the range of our designed corridor. Lastly, we will superimpose historical routes based upon log books among the same harbors and test the accuracy of our designed coastal transport network.

For the land transport network, again limiting our analysis to today’s Turkey we will geo-reference main land routes by rectifying historical maps from the nineteenth century as a first layer for our GIS analysis. As the second layer, we will integrate physical geography by using online available elevation data. In doing so GIS can calculate walking distance times in exact hours and minutes between points in routes. Lastly, we will map a selection of historical itineraries by making use of travel-time data in hours on foot, which are available in the statistical yearbooks from the nineteenth century. In doing so, for several routes, we can compare the travel times given in the historical sources with the calculated travel time by our GIS model between nodes of the land route network. This comparison will enable us to revise and refine our land route network.

Finally, for a case study we will integrate designed coastal and land transport networks for the district of Bursa and map the possible routes from the city of Bursa to Istanbul via harbors of Gemlik and Mudanya for the nineteenth century.