07-03, 15:25–15:50 (Europe/Amsterdam), Quantum 1
Language: English
This presentation explores a GIS-based method for quantifying changes in regional borders across selected African countries by leveraging historical cartographic data we did at Geodienst. Using QGIS, particularly the georeferencing tool and the Model Designer, historical and current borders are systematically analyzed to support spatial research on territorial transformation.
The analysis begins with georeferencing and digitizing historical paper maps. In this case, the snapping and tracing tools were used to significantly enhance accuracy and efficiency. Once all the layers were collected, including national borders, current regional borders and historical borders, the analysis could begin.
Firstly, the borders have to be buffered in different sizes to correct for the potential inaccuracies of historical maps. This would allow for the output to have different margins of error. Then, using a clip all historical borders within the current borders would be determined. Using the difference tool we can get the same borders but excluding the national borders to account for the lack of change there. Finally, using the sum line lengths we can get the lenght of those boundaries and calculate the percentage change.
This workflow demonstrates a replicable and scalable approach to historical border analysis using open-source GIS tools. The presentation will highlight key findings, methodological challenges, and potential applications in historical geography and political boundary studies.
Junior GIS Specialist at Geodienst