Measuring rice paddy persistence spanning a century with Japan's oldest topographic maps: georeferencing the Rapid Survey Maps for GIS analysis

Abstract

The Rapid Survey Maps, or Jinsoku Sokuzu, are the first series of topographic maps covering a large region drawn by modern surveying methods in Japan. These maps have no projection or map grid. To incorporate them into a historical GIS, analysts need to identify valid ground control points to georeference these maps, and identify features that are more likely to be distorted than other features. We studied the internal distortion in Rapid Survey Maps while carrying out an overlay analysis for rice paddies between them and a modern land use map. An irregular overall pattern of distortion implied that most were due to local surveying errors. In particular, long, thin rice paddy branches were distorted, leading to mismatches between rice paddies in the older maps with those in the newer map. This mismatch tended to exaggerate the area of rice paddies lost to non‐paddy land uses in the overlay analysis with a modern land use map.