GIS Mapping Innovations for Documenting Change in Rural Cultural Landscapes

Image of report front cover

2017-15

The landscape research methods investigated in this project manipulate and evaluate remotely sensed data sources to provide information about change in rural cultural landscapes. The authors experimented with a variety of data sources and methods for spatial analysis and describe two promising methods here. One uses a method called pan-sharpening to compare historic aerial photographs with contemporary imagery in a georeferenced overlay to clarify changes in vegetation and other features between the two periods. The other method uses light detection and ranging (lidar) topographic data to aid in mapping terrain anomalies that indicate locations of historic roads and fences.

 

 Site

The case study project site exemplifies a range of typical conditions in rural landscapes in the Inner Bluegrass region of Kentucky. Auvergne is a large cattle farm that was historically the property of Brutus Clay and has remained in the Clay family since 1827. The farm’s gently sloping terrain is typical of the Bluegrass landscape (Figure 1). Land cover is largely pasture with remnants of savanna tree cover (Figure 2) and some tree lines along fences and drainage ways. Fences on the property include traditional dry-laid rock fences (Figure 3), made of quarried limestone, and wire fences. Wood fences would have coexisted with rock fences before the advent of wire. Relocation of some wood and wire fence lines has left remnant fence lines (Figure 4). Multiple farm roads, some relocated from former routes, traverse the property. The farm includes an intact building cluster surrounding the Clay house. This cluster includes remnants of an orchard and terraced gardens and a family cemetery. There are two non-extant building clusters, one a group of slave houses and the other an industrial complex. Extant and non-extant outbuildings are distributed widely across the landscape.

Results

a 1937 pan-sharpened aerial image overlaid on a 2016 aerial image.

The texturized 1937 image pan-sharpened with the 2016 image emphasizes the location of linear elements such as roads and fences, along with individual trees in pastures. In this image the white ghost marks have been inverted to black for clarity in the published image.

Pan-sharpened images created using 1937 aerial photographs and 2016 aerial imagery clearly revealed non-extant roads, fence lines, tree canopies, and buildings. The overlay image has the value of showing these non-extant features alongside features extant in both periods and those that are more recent in origin. Texturized and un-texturized versions of the pan-sharpened images provided both conspicuousness (the texturized image) and detail (the untexturized image.)

The lidar-derived topographic map of Auvergne revealed rock fences and roads – extant and non-extant – as linear ridge and swale signatures interrupting the consistent flow of contour lines. Tree canopy cover did not cause any discernable reduction in the clarity of these features on the topographic map. Non-extant wire fence locations were apparent but less obvious, with discontinuous indications in the topography that correlated with existing tree locations to locate fence lines. Remnant foundations, other collapsed materials, and graded level areas created noticeable topographic signatures at former building sites.

Conclusion

Pan-sharpened overlays of historic and contemporary aerial images and lidar-derived topographic maps both offer useful sources of information for cultural landscape research and preservation planning. Continuing development of methods to use GIS and remotely-sensed data promise to expand the range of tools available for cultural landscape analysis.

 

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