Monitoring archaeological sites in a changing landscape–using multitemporal satellite remote sensing as an ‘early warning’ method for detecting regrowth processes

Abstract

AbstractIn the coastal areas of North Norway farm abandonment followed by regrowth and reforestation is a major factor leading to landscape change. One consequence of this change is that archaeological sites are lost. A survey programme started by the Norwegian Directorate for Cultural Heritage in 1997, aimed at monitoring the condition of archaeological sites listed in the Norwegian National Sites and Monuments Record, has documented that regrowth processes represent a threat to the sites. The extent of the problem of regrowth and reforestation of archaeological sites is mostly unknown, however, and efficient coping strategies are not developed. In this article we present a change detection method based on the use of the Normalized Difference Vegetation Index (NDVI) applied to Landsat images with different acquisition dates, followed by image differencing. This procedure results in an easily interpretable and extremely quick approach to change detection of land cover as well as change in biomass, and it can be used as a ‘first warning’ method to indicate archaeological sites threatened by regrowth processes. The method as it is applied in this study appears to be most suitable for monitoring changes in the infield areas where contrasts are clearest. Further development is possible, both at the regional level using medium resolution satellite remote sensing where the aim is to detect significant changes in the agricultural as well as the cultural landscape, and at the site level, where use of the same method on data from high‐resolution sensors will allow monitoring of the site on a very detailed scale. Copyright © 2007 John Wiley & Sons, Ltd.