Digital Surface Models (DSMs) of the Kajaki Dam, Afghanistan, Derived from 1952 Fairchild aerial photography and 2006 SPOT-5 HRG satellite imagery

This study applied historical aerial imagery and satellite imagery to create digital surface models (DSMs) of the Helmand River Valley situated in southwestern Afghanistan. The historical imagery, collected in 1952 by Fairchild Aerial Surveys Incorporated (FAS), at 1:40,000 scale, represents the earliest known aerial photographic archive of the Helmand Valley landscape. Structure-from-motion (SfM) multi-view stereo (MVS) photogrammetric techniques were used together with ground control points collected from high resolution satellite imagery to create a 5m digital elevation model (DEM) and 2m orthoimage. The historical DEM was evaluated for accuracy against a 2006 5m DEM using SPOT-5 HRG satellite imagery which was generated through stereo-autocorrelation techniques. The extraction of these historic data products are significant because they characterize the terrain and land cover of the valley at the time of the Kajaki (or Kajakai) Dam construction and prior to the expanding reservoir. Moreover, this study serves as one of a select few applications wherein historical imagery and DSMs derived from SfM techniques fill the gap of geospatial data prior to the era of satellite imagery coverage. The outputs of this study offer a glimpse into the Helmand Valley’s landscape, waterscape, and elevation in the 1950s, providing a digital historical dataset that can be used in present day research.