Utilising Declassified Cold War Satellite Imagery (KH-9 Hexagon) for Remote Sensing of Historic Hydraulic Management Features in North Africa

Since its declassification by the United States in 1995, imagery from Cold War Era (1947-1991) satellite programmes has become a powerful remote sensing tool. The scientific community has employed this imagery for a multitude of environmental and landscape studies since it became publicly available. Archaeologists first utilised imagery from the CORONA programme to locate unrecorded archaeological sites in the Middle East and have continued its use elsewhere. The final Cold War satellite programme, KH-9, codenamed HEXAGON (1971-1986), was declassified in 2011 but made publicly available from the United States Geological Survey (USGS) in 2022. The characteristics of HEXAGON imagery make it a better tool than CORONA for cultural heritage studies, especially those that wish to document landscape and site change. This paper presents a brief overview of a methodology to accurately orthorectify the KH-9 imagery and the documentation of traditional water management features such as the underground abstraction galleries (khettara) in Skoura Oasis, Morocco.