Hexagon KH-9 Imagery using Sunspot: Monitoring At-Risk Heritage and Development Pressure in Haryana India (1915-2021)

Abstract Archaeological mounds in Haryana, India, are being lost to agricultural intensification and urban growth, yet the most destructive decades fall between the two records commonly used to monitor them: early twentieth-century Survey of India maps and recent satellite products. We conduct a regional-scale application of declassified Hexagon (KH-9) panoramic imagery to heritage monitoring, using the updated Sunspot platform to georeference six 1975 frames with 20–25 ground control points each. Land cover for 1914-15 (maps), 1975 (Hexagon) and 2021 (ESA WorldCover) was classified independently, harmonized and compared within distance zones around twelve sites. Ground not classed as cropland fell from 35% of the observed area in 1915 to 14% in 1975 and 4% in 2021, whereas built-up land within 1 km of sites grew later and unevenly, reaching 75% at the most affected site. Separating these stages differentiates site-level risk and demonstrates the value of archival imagery and historical maps for heritage monitoring.