India, Sept. 14 -- There are now two Varanasis. One is the ancient city of temples, ghats and crowded, labyrinthine lanes along the Ganga. The other is its digital twin - a 160-sq-km digital replica built from LiDAR, aerial and drone imagery and 360-degree street-level scans, captured using light aircraft, backpack-mounted scanners and vehicles. It's a digital representation of the city, linked to real-world data and capable of being updated, analysed and used to simulate scenarios.

The ancient city is already putting new-age technology to work.

"Digital Twin has enabled us to identify areas likely to be hit by rising water levels, spot potential waterlogging zones, and flag houses that could be affected by floods, allowing officials to...