SITTING IN HIS BANGALORE OFFICE, sporting steel-rimmed glasses and a salt-and-pepper ponytail, 46-year-old Mohan Rao remembered his time working in Hampi. In 2002, the Archaeological Survey of India began conservation work at this World Heritage site in Karnataka, which was part of the capital of the Vijayanagara Empire until its decline in the sixteenth century and is still an important place of pilgrimage today. Among the structures the ASI team worked on was a pushkarini, or stepped tank, within the Vittala temple complex—the largest at Hampi. Archaeologists were puzzled when they failed to drain the pushkarini completely even after several days of pumping. How, they wondered, had such a large tank been fed, when there was no obvious water source at hand? Historical records showed that the ancient city did not use water from the nearby Tungabhadra River except for irrigation. Where, then, did it get its water?

As they searched for an answer, archaeologists uncovered numerous shallow ponds in the dry and rocky surrounding hills. But they could not understand what purpose these served. Rao, an environmental and landscape architect, was supervising work on Hampi’s gardens. He was intrigued, and evinced his interest. Working with the ASI team, he realised that the ponds were carefully placed to collect surface run-off water in a series of filtration pits. Channels then directed the filtered rainwater into the pushkarini. Tanks such as this provided for about half a million residents in the city’s heyday.

For Rao, this clever apparatus was no surprise. “Traditional societies, having no recourse to energy or mechanical systems, developed settlements which were fully integrated with the natural environment,” he said when we spoke in March. “The process of building settlements, being relatively slow, was invariably sensitive to management of resources.” Rao founded his company, Integrated Design, in 1994, as a landscape design firm, but following his interest in sustainable architecture he diversified into site and water management. In Hampi, he eventually joined the project to revive the pushkarini, and helped the ASI fully restore it in 2007. For this, he received the Award of Distinction at the UNESCO Asia-Pacific Awards for Cultural Heritage Conservation in 2010. He now applies what he learnt from studying the system at Hampi to numerous projects in India and across the world, including in Libya, Morocco, South Africa, France and China.