Reading Urban Ground Instability Through Traditional Water Infrastructure: Evidence From Historic Bhaktapur, Nepal

Abstract

Urban ground instability in rapidly developing mountain valleys is often recognized only after cracking, settlement, waterlogging, drainage failure, or infrastructure damage occurs. Historic Bhaktapur in the Kathmandu Valley provides an opportunity to investigate these symptoms through its traditional water infrastructure. This study examines relationships among ponds, stone spouts (hitis), drainage routes, bridges, agricultural land, and settlements as indicators of changing ground and water conditions. Field observations were organized around Bhaktapur’s 33 Ponds, 99 Hitis, and 33 Bridges circuits, alongside observations of urban expansion, drainage alteration, agricultural-land conversion, waterlogging, and reported ground cracking. Traditional water infrastructure is interpreted not only as cultural heritage but also as a distributed record of historical hydrological conditions and landscape adaptation. Preliminary observations suggest that disconnection of ponds, recharge areas, drainage pathways, and traditional outlets may modify local water movement and increase vulnerability to waterlogging and localized ground instability. The study proposes a heritage-based engineering-geological framework integrating traditional water networks with present land use, drainage, settlement patterns, and visible ground disturbances to identify areas requiring detailed geotechnical and hydrogeological investigation.