Author(s): Alejandro Gomez Tejera

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Abstract: Across many cities worldwide, rivers have been straightened, embanked and converted into open sewers. Rapid, weakly regulated urbanisation has increased paved surfaces and wastewater loads while concentrating low-income residents in marginal land along river corridors (Castaldo et al., 2025). Climate projections point to rising urban flood exposure, particularly in Asian cities where dense settlement patterns intersect with intense monsoon regimes (Zhang et al., 2025). In Kathmandu, decades of urban expansion have reconfigured a river system once structured through the hiti-pokhari regime, a vernacular water management system attuned to seasonal hydrology (Gautam et al., 2018). The Bagmati basin is now heavily polluted and hydraulically constrained by embankment works. Infrastructure development and land reclamation have altered topography and drainage patterns across the basin (Shrestha et al., 2025). These transformations increase flood hazard by reducing conveyance and obstructing flow paths, while urbanisation expands into low-lying areas.

DOI: https://doi.org/10.64697/iahr.proc.ise2026.abs.282

Year: 2026