Abstract
Ho Chi Minh City (HCMC), one of Southeast Asia’s fastest-growing megacities, has expanded its road networks, sluice gates, and flood-control structures in response to rapid urbanization and rising climate risks. While these grey-infrastructure interventions aim to protect the city, they have increasingly altered natural hydrological processes by reducing permeable surfaces, fragmenting wetlands, and obstructing water-retention zones. This study employs an integrated approach which combines literature review, long-term hydrological data, multi-temporal satellite imagery, field observations, and resident interviews, to examine how infrastructure expansion reshapes flooding patterns and ecological systems. Results show significant upward trends in river and tidal water levels (0.4–0.9 cm/year), a dramatic increase in impervious surfaces from 24 to 291 km2 (1985–2020), and wetland losses exceeding 90% since 1990. Extreme rainfall events delivering over 100 mm in three hours now occur annually, outpacing the city’s outdated drainage design. Subsidence rates of up to 8 mm/year further compound flood risk, particularly in low-lying districts. Resident surveys indicate widespread flood impacts and limited awareness of nature-based solutions. These findings highlight how infrastructure driven hydrological disruption, combined with climate pressures, heightens urban flood vulnerability. The study underscores the need for ecosystem-based planning by restoring green–blue networks, expanding retention spaces, and integrating nature
based solutions to build long-term resilience in HCMC and other deltaic cities. Keywords Flooding, Urban, Rainfall, Infrastructure, Megacities

https://link.springer.com/article/10.1007/s43621-026-02880-z