広州(China)

Historical tracking records verify that cyclone centers have approached within 90.8 km of the city (e.g., Noul with central pressure of 990.0 hPa and winds of 83.0 km/h).

South China Coastal Basin & Island Arc. Direct deep-water oceanic swell crashing onto shallow reef/bay systems.

The inverse barometer effect (approx. 1 cm sea level rise per 1 hPa pressure drop) combined with intense onshore wind stress pushes massive water masses across shallow continental waters, preventing natural tidal egress.

Coastal flood gates and frontline barrier dikes experience hydrodynamic loading far exceeding normal astronomical high tides. Ground floor structures in low-elevation zones face severe submersion risks.

Tropical cyclones entering the local coastal zone generate sustained gale-force winds exceeding 83.0 km/h with peak gusts surpassing 83.0 km/h.

Coastal flats 2–5m backed by hills; high exposure to rapid-intensification super typhoons.

As tropical cyclone winds transition from frictionless open ocean to rugged urban coastal surfaces, intense velocity shears and canyon aerodynamic funneling develop between street canyons and high-rise clusters.

Roof membranes, exterior curtain glass, rooftop HVAC units, and unanchored signage are subjected to localized negative pressure suction peaks (uplift failure).

Slow-moving or stalling cyclones within 300 km deliver multi-day cumulative precipitation commonly exceeding 250–500 mm within 24 to 48 hours.

Low-lying drainage outfalls discharging directly into tidal rivers or bays with minimal hydraulic gravity gradient.

When peak overland stormwater runoff coincides with storm surge wave setup, coastal river mouths become hydraulically choked (tailwater backwater effect), preventing stormwater egress and forcing water back into municipal conduits.

Inland lowlands and underpasses flood rapidly even before the storm center makes closest approach, cutting off secondary evacuation arteries.