Tidal surges have often exceeded 1.8 metres at Phu An and Nha Be stations, submerging outfalls and undermining the effectiveness of the drainage system.
Land subsidence has also worsened, averaging about 2 centimetres a year, with some areas sinking 2-5 centimetres annually and up to 7-8 centimetres in densely built zones. Total subsidence commonly reaches 20-30 centimetres over 10-12 years, and in some places exceeds 50 centimetres.
The department said subsidence of 20-50 centimetres has lowered the effective design elevations of sewers, embankments and pumping stations, reducing their performance and leading to deeper and longer flooding during combined heavy rain, high tides and ground subsidence.
Financial resources for flood control remain limited, with the current budget meeting only about 30 per cent of needs and delaying many projects.
The city plans to implement 157 projects with total investment of nearly VND 348 trillion. So far, authorities have approved only 51 projects worth more than VND 158.26 trillion, which would allow the city to address just 72 of the 159 flood hotspots by 2030.
The department said only full funding of all 157 projects can resolve the city’s 159 flood hotspots, and called for coordinated development of embankments, tidal gates and reservoirs to strengthen urban drainage.