Ho Chi Minh City (HCMC) ranks among the top 10 cities in the world most likely to be severely affected by climate change. The city's flood management system is at the edge of its capacity. During the rainy season residents are confronted with flooding in the low lying areas and also in the central districts. The problems occur between August and December; at spring tide twice a month for several days in a row and twice daily. The main causes of flooding are high tide, heavy rain and high discharge from the Saigon and Dong Nai rivers combined with strong urbanisation. The flooding causes inconvenience and damages and needs a swift solution.  Land subsidence and increase of sea level rise and heavy rain due to climate change contribute to an even more difficult situation.

The Client commissioned Royal HaskoningDHV and Deltares for the formulation of strategies for alleviation of the flooding and inundation problems of HCMC. The Consultants proposed an integrated approach to flood and inundation management and strengthening of technical and management capabilities of the HCMC Steering Centre for Flood Control and relevant Vietnamese agencies with the aim to get control over the flooding and adapt to climate change, land subsidence and further urbanisation. Important elements are the assessment of a sewer improvement schedule (JICA) and a flood protection plan comprising over 170 km of dike reinforcement and 12 tidal gates in drainage canals and river mouths. Capacity building was an essential part of the assignment.

The project team has developed a SOBEK hydraulic model on a large scale, integrating the sewer system and the hydraulics in the rivers and canals. This results in an assessment of the existing flood system and provides perspective on the shortcomings and solutions. Existing plans (JICA, MARD, river and coastal tidal barriers as well as river diversions and canal discharge improvement) have been tested.

The team has proposed a long-term strategy and drawn up medium and short-term measures. In collaboration with the Peoples Committee the team has developed partnerships and identified funding sources for the implementation of future projects and strengthen the technical and management capabilities of relevant Vietnamese agencies. The project team will promote partnerships between Dutch and Vietnamese educational, scientific, water and environmental institutions and between governmental and non-governmental organisations in the field of water management.