Flooding in Hanoi after heavy rain. Photo by Tin247

According to the city's drainage planning to 2030, Hanoi will also complete drainage systems in other residential areas and satellite urban sites in a bid to tackle flooding.

One of the solutions being considered is collecting rainwater.

Currently, the average annual rainfall in Hanoi is 1,676mm, higher than in previous decades due to climate change. In the future, the impacts of climate change will be included in calculating rainfall and drainage system planning.

A sewer system for both wastewater and rainwater is only in place in the inner city centre and some suburban districts include Ha Dong, Son Tay and Dong Anh.

Hanoi still has 25 locations that are often flooded by 50-100mm of rain. Even less than 50mm of rainfall can still cause flooding in low-lying areas and old sewers.

During the urbanisation process, little attention was paid to sewer systems and as a result, the old sewers and hydraulic systems are often overwhelmed and flooded by heavy rain.

Buildings inside the city will be required to have rainwater collection facilities such as underground reservoirs or gardens, and pavements will have absorbent material or slits for water to drain through.

Dry lakes, reservoirs and a green belt will also be built. Households will be encouraged to utilise rainwater for purposes such as watering plants and washing vehicles.