Workers of Hà Nội Sewerage and Drainage Company drain the water after the flooding caused by Typhoon Yagi in September. VNA/VNS Photo

HÀ NỘI - Flooding in urban areas has been a persistent problem of major cities in Việt Nam for many years. The reason has been blamed on drainage and wastewater treatment, which have run out of capacity and are not able to keep up with the pace of urbanisation.

Việt Nam now has 82 urban wastewater treatment plants located in more than 50 urban areas. They have a total design capacity of about 1.79 million cubic metres per hour, day and night, with an actual operating capacity of about 700,000 cubic metres per day and night.

The drainage system of residential areas in large cities and river basins is mostly over a shared system.

Domestic wastewater and rainwater are discharged directly into sewers, canals and ditches and then into the main rivers of the basins.

Most wastewater from toilets is pre-treated in septic tanks of each household before being discharged into the public drainage system.

When compared to other urban regions worldwide, Việt Nam's pipeline rate per capita is still low.

The rate in Việt Nam is roughly 0.5 metres per person, while the global average is two metres per person.

According to Lê Thu Thủy, deputy head of Drainage Management and Wastewater Treatment Sub-Department, Department of Technical Infrastructure Department of Technical Infrastructure under the Ministry of Construction, Việt Nam’s current drainage system in urban areas was built many years ago. It has decayed and many parts have not yet been fully upgraded. Rainwater and domestic wastewater are mixed together, discharged directly into sewers, canals, ditches, rivers and the sea.

Notably, urban flooding resulting from rain has occurred frequently in large cities since the 2000s and has become increasingly severe in terms of severity and frequency. The flooding period has lasted longer since 2010 and has become more complex and unpredictable.

Dr Nguyễn Việt Anh from Hà Nội University of Civil Engineering said there were currently many challenges in drainage and urban flood prevention in Việt Nam including limited public awareness towards drainage and wastewater treatment.

“They are not ready to adapt to climate change,” he said.

In many urban areas, the connection rate to the drainage system remained low while drainage and wastewater treatment service prices were too low, not covering the operating and maintenance costs, he said.

He pointed out other shortcomings including a downgraded drainage system and soil, groundwater and surface water pollution due to wastewater discharge.

The lack of financial resources to implement drainage and wastewater treatment projects was ongoing while resilience and adaptation remain limited, he said.

Experts hold that it is necessary to build and issue laws regulating drainage, regarding the important role of clean water, drainage in flood prevention, wastewater collection and treatment.

To create a legal corridor for the development of green and sustainable drainage infrastructure, the Government needs to pay more attention to water supply and drainage, wastewater treatment through the establishment of a legal framework, technical standards and national orientations, say the experts.

According to Dr Lưu Đức Hải, director of the Institute for Urban Research and Infrastructure Development, Việt Nam General Association of Construction, Việt Nam needs to have clear, synchronous and unified environmental standards to require all stakeholders to fulfill certain obligations. Green drainage orientations should be included in the development of the Law on Water Supply and Drainage.

It is necessary to develop mechanisms and policies to develop green and smart infrastructure systems and comprehensively review, adjust and supplement standards on urban planning, technical infrastructure works as well as planning related to green infrastructure or design standards for green infrastructure works.

He proposed expanding the pilot programme on applying the sustainable drainage model, sponge cities and replicating nature-based solutions to develop resilient urban areas. VNS