Last Saturday, Vinh recorded nearly 400 millimeters of rain in six hours, surpassing the area’s September daily rainfall record of 387.9 mm set on September 10, 1985, according to data from the national weather agency.

Water levels in the moat in Thanh Vinh Ward rose to street level before receding, leaving behind piles of plastic bags, foam boxes, bottles, and other debris trapped at drainage outlets.

By Monday morning, thick layers of trash lined several sections of the moat, creating an unsightly scene and foul odors.

Residents called on local authorities to step up cleanup efforts and improve waste management to prevent similar problems during future downpours.

Tran The Hung, a resident living nearby, said the accumulation of garbage not only spoiled the landscape but also created unpleasant smells.

“If the trash is not removed quickly, the sun will intensify the odor, affecting households around the moat,” he said.

Dinh Nho Tai, vice-chairman of the Thanh Vinh Ward People's Committee, told Tuoi Tre (Youth) online newspaper that the local authorities had previously carried out a project to renovate the moat, including dredging, building embankments, installing a wastewater collection and dilution system, and improving the surrounding landscape.

However, pollution has not been completely resolved.

He explained that pollution stems from untreated household wastewater discharged directly into the moat, combined with an overloaded drainage system.

Household waste, plastic bags and foam containers are also sometimes dumped directly into the moat or washed in from other areas after heavy rain, such as the historic downpour last Saturday.

He said workers will be mobilized to collect and remove the trapped waste.

The moat, part of the Vinh ancient citadel built in 1831 under the Nguyen Dynasty, is about three meters deep and 28 meters wide.

In 2016, authorities invested nearly VND140 billion (US$5.3 million) from World Bank loans to dredge, reinforce embankments, install wastewater collection systems, and improve landscaping.

The project was completed in 2018, but pollution has since returned, especially after heavy rains.

The Vinh ancient citadel, recognized as a national historic site in 1998, retains three gates and sections of its moat.