Truong Xuan Ty, deputy director of the Danang Department of Agriculture and Environment, said the 2026 El Nino could be as strong as or stronger than those of 2015-2016 and 2019-2020, citing national meteorological assessments.
Monitoring data from June to mid-October showed that flows in most rivers and streams in the Vu Gia-Thu Bon basin were 10-33 per cent below long-term averages.
According to the Central Regional Hydrometeorological Centre, flows over the past year were 66 per cent below average on the Vu Gia River at Thanh My station, but 6 per cent above average on the Thu Bon River at Nong Son station.
From October 2026 to September 2027, flows on the Vu Gia River could remain 60-75 per cent below normal, while those on the Thu Bon River are expected to be close to average.
Ty said the unusually low river flows were the main reason hydropower reservoirs in the upper Vu Gia-Thu Bon basin were experiencing water shortages in the middle of the 2026 rainy season.
Based on El Nino forecasts and assessments by the Ministry of Agriculture and Environment, Danang faces two possible scenarios, classified as high risk and very high risk.
Both scenarios indicate a high to very high risk of water shortages and saltwater intrusion affecting surface water sources used by treatment plants.
Urban water supplies depend heavily on rivers and upstream reservoir operations, leaving households vulnerable if water levels continue to fall.
Agricultural production could also face drought, particularly during the 2027 summer-autumn crop.
"Under the very high-risk scenario, many reservoirs may fail to store sufficient water, with shortages potentially lasting until the start of the 2027 rainy season," Ty said.
He warned that a delayed rainy season could further slow reservoir replenishment and threaten hydropower generation during periods of peak electricity demand.
To address the risks, Danang is introducing measures to improve water storage, reservoir management and water use, aiming to safeguard domestic supplies, agricultural production and energy security.
The municipal Department of Agriculture and Environment has proposed urgent instructions requiring operators of six hydropower reservoirs to prepare flexible operating plans through December 31.
The reservoirs include A Vuong, Song Bung 4, Dak Mi 4A, Song Tranh 2, Khe Dien and the first stage of Song Con 2.
Operators will be required to prioritise water storage to maintain supplies for households and production activities downstream.
The department has also submitted an emergency response plan to the municipal People's Committee to address potential El Nino-related water shortages and secure domestic water supplies in 2027.
Authorities are developing additional measures to prevent drought, water shortages and saltwater intrusion affecting agriculture and households next year.
Officials said early preparations were essential to minimise the risks rather than waiting until shortages occur.
