On 19/8, the Department of Meteorology and Hydrology announced that ENSO—an abnormal warming and cooling climate phenomenon in the Pacific Ocean—has transitioned to El Nino status. This phenomenon is forecast to maintain strong to very strong intensity in the coming months.

From September to November 2026, there is a 100% probability of El Nino being strong to very strong, with a 93% chance of reaching very strong intensity. This probability increases to 95% for a very strong El Nino from October to December.

Ta Mon irrigation reservoir, Lam Dong, cracked due to drought in 2020. Photo: Viet Quoc

The Ministry of Agriculture and Environment predicts that El Nino will almost certainly lead to a deficit in rainfall and water resources. Widespread drought and saltwater intrusion are expected to begin early in the dry season, around November 2026. In the Mekong Delta, South Central Highlands, and Southeast Region, these conditions could persist until May 2027. The North Central and South Central Coastal Regions may experience impacts until July-August 2027.

Despite water resources for agricultural production being largely secured since the beginning of the year, with drought and saltwater intrusion affecting only localized areas, rainfall has generally been below average. Furthermore, many irrigation reservoirs are currently only at 35-50% of their design capacity. The Northern Region, currently in the middle of the rainy season, has reservoirs reaching about 84% of their design capacity.

The Department of Irrigation Works Management, under the Ministry of Agriculture and Environment, assesses that under a high-risk scenario, water flow to the Mekong Delta could be 5-10% lower than the multi-year average. Saltwater intrusion of 4 g/l at the Mekong River estuaries could penetrate 45-60 km inland, and approximately 90-100 km at the Vam Co river mouths.

This scenario could impact about 64,000 ha of 2026-2027 winter-spring rice, 80,000 ha of rice and shrimp farms, and 19,000 ha of fruit trees. If water levels are 15-20% below the multi-year average, saltwater intrusion could be comparable to the 2015-2016 dry season. The 4 g/l saltwater boundary might extend 50-70 km inland at the Mekong River estuaries and 110-130 km at Vam Co. In this event, approximately 85,800 ha of winter-spring rice, 120,000 ha of rice and shrimp farms, and 45,000 ha of fruit trees are at risk.

Saltwater intrusion caused rice deaths in Can Tho in 2024. Photo: Huy Phong

In the North Central and South Central Coastal Regions, risks largely depend on this year's rainy season rainfall and the water storage capacity of reservoirs. A high-risk scenario could affect approximately 12,000-25,000 ha of crops during the 2026-2027 winter-spring season. If rainfall deficits reach 20-40%, reservoirs only store 70-80% of their design capacity, and temperatures are 1-2 degrees C higher than average, the affected area could increase to 25,000-50,000 ha.

By the 2027 summer-autumn season, about 58,000-85,000 ha could be affected under a high-risk scenario, and 90,000-120,000 ha under a very high-risk scenario. These impacts would primarily occur in areas outside irrigation systems or those with small-scale infrastructure.

In the South Central Highlands and Southeast Region, over 70% of cultivated land lies outside irrigation systems, making it vulnerable to an early end of the rainy season. Under a very high-risk scenario, approximately 135,000-190,000 ha, mainly perennial crops, could be affected during the peak dry season.

Beyond agricultural production, rural domestic water supply also faces potential shortages. A very high-risk scenario indicates that around 107,000 households in the Mekong Delta, 92,830 households in the North Central and South Central Coastal Regions, and 54,740 households in the South Central Highlands and Southeast Region could be impacted.

Saltwater intrusion in Ca Mau in 2024. Photo: Thanh Tung

Given these risks, the Ministry of Agriculture and Environment has implemented response measures since the beginning of the year. Yesterday, it further instructed localities to closely monitor El Nino forecasts, identify production areas at risk of water scarcity, and adjust cropping seasons, or reduce and halt production in areas with insufficient water resources.

Localities in the Mekong Delta are advised to arrange cropping seasons starting from summer-autumn 2026 to bring forward the winter-spring crop, thereby avoiding peak saltwater intrusion periods. Central provinces are urged to ensure the safety of irrigation infrastructure and enhance reservoir water storage capacity.

The Department of Irrigation Works Management and Construction plans to develop a framework for directing and managing drought, water scarcity, and saltwater intrusion prevention for the 2026-2027 dry season. It will also continue updating scenarios and providing information to localities to facilitate suitable production planning.

The Ministry also proposed that localities in the North Central, South Central, Southeast, and Mekong Delta regions activate responses according to a very high-risk scenario. Additionally, it recommended organizing a conference to implement drought, water scarcity, and saltwater intrusion prevention solutions in late September or early October 2026.

Gia Chinh