Salinity arrives sooner than expected in Mekong Delta

Locals in Ben Tre Province are storing freshwater as saltwater intrudes into canals and rivers at levels higher than seen in previous years.

Last weekend, Vo Thi Ngoc Anh, 50, a resident in Binh Dai District of Ben Tre, switched to bottled water for cooking instead of using tap water.

« The running water has been tasting salty for two weeks now and I could not use it for cooking, » she said.

The water plant in Long Dinh Commune, where Anh lives, gets its water from branches of the Mekong River for processing and this year, salt intrusion arrived sooner than expected.

She said her family has also stored more than 10 cubic meters of rainwater for family use in addition to buying bottled water.

Pham Van Tri, 65, a resident of Giao Long Commune of Chau Thanh District, some 10 km away, has tanks and containers ready to store freshwater.

He intends to store 15 cubic meters in tanks and containers and 25 cubic meters in a water storage bag he has just bought for VND3 million (US$127).

Tri said every year it takes until late January or early February for saltwater to arrive, but the situation has been different this year.

Dang Hoang Lam, director of Ben Tre’s meteorological station, confirmed on Sunday that saltwater has intruded into the province sooner and deeper compared to previous years.

A week ago, saltwater was measured at around 25-54km away from the estuaries of the Ham Luong, Cua Dai and Co Chien rivers, which are all branches of the Mekong, with salinity levels ranging from 0.1 to 2.6 parts per thousand (ppt), or grams per kilogram of water.

In the coming days, saltwater is predicted to intrude deeper and at a higher level, reaching around 4 ppt, he said.

Salinity above one gram is considered unpalatable and levels of above two are unsafe for most crops.

Nguyen Huu Thien, an independent expert on the Mekong Delta’s ecology, said the increase of salt intrusion in rivers in Ben Tre Province is a result of the northeast monsoon winds.

He said the monsoon has grown stronger in recent days pushing saltwater into the rivers.

However, during the 2023 dry season, which normally starts in late November and lasts until early May, the southern region will not experience drought and salinity at levels as fierce as in previous years, the expert said.

This is because the La Nina phenomenon will last until January, causing unseasonal rains from now until late January.

Thien also cited data of the Mekong Dam Monitor (MDM), the near-real time tracking of dam operations and river flows by the U.S. Stimson Center, to say that 45 dams along the Mekong’s upstream will store water at a level of 74% of their capacity and when they discharge water to generate electricity, the downstream area will also benefit.

During the 2020 dry season, the delta, home to 20 million people, was hit by the worst drought ever which caused historic levels of salinity in its rivers.

By mid-March that year, seawater had intruded 50-110 km into major rivers and all branches of the Mekong, two to eight kilometers more than in 2016 when the region suffered the worst drought in a century.

In all, the lack of freshwater damaged 41,900 hectares of rice and 6,650 hectares of fruit orchards, while 96,000 families struggled to obtain water for their daily needs that year.

The situation was not as severe last year, but experts have been warning that climate change and the building of dams upstream of the Mekong River could worsen drought and salinity in the region.

By Hoang Nam – VnExpress.net – December 26, 2022