The Mekong Delta, the nation’s agriculture and aquaculture hubs, should expect the worst during February 10-15, February 26-March 2, March 12-16 and 25-29, and April 14-19 and 24-28 before the saltwater gradually retreats.

During the last dry season, which normally lasts from November to April in southern Vietnam, saline levels of up to six grams per liter were found in some areas.

Salinity of one to four grams was found 50 km (31 miles) upstream on average, and up to 130 km, in all the tributaries of the Mekong in the delta.

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

A farmer in Tam Binh Commune in Tien Giang’s Cai Lay District measures the salinity
level in local water, which has exceeded 5 grams per liter, March 2020.
Photo by VnExpress/Huu Khoa.

For the situation last year in the delta, experts have been blaming the El Nino phenomenon and Chinese dams.

El Nino caused scanty rainfall in southern Vietnam last year while upstream Chinese dams held back water and sediments that traditionally fertilize downstream agricultural lands, the experts said.

The Mekong flows 4,880 km through six countries, 2,130 km in China. Of the 19 hydropower projects it plans along the river, it has completed 11.