Mekong Delta braces for severe drought, river salinity

The Mekong Delta region is scrambling to protect millions of hectares of crops from drought and saltwater intrusion that could be as severe as in 2016 and 2020.

At the end of September Nguyen Van Can, 50, of Hoa Luu Commune in Hau Giang Province’s Long My District prepared to sow winter-spring rice in his three-hectare farm.

He said he was sowing earlier than usual fearing a possible drought once the rainy season ends in October. The dry season in southern Vietnam lasts from November to April.

“Land in this area is at risk of salinity from the sea and with the forecast that the rainy season will end early this year, farmers have started the winter-spring crop earlier than normal.”

Tran Ba Hoang, director of the Southern Institute of Water Resources Research, said at a seminar in Can Tho City on September 14 that the total rainfall in the delta this year is forecast to be around 1,350mm, or 13% lower than normal.

The Southern Regional Hydrometeorological Station said the flow in the dry season from the Mekong’s upstream areas would be 20 – 25% lower than normal.

In Hau Giang Province, 12,000 ha of winter-spring rice and more than 18,500 ha of fruit orchards are likely to be affected by saltwater intrusion up rivers.

In Ben Tre Province, Vo Van Duc, 64, of Chau Thanh District is closely following the rain and drought forecasts to protect his durian farm.

“After hearing that this year’s saltwater intrusion will last longer than normal, my family has drilled another well to get water,” he said.

According to the province Department of Agriculture and Rural Development, almost all locals have made preparations to store water for both household use and irrigation, and dug canals to lead water from rivers into their farms after learning from the shortages of 2016 and 2020.

In the 2020 dry season the delta, home to 12 provinces and Can Tho City, was hit by the worst drought ever that caused historic levels of salinity in its rivers as water flowed inland from the sea.

The rainy season arrived late in 2019 and was shorter than usual, resulting in 8% less rainfall than normal at 1,240 millimeters, according to the Ministry of Agriculture and Rural Development.

A series of upstream dams in China is seen as preventing the natural flow of water down the Mekong, while the sea level rise and gradual subsidence of southern Vietnam are also blamed for saltwater intrusion into the delta.

By mid-March 2020 seawater had intruded 50-110 kilometers into all branches of the Mekong, two to eight kilometers more than in 2016 when the region suffered the worst drought in a century.

It damaged 41,900 ha of rice and 6,650 ha of fruit orchards, while 96,000 families struggled to obtain water for their daily needs.

During the 2016 drought 160,000 ha of paddy were damaged as farmers lost an estimated 800,000 tons of rice. The losses were worth VND5.5 trillion (US$237 million).

In the 2023-24 winter-spring rice crop, farmers will plant 1.47 million hectares and expect to harvest 10.6 million tons.

This year, with El Nino returning, experts have warned of less rainfall and more drought in Vietnam.

The Ministry of Agriculture and Rural Development has said if the drought and saltwater intrusion are as severe as in 2016, the delta could lack the water to irrigate 60,000 ha of rice and 43,000 ha of fruits in Long An, Tien Giang, Ben Tre, Tra Vinh, and Soc Trang provinces.

Tran Hoang Nhat Nam, deputy director of the Tien Giang Province Department of Agriculture and Rural Development, said six sluice gates have been built along the Tien River, a Mekong tributary flowing through the province, to keep out salinity.

They will help store enough water to irrigate 128,000 ha (316,300 acres) of lands and provide 1.1 million people in Tien Giang and neighboring Long An Province with drinking water.

Le Tu Do, director of the Mekong Delta branch of the Southern Irrigation Management One Member Ltd., which operates the region’s biggest irrigation system in Kien Giang, said the company is keeping a close eye on salinity levels inside and outside the system to make timely adjustments.

The system, on the Cai Lon and Cai Be rivers, was completed last year at a cost of VND3.3 trillion ($142.2 million)

The system, funded by government bonds, irrigates 384,000 ha of lands in Kien Giang, Hau Giang, Ca Mau and Bac Lieu provinces.

By An Binh & Hoang Nam – VnExpress.net – October 2, 2023