Early saltwater intrusion threatens yet another Mekong Delta crisis

By Hoang Nam   December 16, 2019 | 06:03 am PT
With saltwater intruding deep and earlier than expected, people living in the Mekong Delta face a crippling freshwater shortage.

One morning in mid December Le Minh Hieu of Hung Khanh Trung B Commune in Ben Tre Province's Cho Lach District went to a canal behind his house with a worried face. He got some water from it and tested it using a salinity meter: the level read 2.0 parts per thousand (ppt).

"Plants with low salinity tolerance such as the yellow mai flower (Ochna integerrima), durian, mangosteen, and rambutan can only be irrigated with water with salinity of less than 0.5 ppt," the 40-year-old said.

His family has a 3,000- square-meter farm on which durian and yellow mai flowers are grown.

A salt water filter costs VND80 million (around $3,400) that can purify one m3 in four hours. Photo by VnExpress/Hoang Nam.

A saltwater filter that costs VND80 million ($3,450) can desalinate one cubic meter in four hours. Photo by VnExpress/Hoang Nam.

Hieu's is one of thousands of families in Ben Tre Province who faced a crisis of water shortage in 2016. After a prolonged drought and intrusion of water upriver from the sea, there was no freshwater for humans or cattle.

When they ran out of stored freshwater, he and many others in the neighborhood had to travel dozens of kilometers to buy water for VND100,000 ($4.3) a cubic meter for use at home, cattle to drink and watering plants that were withering and dying.

Ben Tre's Tan Trung Hamlet, which used to be known for its immense green of rambutan, durian and mangosteen plants, had become lifeless. Every affected household lost tens of millions to billions of Vietnamese dong (VND1 billion = $43,000) and began cutting down those plants and switching to ornamental plants.

"I and many people still owe the bank lots of money because of the water shortage then," Hieu said.

Around 600,000 households in Ben Tre and several other provinces in the Mekong Delta suffered from the lack of freshwater. Besides, 160,000 hectares of land were affected by saltwater, causing more than VND5.5 trillion ($237 million) in losses.

After paying a high price that time Hieu recently dug two ponds that can store 100 cubic meters of water for use when seawater flows upriver, usually starting after the Lunar New Year holiday, Tet, between mid-January and mid-February.

Hieu said fruit trees could take up to three years to recover and yield fruits again after surviving a water shortage.

But not long after his trees recovered and fruited Hieu and others in the commune discovered dead fish floating in the Co Chien River just five kilometers away as salinity levels surged to 8 ppt, two times the 2016 drought season.

Since his plants need a lot of water and there was no time to store freshwater since the saltwater came very early, he had to hire a mechanic for VND80 million ($3,400) to install a filter that can desalinate one cubic meter in four hours.

"Even at full capacity, only half the irrigation water required for a typical day gets purified. But you have to use that volume to hold out for the whole saline intrusion period. There is no other way," Hieu added.

The Ministry of Agriculture and Rural Development in September warned that drought and saltwater intrusion would come to 13 provinces in the delta several months earlier in 2020. 

It said the seawater could intrude 35-110 km inland this time, slightly deeper than in 2016, and affect 100,000 hectares of land under winter-spring rice. Some 50,000 households would face the risk of water shortage with Long An, Tien Giang and Ben Tre provinces expected to be the worst hit, the ministry added.

But only three months after the warning did drought and saltwater intrusion come. 

Dang Van Dung, chairman of the Hung Khanh Trung B Farmers Association, said the commune had not yet installed a closed saline prevention system to keep out seawater when the intrusion occurred suddenly since the area that the ministry listed as "at risk" is 60 kilometers away.

Ten kilometers away from Hung Khanh Trung B, people growing chrysanthemum morifolium have been worried sick for the past few days. Locals there installed the saline prevention system in time, but despite that seawater is entering irrigation and drainage canals in some places.

Huynh Van Linh pumps canal water into his field. Photo by VnExpress/Hoang Nam.

Huynh Van Linh pumps water from a canal into his field. Photo by VnExpress/Hoang Nam.

Huynh Van Linh, 21, connected his irrigation system to a canal to pump water into his fields where he has nearly 6,000 pots of chrysanthemum morifolium flowers.

"The water in the canal is still salty, but the salinity level is still low. So I took advantage of it to pump some water for storage for the next few days, afraid that it would become saltier later on," he said.

Phan Thi Be, 43, a neighbour who is growing 10,000 pots of chrysanthemum flowers, has a 10-cubic-meter cement tank, but with not much water left in it, she feared after another two days she would have to buy water.

"The chrysanthemum is in the flowering season. So I do not dare use the canal water, and have to buy water."

Locals had been expecting a good chrysanthemum season because of the weather, but due to the early arrival of the saltwater they can only water the flowers moderately.

Phan Thi Be waters her plants mannually with her back-up fresh water. Photo by VnExpress/Hoang Nam.

Phan Thi Be waters her plants manually using stored water. Photo by VnExpress/Hoang Nam.

Bui Thanh Liem, head of Cho Lach District's division of agriculture and rural development, said 13,000 households in the district farm 600 hectares of trees and flowers for the Lunar New Year, and most of the ornamental flowers are about to be harvested.

"Saline intrusion happened early and deep, reaching most of our communes, posing a risk of a flower shortage during Tet."

The Ben Tre Department of Agriculture has said that if the salinity persists, it will transport water for irrigation and look into scientific and technical methods to increase plants' tolerance to salinity.

The Tien Giang Province People's Committee recently held an emergency meeting to discuss solutions to the saltwater intrusion, which threatens 60,000 hectares of winter-spring rice, 10,000 hectares of vegetables and 80,000 hectares of orchards.

Authorities have urged people to store freshwater, assuring that in an emergency they will install water tanks and quickly drill large wells.

According to the National Center for Hydro-Meteorological Forecasting, between June and October rainfall in the upstream area of the Mekong River was 35-40 percent or about 0.4-0.7 m lower than the average. The mid and lower regions received normal average rainfall.

The forecast from now to February is for the Mekong to flow at a level 30-45 percent lower than normal.

The construction of massive hydroelectric dams on the Mekong is causing water shortages downstream. The overexploitation of groundwater causes land subsidence, allowing seawater to enter faster.

Many environmentalists think that, instead of trying to set right the problem, the Mekong Delta should identify areas where saltwater would be used, considering it a natural resource.

Recently Ben Tre Province has launched a VND6 trillion ($259 million) water management project. Eight saltwater prevention gates and pumping stations will be built in various districts and Ben Tre Town, the province's capital. Its goal is to generate freshwater and control salinity on more than 200,000 hectares, which will be used to irrigate about 90 percent of its agricultural land.

The project will be launched next year and will run until 2025.

But for the moment people in Cho Lach flower village carry cans, buckets and plastic containers to buy and store fresh water. Small barges normally used to carry sand are now being used to bring water from 30-40 km away for sale.

"I hope rains will come soon so that people will no longer suffer," Hieu said.

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