Even if China releases water from its hydropower dams on the Mekong River, it might not reach the Mekong Delta in Vietnam, experts warn.
Releasing water is a task China has to do periodically as its dams cannot keep holding back water, and given the increasing level of ice melt that raises sea level, it is a must for China to save its land from salt intrusion, Le Anh Tuan, deputy head of the Climate Change Institute at Can Tho University, said.
At the same time, as the river section of the Mekong from China, where it is called Lancang, to Thailand and Laos is running dry due to a severe lack of rainfall, releasing water is China’s only option to keep waterway traffic and trade going, he said.
Tuan was speculating about the reasons for China’s move, which was announced by Foreign Minister Wang Yi on February 20 at the fifth Lancang-Mekong Cooperation Foreign Ministers’ Meeting in Vientiane, Laos.
Yi said China would help its downstream neighbors cope with a prolonged drought by releasing more water from its dams on the Mekong River, adding it would also consider sharing hydrological information in future.
The drought has severely hurt farming and fishing in Laos, Thailand, Cambodia, Myanmar, and Vietnam, and many have said China’s dams are to blame along with climate change.
The Mekong River flows 4,880 km through six countries, 2,130 km in China. Of the 19 hydropower projects it plans on the Mekong, China has completed 11.
China too suffered from drought but has overcome its difficulty and increased water release in the river to help downstream countries cope, Yi said.
But Tuan said, “The water released from China’s dams in the upstream portion of the Mekong River will hardly make it to the Mekong Delta” because the outflow of 850 cubic meters per second is too little.
The water would be consumed in Thailand and Laos before it reaches the delta, he said.
Southern Vietnam is a few months into the dry season, which normally lasts until late April.
“In 2016, when the region was hit by the worst drought and salinity ever, China released water at a rate of 2,100 cubic meters per second, yet the water did not reach the region,” Tuan pointed out.
Given the current lack of water in the delta, China needs to release 2,500 cubic meters so that the region could be flooded, he said.
But even that would come too late, he said, explaining it would take three or four weeks for the delta to be fully watered even if China releases the water right now, and by then the paddy crop would have died.
Ky Quang Vinh, former chief of the climate change working office of Can Tho City, said China’s move mainly serves to mitigate its own drought.
“With such a small volume of water released … there is no way it can reach the Mekong Delta, which is 3,000 km (1,864 miles) away.”
The Mekong Delta is Vietnam’s most fertile region, rice granary and aquaculture hub.
But to perform those roles, the region needs the annual flooding, which has for generations begun in late July or early August and lasted until November, bringing extraordinary fertility in the form of silt it deposits.
But in recent years the flooding has not come regularly. Late rainfall during some years has exacerbated the situation.
The Ministry of Agriculture and Rural Development said last month the rainy season arrived late last year and was shorter than usual, with rainfall 8 percent lower than normal at 1,240 mm.
Water levels in the Mekong’s sections in the delta have decreased rapidly since the dry season began in late November and are currently 2.33 meters lower than in previous years, it said.
It is expected that the water level in the Kratie station in Cambodia will be 35 percent lower than in previous years in the first two months of 2020 and storage in Lake Tonle Sap, the largest freshwater body in Southeast Asia, is now at 5.1 billion cubic meters, 15.7 billion cubic meters less than normal.
The lack of water in rivers and canals has also allowed seawater to enter deep into the Mekong Delta.
According to the National Center for Hydro-Meteorological Forecasting, salinity has risen to up to four grams per liter 40-90 kilometers inland in all branches of the Mekong River.
Drought and salinity have affected 30,000 hectares of crops in the delta so far, or 7.3 percent of the 2016 figure, when 600,000 people did not have access to freshwater and 160,000 hectares of land were affected by saltwater, causing losses of VND5.5 trillion ($237 million).