Salinsation and drought problems in the Mekong Delta

Salinisation, Drought Bring Worries to Mekong Delta
By Tran Dinh Thanh Lam
Source: IPS News

MEKONG DELTA, Vietnam, Mar 18, 2010 (IPS) - He has worked this land for half of 64 years and is known among his fellow farmers in Kien Giang province here in the Mekong Delta as ‘lao nong’, or the old master of rice.

But even a highly experienced and hardworking rice farmer like Nguyen Tu is finding it a great challenge to grow crops in the Mekong Delta these days.

"I spent a whole day and whole night pumping water into the rice field, but the little amount of freshwater I got could hardly wash the five hectares of rice immersed in saltwater," Tu tells IPS.

"Every year, I have to wash off saltwater (from our field), but things become worse year after year," he adds, complaining about the build-up of salt on the soil as a result of the intrusion of saline water into the rich river area. "Last year, I got more freshwater for a smaller contaminated area."

Like other South-east Asian countries, Vietnam has a wet and a dry season. In the last decade or so, the dry season seems to have been coming earlier each year – and then staying far longer.

This has spelled disaster for farmers in the six Vietnamese provinces in the Mekong Delta, where saltwater from the South China Sea can intrude as far as 30 kilometres inland during the dry period. Tu is not sure his winter-spring crops can survive the prolonged dry spell as these are being soaked too long in "so much salt", which destroys soil fertility.

Experts say that rice can grow in water that contains no more than a two- thousandth part of salt, but Kien Giang already has a salinisation of twice that level at present.

The Mekong Delta is Vietnam’s ricebowl, producing half of its annual rice output. Majority of the country’s fruit crops also come from this region. Then again, that was before the changes in weather patterns wreaked havoc on the crops here.

"Weather changes have made a clear impact," Pham Van Du, deputy director of the Department of Agriculture Cultivation of Can Tho, Hau Giang told ‘Vietnam News’ recently. "This means the meteorological conditions of the Lower Mekong have changed slightly; drought becomes severe while water scarcer. This results in more saline water encroaching all parts of the Lower Mekong."

The dry season this year alone came some four months in advance. According to the Institute of Irrigation, there was even saltwater in areas situated from 50 to 70 km off the sea as early as the third week of January.

By February, which used be a month when people still enjoyed cool weather, several "summer" days had many Vietnamese running for fans as temperatures rose to as much as 37 degrees.

There has also been less precipitation compared to previous years. During February, Hanoi had just 60 percent of rain compared to the same period last year, while the Central Highlands and south-west provinces have received no rainfall at all.

Here in the Mekong Delta, no rain has fallen for months now, reducing the volume of underground water. This has not helped the serious salinisation of soil that is now threatening 620,000 hectares of winter-spring crops, based on data released in a workshop presided over by Minister of Agriculture and Rural Development Cao Duc Phat on Mar. 12, at the southern province of Soc Trang.

The Southern Institute for Irrigation also says that the dry spell, shortage of water, and salinisation will worsen by April and May.

Many Mekong Delta farmers, however, say that Mother Nature is not solely to blame for their predicament. They say dams – especially those built by China – on the Mekong River upstream have caused lower water levels downstream, along with reduced river running speeds and altered ecosystems.

Officially, pointing a finger at China is not encouraged in Vietnam, and even experts here usually choose to remain silent on such matters. But recently, Vietnamese experts quoted the online VietnamNet considered the matter on record, although they were also careful to note that other countries, such as Laos, Cambodia, and Thailand, had built dams on the river or had plans for such on the Mekong mainstream as well.

Prof Ngo Dinh Tuan, chairman of the Institute for South-east Asian Water Resources and Environment’s Scientific Council said that "the first impact" of Chinese dams built for the production of electricity "would be a remarkable reduction of aquatic resources and the volume of alluvium in the delta, resulting in landslides to balance the alluvial volume. It would be very dangerous for people who live in the lower section."

"If China builds dams to transfer water from the Mekong River to the northern region," he also said, "it would be very dangerous because the water volume going down to the lower section would be reduced considerably."

Deputy director of the national weather service Le Thanh Hai meanwhile told the ‘Tuoi Tre’ newspaper that while the primary cause of the drought is the El Nino phenomenon, "the hydropower plants made extra effort to store up water behind the dams when rainfall proved inadequate to supply these". "When they produce power," he added, "water is released from the dams but not enough to restore the flow in the rivers to normal levels."

Chinese officials who have heard worse from irate Thai farmers have said that the drastic drop in the Mekong has nothing to do with China retaining water upstream. To prove this, China recently invited lower Mekong countries to visit its Jinghong dam to observe how it is being run and why it could not cause any harm to downstream countries.

Vietnam has received and accepted the invitation, said Le Duc Trung, chief executive officer of Vietnam’s Mekong River Commission Office who will lead the country’s delegation to China.

In an interview with ‘Tuoi Tre’ last week, Trung also said that he plans to ask China to strengthen cooperation with downstream countries by supplying more information on its dams, especially documents regarding their resource management data and guidelines. But the date for the visit has yet to be set, Trung said.

On Wednesday, though, Trung used sharper words in an interview with ‘Saigon Tiep Thi’ newspaper. "China could no longer hide the information (about the dams). No country could play alone on its playground, close off information to the outside world."

Earlier this year, Mekong Rice Institute Director Le Van Banh told Radio Free Asia that it was crucial for all Mekong countries to work together to devise methods of sustainable use for the water source. "If each country takes its own action for its own benefits, then all will suffer and the Mekong Delta will endure more damage," he said.

Banh is well placed to comment on selfish behaviour, having witnessed such in the Mekong Delta.

To help farmers make use of the annual cycle of flooding and salinisation, local experts had been promoting a new method of cultivation: alternating the culture of shrimp with that of rice.

During the winter-spring season from January-June, farmers would use saltwater to raise shrimps in their fields. Once the rainy season in June to December came, rainwater would "wash" the fields to make them suitable for rice planting.

A system of dams was built to store floodwater and push back saltwater during the dry season. Unfortunately, some greedy farmers destroyed several of these dams to drive the saline water to their shrimp farms. With the dam system damaged, saltwater has thus now submerged the crops of rice farmers like Nguyen Tu. (END)