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Dams, Sand, Rice: The Life and Possible Death of the Mekong Delta

What would Vietnam be without the Mekong Delta?

Envisioning such a reality is difficult, but it is entirely possible that this will come to pass, albeit long after anyone reading this in 2020 is dead.

The delta is Vietnam’s most vital agricultural region, producing 50% of the country’s rice, including almost all rice for export, 65% of aquaculture products and 70% of fruit, according to government figures. It is also home to over 20 million people.

Fed by the Mekong River, which tumbles down nearly 15,000 feet of elevation on its way from the vertiginous Tibetan Plateau to Vietnam, the delta is one of the world’s great natural systems. Over the last 6,000 years, sediment carried by the river created the delta, with land pushing into the sea at an average rate of 16 meters a year. The region is known as Cửu Long in Vietnamese, or Nine Dragons, for the nine major river distributaries that flow through it.

The Mekong sustains the delta to this day, but the delicate natural processes of this relationship have been disrupted, and nothing less than the very survival of Cửu Long is at stake.

An early morning ferry crossing in the delta. Photo by Michael Tatarski.

To anyone paying even passing attention to Southeast Asia news, this shouldn’t come as a shock, but the most critical threats are not the ones getting the most attention. Upstream dams and climate change are generally portrayed as the two killers of the delta, with dams holding back sediment and water flow while the sea crawls deeper into the delta every year.

These problems are very real, but the situation is much more interconnected, and much of the danger comes from within Vietnam.

Beyond the dams

“The complex web of issues can be categorized into three groups,” says Nguyen Huu Thien, an independent ecologist from Can Tho who has studied the delta for his entire life. “The usual suspect of climate change, of course, but also upstream hydropower and internal development errors.” Sea level rise, which is what climate change generally refers to in relation to the delta, is happening, but slowly. “Right now it’s only 3 millimeters per year, a gradual process,” Thien explains. “It’s happening, but a lot of people use the worst scenario and forget to tell the public that the time horizon is to the end of the century.”

Subsidence, which is the sinking of land, is happening at a much faster rate, in some cases centimeters (tens of millimeters) per year, and that is rooted in the “internal development errors” mentioned above. “We are subsiding because we are using a lot of groundwater, and the irony is that although we are living in one of the biggest river basins on the planet, where we have an abundance of freshwater, the surface water cannot be used [due to pollution], so we resort to extracting water from under our feet.”

Sunset over a branch of the Mekong River. Photo by Michael Tatarski.

When combined with sand mining, the impact of this groundwater extraction is devastating.

“At the moment there are two main natural resources that are being over-extracted in the delta, sand and groundwater,” says Philip Minderhoud, a physical geographer at Utrecht University and the Research Institute Deltares in the Netherlands who has conducted extensive research on the region. “These two very basic commodities are everywhere around you, so people don’t really value them, but in the end they are very valuable, if you over-consume them you get a lot of problems, and that is what is now driving most of the environmental change in the delta.”

Like Thien, Minderhoud is well aware of the long-term threats posed by climate change, which includes abnormal rainfall patterns and temperatures, in addition to sea level rise, but he doesn’t place it as the most pressing problem to confront. In fact, he undertook research with Sepehr Eslamia, a PhD candidate in coastal dynamics at Utrecht, to determine the current balance of damage between climate change and resource extraction.

“We estimated that maximum 10% of the ongoing saltwater intrusion is climate change-induced, while 90% is caused by anthropogenic impacts to the system, and a large part of that is locally in the delta,” Minderhoud shares.

In Thien’s view, subsidence is more of an immediate concern than rising seas: “The root cause is that we are polluting our rivers and canals with intensive agriculture, and worse is that our rivers and canals have lost their self-purification capacity because we have followed the rice-first policy.”

Verdant rice paddies outside Sa Dec. Photo by Michael Tatarski.

The rice problem

Rice may form the base of many of our favorite Vietnamese dishes, but modern-day production methods for the grain have wreaked havoc on the delta’s natural systems.

Up until the early 1980s, rice farmers in the region harvested one crop per year, and helped bring Vietnam back from the brink of famine following the ruinous American War. However, that eventually went too far. “In 1989 we began to export rice,” Thien explained. “We thought that was great, and we started to earn foreign currency, so we kept on increasing rice paddies, and once we had no more land, we moved to intensive farming of multiple crops.”

This enriched farmers and turned Vietnam into one of the world’s greatest rice producers, but the Mekong’s natural floods were erased through a combination of upstream development and irrigation and anti-flooding projects within Vietnam.

“So the floodplains were there to absorb floodwater, but we refused to allow floodwater into the plains, so it rushed into the ocean,” Thien said. “In the dry season now when the Mekong becomes weaker, we don’t have supplementary flow from the soil, so salinity intrudes further.”

Rice processing facilities in the delta. Photo by Michael Tatarski.

While not as visibly disruptive as immense hydropower dams (we couldn’t figure out how to illustrate saltwater intrusion for the top image), the ocean’s steady advance into the delta is an existential threat to the very farmers benefiting from rice production.

In February, the region’s largest freshwater reservoir, located in Ben Tre Province, started filling with saltwater, impacting the more than 200,000 people who rely on it for water. That same month, officials in Can Tho, which sits almost 100 kilometers away from the sea, detected high levels of salinity in the Hau River and nearby canals, threatening thousands of hectares of rice, flowers and vegetables. Just this week, people living in Ben Tre who have never dealt with saltwater intrusion before started noticing it in their water supply, forcing them to buy expensive water trucked in from elsewhere.

This creeping salinity works in a vicious cycle with land subsidence: the faster the ground sinks, the faster saltwater finds its way upstream.

Life next to the river. Photo by Michael Tatarski.

Sand and water extraction

The traditional method of confronting saltwater intrusion is infrastructure, but this creates problems of its own. “We protect the coast with dikes and sluice gates and that stops the influence of tidal water, so inland canals and rivers become slow-moving or stop, so there is no oxygen and the water receives a lot of chemicals which it can’t process,” Thien explains. “So the surface water becomes unpotable and we use groundwater. We’re sinking, but then we blame sea level rise.”

At the same time, sand mining causes erosion that aids saltwater’s journey upstream and washes entire houses into the river, a creeping disaster threatening Cambodia too. Dams factor into this equation as well, as they hold back sediment that would help to replenish riverbeds stripped by sand mining.

Sand mining and groundwater extraction can, in theory, be stopped — or at least slowed — by strong regulations and enforcement, but the first step is recognizing the problem.

“There’s a big economic perspective because right now this sand that’s being mined and the water being pumped up is free,” Minderhoud says. “It’s a great business model to extract something that is free and then make money off of it.”

To get a sense of just how dire things could become if sand mining and groundwater extraction continue unabated, it’s worth looking at visual projections from a January paper which Minderhoud co-wrote titled 'Groundwater extraction may drown mega-delta; projections of extraction-induced subsidence and elevation of the Mekong delta for the 21st century.'

The top row depicts a scenario in which groundwater extraction rates continue to grow, with blue regions sinking below sea level. The bottom row forecasts a reality in which groundwater extraction slows and natural systems recover. Figure via IOP Science.

These maps may call to mind the widely-discussed flooding maps from Climate Central published by The New York Times last October, which included an apocalyptic map of an almost completely submerged Mekong Delta at high tide by 2050.

Minderhoud’s research looks somewhat similar, but it is important to keep in mind that the blue in the above figure indicates land that is below sea level, not underwater, while also using more precise local data instead of global information. “You can still protect areas that are below sea level, but it becomes more difficult the more you sink,” he says. “Costs increase exponentially the more you are below sea level.”

Along with several colleagues, Minderhoud also found in a Nature paper published last year that the delta is actually much lower than previously assumed, with a mean elevation of roughly 0.8 meters above sea level, instead of the generally accepted figure of roughly 2.6 meters.

Meanwhile, sand mining volumes are now roughly equal to the amount of sediment that the Mekong transported to the delta annually before dams were built on it.

Is it too late?

While much of this is extremely worrying, nature is highly resilient, and the Mekong Delta’s natural balance has only been off-kilter for the blink of an eye in geological terms; 15 years, to be precise.

“Before 2005, for thousands of years the delta was built by sediment deposition,” Thien says. “In the past, we had sediment accretion and erosion, but accretion always prevailed. Starting in 2005, we started to have negative accretion, and the balance changed. At this rate, I think the delta might disappear altogether physically on the map within 200 years.”

That is a long ways off, however, and steps can be taken to avoid this fate.

“This calls for sustainable ways of managing your water and sediment in the delta,” Minderhoud says. “There is enough water available, maybe not throughout the year because there are droughts and saltwater intrusion, but it comes down to managing the water. Try to save your freshwater during the wet season, and then use it during the dry season.”  

The Vietnamese government, of course, is aware of the danger facing this highly critical region. On November 17, 2017, it released Resolution 120 “on Sustainable and Climate-Resilient Development of the Mekong Delta of Viet Nam.”

The resolution lays out targets for 2050 and 2100, and has been well-received by experts like Thien.

A bustling canal in Sa Dec. Photo by Michael Tatarski.

“It sets a wise strategic direction for the transformation of the delta’s development, though that can address internal development issues only,” he shares. “The major spirit of the resolution is to transform agriculture from production-focused to quality-focused, which will address a lot of issues.”

For example, by reducing the number of annual rice harvests, natural floodplains will begin to reform. “That will increase the resilience of the delta to salinity in the dry season, because when you temporarily store floodwaters in the floodplain, you have supplementary flow, and that will make the anti-salinity structures along the coast obsolete.”

Implementing Resolution 120 will be difficult, however, due to the number of stakeholders involved. “The prime minister assigned Resolution 120 to the Ministry of Resources and Environment to coordinate the involvement of different ministries,” says Nguyen Hong Quan, assistant director of the Center for Water Management and Climate Change.

“But one of the most important parts of this is the integrated Mekong Delta plan, which is now led by the Ministry of Investment and Planning. And then there’s the Ministry of Agriculture and Rural Development, which is another big stakeholder."

These ministries, Quan explains, make decisions at the central level, meaning they don’t always fit the granular context: “The local provincial governments should have more power and flexibility to adapt land use planning to local conditions, and to follow the farmer’s wishes. If they transfer requests from the central government to farms, it’s difficult.”

“There’s no one solution that fits all,” Minderhoud concurs. “Crops that use less water, more efficient irrigation, maybe salt-resistant crops, all of these measures are often locally suitable, but they have to be tailor-made to every location in the delta.”

The dams

Hanging over all of this, like knives slicing apart Cửu Long, are the upstream dams, a problem which Vietnam has little control over.

Pitched by developers as a way to power one of the world’s fastest-growing economic regions, dams have become a favored engine of development, especially in Laos. The downstream effect, most prominently in the Mekong Delta, which receives the cumulative impact of every one of these dams, is profound.

A map of mainstream Mekong River dams from 2017. Image via International Rivers.

“In terms of trapping sediment and sand and then causing erosion in the delta, it’s permanent and serious and cannot be reversed,” Thien states. “Fine sediment is not only the very material that built the delta over the last 6,000 years, but it’s also the source of natural fertilizer for agriculture and aquatic systems, especially coastal fisheries that depend on nutrients attached to the sediment.”

While the delta’s land produces a majority of numerous vital crops, its offshore reaches also contain key fisheries. According to Thien, the 700-kilometer-long coast makes up 50% of Vietnam’s annual fish catch.

“If in the future all of the planned Mekong River dams are built, 96% of sediment will be trapped, while 50% is already trapped by the cascade dams in China,” he adds. “If this happens, the coastal water will become transparent, while right now it’s chocolate-colored for 30 kilometers from shore.”

Sediment carried downstream also counteracts subsidence caused by sand mining, but this balance has tilted in the wrong direction, and will collapse as more dams are built.

Additionally, the loss of sediment would not only starve sea life of nutrients, but would also expose the delta to dangerous storms and waves, as sediment-filled water is heavier than open ocean water and absorbs wave energy. 

A Tet flower farm near Sa Dec. Photo by Michael Tatarski.

Brian Eyler is a Senior Fellow and Director of the Southeast Asia Program at the Stimson Center in Washington D.C. and author of The Last Days of the Mighty Mekong, which explores the death throes of one of the world’s greatest river systems. He argues that in order for the extreme threats facing the Mekong to be addressed, a new paradigm needs to be introduced.

“The typical discussion is that dams block fish, sediment and water flow,” Eyler says. “That doesn’t capture the dynamism of what’s happening in a fuller scope, which is that dams block and prevent flow of fish, second is climate change, which is above the river so we think about what’s going into the water and how it is impacting weather patterns and lengthening the dry season. Third is extraction, which brings in illegal fishing, sand mining and groundwater. Fourth is land use, which brings in farming practices as well as urban planning.”

Each of these, with the exception of dams, can be addressed within Vietnam, as discussed above, but these are trans-national problems as well. Stretches of the river upstream have faced particularly dire circumstances in recent months, with blue water signifying a deeply unhealthy river seen in Thailand.

“The system is really complex, and whether we’re at the point of no return, where the river’s ecological processes can no longer repair themselves, we’ll have to wait until next year to see and more research is done,” Eyler says. “But what we do know is that for each dam that goes up, and not just on the mainstream of the Mekong, but also on its tributaries, each has an incremental effect on the delta.”

One piece of good news amid this doom and gloom is that the construction of dams on the Mekong River itself has been slow, perhaps in part thanks to the Mekong River Commission (MRC), an inter-governmental organization which works with the governments of Cambodia, Laos, Thailand and Vietnam to try and sustainably manage the river.

“The MRC has no veto power and is based on consensus,” Eyler explains. “But what we can say about the MRC is that the whole discussion on mainstream dams started in the lower Mekong in the mid-1990s, and it’s now 2020 and only two dams have been completed out of the planned 11.”

Slices of life in the delta. Photos by Michael Tatarski.

Meanwhile, over 60 dams have been built on tributaries of the great river in Laos, and Vietnam is, bizarrely, involved in the proposed construction of the Luang Prabang dam through the state-owned PetroVietnam Power Corporation. This would be the third on the Mekong itself outside of China, and it greatly concerns Eyler.

“Resolution 120 looks very useful for turning the delta’s economy around, for allowing nature to run its course, to allow floods to happen,” he says. “As that is rolling out and Vietnamese ministries and development partners are getting involved, Vietnam is also moving forward with a mainstream dam that would undo any of the gains that Resolution 120 would bring forward. I’m kind of gobsmacked by the decision.”

In addition to the solutions proposed above by Thien and Minderhoud, Eyler suggests that Vietnam use the current drought to create future regional agreements that could help alleviate damage in the future.

“Vietnam needs to realize that the rules of the game can change with a crisis like this, and it can use the period of crisis to move some smart policies forward,” he says. “The dams in China and Laos are holding back a lot of water; China’s mainstream dams alone hold back 47 billion cubic meters of water, which can be used to relieve downstream drought.”

China recently announced that it would release some of this water to help downstream countries, though there is doubt whether Vietnam will see any benefit. This has been done before, but only on a case-by-case basis.

A produce market on the banks of a Mekong River branch. Photo by Michael Tatarski.

“There needs to be some sort of automatic mechanism for countries on the Mekong, China included, which returns the river to some kind of normal flow during the dry season, and those dams can help do that,” Eyler adds. “Vietnam, Thailand and Cambodia, which all suffer from drought, need to band together and go to China to negotiate some new rules.”

To be sure, none of this will be easy. As evidenced by the various stakeholders and levels of governance in Vietnam, it is hard enough to coordinate policy across the 12 delta provinces, let alone multiple nations with at-times difficult relationships.

But dams aside, there are steps like the ones discussed above that the people of Vietnam can take to return the delta to some form of its past self while buttressing it from the looming danger of climate change and rising sea levels. Now is the time to see whether those steps will be taken.

A boat repair yard outside Sa Dec. Photo by Michael Tatarski.

“It’s urgent, and on the other hand it remains a choice,” Minderhoud says. “It can be a strategy...to knowingly exploit resources...and it could be cost-benefit analysis that you actually agree it’s worth the cost of doing that. That’s fine, but it’s very important to realize that these changes are taking place and are predominantly driven today by human activities. So it’s our choice to continue or not, but at least you know what is going to happen in the future. It’s important to know what will happen instead of it arriving all of a sudden as a big disaster that you didn’t anticipate.”