A combination of drought and controversial
upstream water politics is setting up Southeast Asia for potential disaster.
BY STEFAN LOVGREN
PUBLISHED JULY 31, 2019
A SEVERE DROUGHT that has caused water
levels in Southeast Asia’s Mekong River to drop to their lowest in more than
100 years could have devastating consequences for fish, as well as the tens of
millions of people living and working along the river, experts warn.
The crisis began when critical monsoon
rains, which usually start in late May in the Mekong region, failed to arrive.
Dry conditions, driven by the El Niño weather phenomenon and exacerbated by
climate change, persisted well into July. At that time, observers say, the
situation was made worse by hydropower dam operators upstream, in China and
Laos, withholding water for their own purposes.
Although the rains finally began to fall
in the last week in much of the river basin, with water levels now slowly
rising, experts warn that the potential damage from the drought could be worse
than in 2016, when another drought caused forest fires around Tonle Sap Lake in
Cambodia and widespread disruptions to food production.
Many rice farmers in the region have been
unable to plant their main crop, raising fears of a heavily diminished harvest
this fall. Less water flow could also have a devastating impact on fish
reproduction in the Mekong River basin. This is normally the time when fish use
rising water levels as a cue to spawn and to disperse their young, but there is
little evidence of this happening so far this year.
Perhaps even more alarming, experts expect
that droughts and disruptions to the water flow of the Mekong will become more
common, and they warn that it could eventually lead to the collapse of the
entire ecosystem.
“With the completion of more mainstream
dams and the cumulative effects of climate change, that tipping point” for when
the Mekong can no longer sustain these changes “may be coming closer,” says
Brian Eyler, the Southeast Asia program director at the Stimson Center in
Washington, D.C.
Flood
Pulse
Originating in the Tibetan highlands, the
Mekong River flows through six Asian countries, including China, Myanmar,
Thailand, Laos, Cambodia, and Vietnam, before emptying into the South China
Sea. The river basin is home to the largest inland fishery in the world and
more than 60 million people depend on it for their livelihoods.
Few rivers in the world rise and fall with
the seasons as much as the Mekong, which can drop up to 40 feet in some places
at the end of the dry season. When the monsoon rains arrive, they normally
produce a flood pulse that brings with it sediment essential to agriculture as
well as enormous amounts of larvae and tiny fish, including many critically
endangered species such as the Mekong giant catfish, that are swept into the
Tonle Sap Lake and other floodplains where they can mature.
Every year, scientists have been
collecting samples of these tiny fish and larvae on the Mekong River near Phnom
Penh, Cambodia. However, so far this year, sub-normal water levels have
produced no flood pulse, and the researchers have not seen any dispersal of
fish larvae.
“Without the flood pulse, fish may delay
or skip spawning,” says Zeb Hogan, a National Geographic Explorer and fish
biologist at the University of Nevada, Reno, who leads a USAID project called
Wonders of the Mekong. “For rare and endangered species, this situation
threatens their survival, and for commercially important fish species, future
harvests could be significantly reduced.”
According to Peng Bun Ngor, a fish
ecologist with the Cambodian Fisheries Administration, the low river flow also
forces brood fishes to concentrate in spaces where they become more vulnerable
to being captured by fishers. “This adds to the existing problem of low
recruitment,” he says.
Dam
Politics
This year, the dry conditions in the
Mekong region persisted due to warm Pacific Ocean currents known as the El Niño
effect. But climate change is also a driving factor, experts say, causing the
monsoon season to shorten considerably.
“I have no doubt that this present drought
is caused by the shift in world weather patterns as the result of global
change, especially warming trends, and it would not be surprising if it lasted
several more years,” says Peter Moyle, a biology professor emeritus at the University
of California, Davis.
Moyle and others say dams on the upper
parts of the Mekong are contributing to the degradation of the entire river
system.
“Dams collect sediment, block fish
migrations, and create reservoirs that support a fraction of the fisheries that
the equivalent reach of flowing water would support,” he says, adding that the
dams will worsen the effects of drought.
China, which operates 11 dams along the
main stem of the Mekong (or Lancang, as it’s known in China), has come under
particular criticism for how it operates its dams in secrecy without much
regard for water flow downstream. It is not a member of the intergovernmental
Mekong River Commission, which was set up in 1995 to facilitate regional
dialogue in the lower Mekong River basin.
China’s decision to halve the water
released from its Jinghong Dam for two weeks in July, due to “grid
maintenance,” is believed to have contributed in large part to this year’s
historically low water levels in the Mekong River. Chinese promises to release
more dam water in the future have only served to raise worries over the extent
to which China controls the river flow in the Mekong.
“This highlights underlying inequities
among Mekong basin countries,” says Sarah Null, a professor at Utah State
University in the Department of Watershed Sciences. “Richer nations reap more
benefits of hydropower dams, including economic benefits and increased energy
supply, while poorer nations are more affected by environmental degradation and
reduced food security.”
'Battery
of Asia'
Many experts are particularly concerned
about the environmental impact of Laos’ plans to turn itself into “the battery
of Southeast Asia” by building dozens of hydroelectric dams on the Mekong and
its tributaries and selling power to neighboring countries.
Earlier this month, at the same time China
reduced the water output from the Jinghong Dam, Laos conducted trials on the
giant Xayaburi dam in the northern part of the country, its first hydropower
project on the main stem of the Mekong, scheduled to go online in October this
year. The trials may have further disrupted the Mekong River’s flow.
One of the poorest countries in the
region, Laos already has close to 50 hydroplants operating on various Mekong
tributaries and more than 50 planned or under construction, several of them
along the main stem of the Mekong. Last year a dam collapsed in southern Laos,
flooding large areas and killing dozens of people. Environmentalists have long
warned that the Lao projects carry environmental costs that are not fully
appreciated or factored in to the decision-making.
“There is a system of total anarchy for
hydropolitics and hydropower in the region,” says Eyler, who is the author of
the book Last Days of the Mighty Mekong. “There was no overall vision for what
the ‘battery of Asia’ would look like, and now there is no vision for how that
battery will operate.”
Still, there are signs that some countries
in the Mekong basin are moving toward alternative forms of energy. Officials in
Cambodia have expressed doubts about its plans for two, Chinese-constructed
dams on the Mekong River in the northern part of the country, as Cambodia aims
to instead increase its solar energy production.
Hogan says the Mekong must avoid the fate
of other heavily dammed rivers, like the Colorado in the U.S., which has seen a
complete alteration of its natural hydrography and the near total failure of
spawning and recruitment of most native fish.
He points out that while the Mekong basin
has proven remarkably resilient for many years, it is now facing unprecedented
pressures.
“The accelerating pace of change, coupled
with cumulative impacts of transboundary stressors, and the impending impacts
of climate change, point to a fear that the river, which is the lifeblood of
most of Southeast Asia, will gradually lose function until it no longer
supports the huge diversity of wildlife and millions of people that depend on
it,” he says.
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