[Special report] The environmental fallout of the Four Major Rivers Project

Posted on : 2013-08-03 14:08 KST Modified on : 2019-10-19 20:29 KST
Experts say it would now be best to remove the weirs and gradually return the rivers to their natural state
 North Gyeongsang Province
North Gyeongsang Province

By Kim Jeong-su, environment correspondent

The Four Major Rivers Project cannot be explained by the claimed objectives of securing water resources and preventing floods put forward by the administration of former president Lee Myung-bak. The sites of the project and the actual construction that was done have nothing to do with these stated objectives. This is why environmental organizations have alleged that the project is really a camouflaged effort to build a canal.

These claims are supported by the results of the Board of Audit and Inspection in Korea (BAI)’s audit of the Four Major Rivers Project, which was released on July 10.

In the BAI’s report, it can be seen that the Blue House was far more interested in the depth of the water rather than the amount of water storage or the ability to control water flow, which are the criteria for securing water resources and preventing floods.

In line with these obejectives, four small natural weirs morphed into 16 massive concrete weirs capable of keeping water at a depth of 4-6m (at the Nakdong River).

“We have no choice but to restore the four rivers to their natural state,” said Hwang In-cheol, head of the Nationwide Response Committee for the Four Major Rivers Restoration, which is made up of environmental civic groups. “However, the truth is that we have been so focused on the discussion of assessment and responsibility that we have failed to talk about the details of that.”

“But now that even the BAI is acknowledging the true nature and failure of the Four Major Rivers Project, we have to start talking about returning the rivers to their natural condition. We must do this to prevent the environmental disaster from getting worse,” Hwang said.

Lee Sang-don, a professor emeritus at Chung-Ang University, voiced a similar opinion. Lee, who is regarded as a reasonable conservative, was formerly a member of the emergency measures committee for the Saenuri Party (NFP).

Lee brought up the possibility of dismantling the weirs as a means of allowing nature to take its course on the rivers. “Water has collected behind the weirs, but there doesn’t seem to be anyone who is going to use it,” Lee said.

“The weirs don’t serve a purpose, and they are so pointless that there isn’t even a good reason to look into their financial soundness. All that the weirs are doing is putting stress on the water quality and the ecosystem,” said Lee. “Our only option is to get rid of them.”

1.5 trillion won (US$1.34 billion) was invested in the construction of the 16 weirs. The reason that discussion has already begun about eliminating them less than two years after construction is not only that they are unnecessary, but also very expensive to maintain.

The algae blooms that threaten the mid and upper reaches of the Nakdong River when the water temperature rises are regarded as the biggest cost that must be paid both by people and by the natural environment in order to maintain the weirs.

Even officials at the Ministry of Environment who claimed that more area for the water would dilute the blooms stopped denying the negative effect of the weirs after the BAI asserted in January that, “the amount of time the water stays behind the weir makes it more likely that algae will proliferate.”

Nor can the unease of Korean citizens about the appearance of the algae bloom and the threat to the environment be compensated with funds for buying and operating crafts to eliminate the algae and enhancing the water purification facilities.

Known factors influencing the appearance of algae blooms in rivers are nutritive substances, the time that water remains in one place, and sunlight and water temperature. These last two factors are beyond human control. The density of the nutritive substance phosphorus in the four rivers has long resulted in eutrophication.

The reason that there were not large algae blooms in the past is because the water was not stagnant for a long period of time. As a result of the installation of the weirs, the speed of the four rivers decreased considerably. The Nakdong River’s flow has decreased to one-tenth of its former speed.

The situation now is that algae blooms multiply out of control whenever the weather conditions are right.

The Ministry of Environment has focused on reducing the level of nutritive substances in the four rivers system by speeding up the timeframe for building sewage treatment plants. The result is that it succeeded in lowering the total phosphorus density in the area around the 16 weirs on the four rivers from an average 0.207mg/L in the first half of 2005-2009 to an average of 0.114 in the first half of 2012.

But this didn’t stop people living around the Nakdong River from coining the term “algae bloom latte” in the summer of 2012. (The Korean expression for “algae bloom” is very similar to “green tea”.)

“In order to control phosphorus levels and prevent the occurrence of algae blooms in the four rivers, we have to lower the total phosphorus density to 0.05,” said Kim Jwa-gwan, a professor of environmental engineering at the Catholic University of Pusan. “Technically speaking, the four rivers have effectively been turned into lakes, so we need to bring this level down to the eutrophication standard for lakes, which 0.02, which is effectively impossible.”

But even if it were possible, the problem is the cost. The water quality improvement project on the four rivers, which managed to lower the total phosphorus level 45% from 0.207 to 0.114, already cost 3 trillion won (US$2.67 billion).

Given an increase in the number of pollutants that must be disposed of on land because of a ban on offshore dumping, halving this figure once again would surely be enormously expensive.

The other problem is that even though all of this money is being paid to keep the river water backed up, there is nowhere to use the water.

In the South Korean government’s comprehensive long-term plan for water resources that was published in 2006 before the Four Major Rivers Project was unveiled, it was predicted that the shortfall in water around the Nakdong River would not exceed 136 million tons in 2016 and 156 million tons in 2020, even presuming the worst possible droughts in a scenario where the demand for water continued to increase.

This degree of shortfall could easily have been covered simply by building the small and medium-size dams included in the Four Major Rivers Project and increasing the number of dikes around the reservoirs.

There was no reason to build large-scale weirs that could hold 670 million tons of water.

Another way to resolve the issue of algae blooms would be to leave the weirs as they are and adjust the amount of water released from the sluices. This would be a partial return to the natural condition.

In this case, it would be necessary to look into the maintenance and upkeep costs for the weirs as well, and to consider their safety and what effect they may have on the environment.

The government allocated about 200 billion won (US$179.11 million) of the 2013 budget for maintenance of the country’s rivers and streams, which includes the maintenance and upkeep cost for the Four Major Rivers Project. The Korea Research Institute for Human Settlements put forth a higher figure, calculating that the cost needed for proper upkeep of the Four Rivers Project would be 600 billion won. This is a cost that would not have to be paid if the weirs are removed.

 July 27. The area had already been dredged
July 27. The area had already been dredged

The weirs have had numerous harmful effects on the environment. These effects include damaging the scenery around the rivers, shutting down ecological corridors around the waterways, and disrupting ecosystems by changing the reproductive environment for riparian organisms.

From 2006 to 2008, the Korea Institute of Construction Technology conducted a study in which it actually tore down the Gongreung 2 Weir on the Gongreung Stream in Goyang, Gyeonggi Province, and the Gotan Weir on the Hantan River in Yeoncheon county, Gyeonggi Province, and observed how this affected efforts to restore ecological corridors on the streams and improve water quality. The report concluded that removing the weirs was very helpful not only in restoring the ecological function of the waterway but also in improving water quality.

“Maintaining the weirs while adjusting the amount of water released would be effective at preventing algae blooms,” said Park Chang-geun, professor of civil engineering at Kwandong University. “The problem, though, is that this is no solution to the fact that weirs increase the risk of floods and that pollutants are accumulating on the riverbed upstream from the weirs.

”We must ultimately work toward dismantling the weirs and restoring the rivers to their natural state,“ Park said.

It does not appear that the cost of dismantling the weirs will be a major obstacle. According to calculations by the Korean Society of Limnology, about 10 billion won (US$8.96 million) should be sufficient per weir.

Even if all 16 weirs were dismantled, it would cost less than one year of maintenance and upkeep for the Four Major Rivers Project.

But even the experts who believe that it will be necessary to get rid of the weirs are not arguing that they should all be demolished immediately.

With the riverbeds dug as deep as they are at present, if the weirs were removed it is inevitable that the river level would drop even lower than it was before the Four Rivers Project. It is not known what effect this could have around the waterways.

Something else that must be considered is safety concerns related to changes in the movement of floods. What is necessary is close review, meticulous preparation, and a social consensus on the issue.

"While the logical course of action is to tear down the weirs and restore the rivers to nature again, these measures should not be pushed throughout without giving consideration to the people affected as the Lee Myung-bak administration did," said Kim Jeong-uk, professor emeritus at the Graduate School of Environmental Studies at Seoul National University.

"It must be done in steps, after gaining the consent of the people," Kim said.


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