[Viewpoint]It’s too early to evaluate the canal

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[Viewpoint]It’s too early to evaluate the canal

The controversy over whether to construct President-elect Lee Myung-bak’s cross-Korea canal project continues. While the focus of the dispute has already moved on to the validity of the project, the technical data used to justify the project should still just be considered merely ideas. Having been involved in business and research about water resources, I believe the following technical analyses are necessary before any ground is broken.
First, we need to thoroughly study the possibility that the construction of the dams, designed to secure enough water to operate the canal, will cause problems for the neighboring farmlands and streams and rivers.
The water level directly downstream from the dam, or right below the dam, is normally lower than the rest of the land.
The level of the water directly upstream of the dam, right before it reaches the dam, is generally higher.
If the water level is higher than the farmland right next to the dam, an irrigation problem could arise.
That’s because the higher water level increases the level of the water table in the neighboring farmland, causing water to well up in the fields. Crops cannot be grown in such fields.
A considerable part of the country’s agricultural land is located in the lower grounds around the site of the planned canal. When the level of the rivers or streams rises, it could cause substantial drainage problems.
In contrast to the water upstream of the dam, the normal water level of the water directly downstream of the dam could get lower. That, in turn, would lower the water table. If nearby rivers dry up, it would cause even more trouble to the ecosystem.
Since the water level of a river and the level of the water table are connected, the construction of the canal could change the whole water circulation system.
Considering the fact that our groundwater survey is not complete, we need to collect field data to analyze the potential changes to the water circulation system.
Second, it is essential to conduct geological research on all the relevant sites.
According to the proposed plan, the riverbeds will be dug down so there is enough water depth. The sediment removed in that process can be sold. That will pay for a considerable part of the construction of the canal.
The riverbeds consist of different materials, depending on where it is located.
For example, the section around Paldang Bridge has an exposed rock bed, while the section around Nakdong Bridge is largely sand.
According to the Construction Standard Estimate, the cost to blast the rock bed of a waterless riverbed is 6,500 won ($6.90) per cubic meter, 10 times the unit price of gathering sand, which costs 650 won per cubic meter.
In most rivers in Korea, the amount of sand and gravel has decreased after multi-purpose dams were constructed on the upstream side.
The sediment tends to move to other areas, making the upstream riverbeds thinner.
If the riverbed gets too thin and has to be blasted deeper, the construction cost could rise significantly. To accurately calculate that cost, a geological survey on the field is absolutely necessary.
Thirdly, a realistic dredging plan should be proposed. Due to global climate changes, Korea has experienced more severe and more frequent floods recently.
A river with a sand bottom, such as the Nakdong River, changes its course when flooded.
When a flood occurs after the grand canal is constructed, the water will not just flow through the main canal. It will go through all the sections of the rivers and streams, carrying sand.
After the flood, sand will flow from the upstream side to the downstream side and accumulate. Dredging is an essential process to keep the main canal deep enough for ships to navigate through.
The range and scope of the dredging are also closely related to the possible number of days that the canal operates each year. We also need field data to evaluate the dredging plan.
We can’t discuss the validity of the project without first conducting technical research, analyzing the drainage problems and conducting field geological surveys about the main canal dredging plan, which could all make a critical difference to the cost of the project.
We should accept the outcome of the field research and data analysis.
The opportunity to conduct the research should be given to Korean researchers and engineers who already have world-class technology and are ready to advance into the international market.

*The writer is the head of the Water Resources Development Projects at the Korea Institute of Construction Technology. Translation by the JoongAng Daily staff.

by Kim Sung

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