Recently I have been seeing a lot of Facebook and Twitter post about the potential failure of the Three Gorges Dam in China. Most of the posts are speculating about total failure of the dam. This Twitter thread is a case in point:
I think that looking at a total dam failure potentially misses the more likely partial failure and I thought that I would look at some failures that don’t involve the total collapse of the dam, but are still very bad. Here is a simulation of what could happen if the dam fails.
To call it potential disaster is understating the case. A small dam failure in Jonestown PA is still talked about a century later as a major disaster. If Three Gorges fails, the scope of the disaster will be incalculable.
First of all, here is the Wikipedia page for the Three Gorges Dam.
Here is a recent NASA post about the dam.
All hydro dams are pretty much alike.
The difference is size. Three Gorges is by far the largest hydro plant in the world. According to the Wikipedia Three Gorges delivers 22,000 megawatts or 2% of China’s electricity. If the Hydroplants fail, the consequences for China’s electrical grid will be enormous and there will be grid crash all over China. As the water rises, the head on the turbines also rises and there could be a hydroplant failure if the penstocks are not shut down. This happened in Russia in 2009 as seen on the videos here:
Another potential failure is spillway wear. As spillway is a how dam operator relieve pressure on a dam.
At the time I post this, there is a livestream of the Three Gorges dam and all the spillways are open.
The problem is that Spillways are not generally designed to withstand constant use and wear, as happened in California a few years ago.
There is also the issue that arises from wear as a result of hydraulic jump and erosion.
The most likely failure at this point is overflooding. Looking at the Three Gorges dam site, if the dam overfloods there could be spills on each side of the dam down low areas on each side of the dam. I don’t know what the ground there looks like, but there could be a great deal of erosion very quickly if it start. In fact that will probably be the cause of the dam’s failure, if it fails. It looks to me as if the engineers in charge of the dam are taking every step to prevent the catastrophe from happening, even if there is a conspiracy theory concerning Wuhan and the WHO and flushing the evidence. In spite of the videos and the rest, it looks to me as if the flooding is a necessary evil. Perhaps the dam should not have been built in the first place, but that was not my choice and sometimes you take risks.