By now many people may think that all of this mutterings by social media practitioners about the 3 Gorges dam has been just about generating clicks and getting people upset for no reason.
After all, the dam is still standing – so what’s the fuss?
The perspective to consider this entire media firestorm about the 3 Gorges dam is to understand the implication of a breach of this dam. We are not talking about just about a flood here, we are talking about the risk potential of the most significant engineering disaster in human history.
Of course, this does not mean that we are hoping in any way for the dam to fail. On the contrary, all we are doing is highlighting the risk of a dam failure given that information coming out of China is rarely transparent.
Our last post on the 3 Gorges dam was actually on the 22nd August 2020, where we highlighted the earthquake risk posed by the dam. We had also made an incorrect call on Typhoon Maysak’s course, which we acknowledged over here. In the interim, we did not really update anything about 3 Gorges dam because the weather outlook for the Yangtze river basin was mild, and bearing a seismic event, everything should work ok.
However, according to numerous weather models, all of this is going to change dramatically over the next 10 days. Starting tomorrow, the entire Yangtze river basin is going to experience torrential weather for the next week, which is shown below.
We are not talking about just about a flood here, we are talking about the risk potential of the most significant engineering disaster in human history.
To give you an idea of the scale of rainfall, the above chart shows that the entire upper basin on the Yangtze river is going to experience rainfall accumulation in excess of 100mm over the next 10 days, with some areas experiencing close to 200 mm. All of this water is going to come pouring down into the 3 Gorges dam about 4 days later, as it takes about 96 hours for the flood waters to travel from Chongqing to Yichang where the dam is located.
There are several other issues to point out.
Currently, the water level at the 3 Gorges Dam is at 157m , with the outflow at 28,400 m3/s. Since there is an expectation that the entire region would experience massive flooding, it makes sense for the dam operator to discharge as much water out as possible to make room for the incoming flood water. However, they are discharging only at a fraction of its maximum capacity of 100,000 m3/s, and much lower than the previous No 5 Flood Peak discharge rate of about 50,000 m3/s.
This is the picture of the dam as of now. The main spillway has not been used for the past several days. It does not make sense not to discharge water right now given the weather outlook unless there is a reason why the spillways cannot be used. Potential reason is that the sluice gates have sustained damage due cavitation, but that is a speculation as of now.
If that is indeed the case, then the No 6 Flood Peak which will start to form at the end of this week will be a very detrimental to the dam. We hope that whatever engineering issues , if they exist, can be rectified.