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Why do I think there's more news coming up??

Why do I think there's more news coming up??

RE: Why do I think there's more news coming up??

And you reckon that this is somehow an 'Engineering Failure' or something, eh?

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
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The secret of life is not finding someone to live with
It's finding someone you can't live without

RE: Why do I think there's more news coming up??

(OP)
Yes I most certainly do. Anytime a river rises more than 15 meters above flood level , and that same river was dammed by the authorities less than a decade ago , I have to believe there was serious inability to comprehend local flood risk .

RE: Why do I think there's more news coming up??

or maybe a change in climate... which has nulified earlier data?

Dik

RE: Why do I think there's more news coming up??

" the country was entering a "critical period" with some 433 rivers affected by the floods - 33 of them reaching record water levels."

Seems like more than just one dam is involved.

RE: Why do I think there's more news coming up??

Sounds like the mother of all monsoons.

Good Luck,
Latexman
Pats' Pub's Proprietor

RE: Why do I think there's more news coming up??

I find this interesting since our West Coast weather has made a dramatic change over the last ten years or so. The weather is compellingly different. I wonder if all this isn't somehow related to the sudden suspension of airline flights? The uniform dispersion of exhaust from 315,000,000 gallons of fuel that was burned daily.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Why do I think there's more news coming up??

The suspension of flights over the US for several days after 9/11 caused a greater difference in daytime/nighttime temperatures due to fewer high-altitude contrails. NOVA had a program on that.

For China right now the big issue is the Three Gorges Dam. Even during the years of construction there was a great deal of issues surrounding corruption and workmanship. Chinese officials, to reassure everyone, boasted that it was built for a 10,000 year flood. In the time since then they state a 100 year flood. Now they have a 100 year flood in progress. This boast came from government officials so it is more of a political statement than an engineering assessment.

RE: Why do I think there's more news coming up??

The statement "water level behind the massive structure rose more than 15m above flood level" indicates the pond is 15m above flood level. Nothing is said about water levels downstream in article posted by OP, but the wide open floodgates with a +15m pond would unleash a torrent, and is reported elsewhere,

Fox reports that this is "The second highest rainfall in more than a half-century".

I could see a discussion about fit to task in the the context of flood control, which is both an engineering and a political question.


RE: Why do I think there's more news coming up??

Once dammed and the water regulated by the dam, development along the banks continues - eliminating natural flooding areas that previously protected downstream areas from floods and exposing more people to the risk. Wall breaches are more abrupt than overland flooding, hence less warning.
This happens EVERYWHERE.
The simple act of damming and developing reduces the timeframe of "100 year flood" by a major factor. In the case of the Yangtze, there have been floods with fatalities and destruction >bn$ in 1998, 2010 and 2016, too.

www.sparweb.ca

RE: Why do I think there's more news coming up??

"reduces the timeframe of "100 year flood""
Sorry, I don't get it.
Does the presence of dams actually increase the likelihood of flooding when infrequently heavy rainfall occurs?

Jay Maechtlen
http://www.laserpubs.com/techcomm

RE: Why do I think there's more news coming up??

I should let SparWeb speak for himself, but I think he is referring to the inevitable land use changes associated with dam building.  Increased stram flow rates, shorter times of concentration, simply covering a large amount of land with permanent water, etc.

RE: Why do I think there's more news coming up??

Jay, and Denial,
Yes that is roughly what I was asserting. When I say "everywhere" I mean it can happen anywhere that a watercourse is given some control by a major project such as damming. Then, land along the banks becomes more desirable for development (housing, industrial, commercial, whatever). That development inevitably changes shore slopes, runoff flows, and on the non-engineering side, the land value which influences political decisions.

Important to note that examples can be cited from any country you choose, and my country, Canada, is no exception. There's no desire to pick on China in what I say. It also happens in Brazil, USA, Germany, and so on. In 2013, much of the Highwood River flooding that ruined parts of the town of High-River Alberta (close to me) have been blamed on over-development of the flood plain and changes to the upstream slopes, which just channeled the slug of water toward the town faster and higher than it would have been with exactly the same amount of rain and runoff, if development wasn't there.

I'm not an environmental engineer so my understanding of the subject is weak. I just go by basic fluid dynamics and volume available to the river, which is what makes sense to me. A watershed with a slope of 100:1 being replaced by a 5 meter rockwall to carry a road will remove some cubic kilometers of volume that a flood could occupy. In my jurisdiction, all of this is hotly contested still, so the parts of the debate that pop up in mass media aren't always the most factual ones. It almost resembles the global-warming argument, as in "how could humans possibly cause an act of god such as a flood" while others have plenty of satellite and terrain maps showing exactly how, if only town officials would listen.

www.sparweb.ca

RE: Why do I think there's more news coming up??

(OP)
Seems a bit melodramaic, and if this is only going to drop the water level in one small area by 70 cm also seems a lot of hope and not much engineering went into the decision making process

https://www.theguardian.com/world/2020/jul/20/chin...

RE: Why do I think there's more news coming up??

Dropping 70cm on a flood plain doesn't sound like much, but can be very significant, when considering the length of the shoreline. If that happens on the length of a long river, aits many times the volume of the river itself.

Satelite maps? Problem is that everyone has an opinion, few of which are based on fact and, if it's based on facts, it's more likely to be facebook facts, or some other equally dubious source, and nobody wants to see any expert derived facts, because that might change their opinion, or actually prove them wrong. I wish every non-expert would take their opinions, write them down and put them where the sun don't shine. A perfect suppository for opinions.

“What I told you was true ... from a certain point of view.” - Obi-Wan Kenobi, "Return of the Jedi"

RE: Why do I think there's more news coming up??

There are no risk-free options; we always deal with tradeoffs. These are not moral decisions. All engineered systems can have adverse effects. And it is difficult to engineer around systemic gov't corruption.
In the US, dams have been substantially positive. In the Western US, without dams, it would be impossible to reliably provide drinking water to the urban areas, or irrigation to rural areas.
And if climate change is half as real as has been threatened - we need more reservoirs, not less. Like nuclear, more smaller systems would provide redundancy and reduce major failures. That is, when a failure does occur (inevitable), the impact is small. Say, compared to Oroville failing - in California, where new reservoirs are just about impossible to build, so we just make the big reservoirs bigger.
Yes, dams also come with negative consequences, and yes, with failures. As happens with electric cars and airplanes and windmills and wastewater plants.
And if you buy a house downstream of a dam, you shouldn't be contributing to this discussion.

RE: Why do I think there's more news coming up??

The discussion above focused on the flooding downstream of the dam providing flood control.
Here we also see flooding upstream. Any impediment land use plan needs to consider the land that could be flooded during wet weather flood control. Here the pond has risen to +15m (about 50 ft) given any reasonable shore slope that is an enormous land area.
Just a guess - this flood control storage area was not cleared of farms and towns due to the high population density and the demand for land.

This happened in Houston after Harvey, where land use plans did not require flood tolerant construction in the storage area of the Addicks and Barker reservoirs.
https://www.hcfcd.org/Hurricane-Harvey/Countywide-...

RE: Why do I think there's more news coming up??

Here's a live-feed of the Three Gorges Dam. For scale - there is a crane just above the letter "R" in the word "WATER" in the title on the feed. Not sure how long it will be up. https://www.twitch.tv/tgdfloodwatch

There is a report that a large chunk broke off in the last day or so, but it does not seem to have caused any further harm.

While dire predictions have been made in the past that were obviously wrong, failure of this dam would be the most 2020 thing so far.

edit - adding the link seemed appropriate.

RE: Why do I think there's more news coming up??

(OP)
looks like the 72 hour forecast is for heavy rain thru till Sunday afternoon , then moderating. China seems to be fixated with its arguments with the USA and might not be giving this area the attention it deserves. Supposedly 400 million live downstream of this dam

RE: Why do I think there's more news coming up??

Quote (3DDave)

failure of this dam would be the most 2020 thing so far

There's a turn of phrase I haven't heard before. Can't decide whether I'd like it still to be part of the language in twenty years' time.

A.

RE: Why do I think there's more news coming up??

(OP)
Based on the attachment supplied by 3DDave , it looks as tho inflow is now 150% of discharge volume , and unsurprisingly , water level at the dam continues to rise. Sur glad Im not responsible for advising what course of action to be taken on a daily basis,

RE: Why do I think there's more news coming up??

Quote (miningman (Mining))

Based on the attachment supplied by 3DDave , it looks as tho inflow is now 150% of discharge volume , and unsurprisingly , water level at the dam continues to rise. Sur glad Im not responsible for advising what course of action to be taken on a daily basis,

You can always do what the Army Corp did on the Missouri River - increase the outputs of the dams, even if it floods low areas downstream (like downtown Omaha, and the Ft. Calhoun Power Station). If you're trying to avoid the catastrophic failure, at least.

RE: Why do I think there's more news coming up??

This is China's Three Gorges Dam. Construction started on 1994, operation started on 2003. Below is a glance of its dimensions and power generation capacity.

Quote (wikipedia)

Made of concrete and steel, the dam is 2,335 m (7,661 ft) long and the top of the dam is 185 m (607 ft) above sea level. The project used 27.2 million m3 (35.6 million cu yd) of concrete (mainly for the dam wall), used 463,000 tonnes of steel (enough to build 63 Eiffel Towers), and moved about 102.6 million m3 (134.2 million cu yd) of earth.[37] The concrete dam wall is 181 m (594 ft) high above the rock basis.

The Three Gorges Dam is the world's largest capacity hydroelectric power station with 34 generators: 32 main generators, each with a capacity of 700 MW, and two plant power generators, each with capacity of 50 MW, making a total capacity of 22,500 MW.[11] Among those 32 main generators, 14 are installed in the north side of the dam, 12 in the south side, and the remaining six in the underground power plant in the mountain south of the dam. Annual electricity generation in 2015 was 87 TWh, which is 20 times more than the Hoover Dam.

There are multiple reasons for the construction of this dam albeit under the fierce protests from the environmental groups, and quite a few science communities.

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