Some clarifications on the post of when the Guri dam will reach the critical level

March 8, 2010

(Picture of a section of the Guri dam a few days ago)

(I still have no Internet at home, rather than answering the comments, here are some clarifications on yesterday’s post)

1- What is the critical level?

Strictky speaking is 240 meters, but it is likely to be higher. Flow may have to be restricted and you have to worry about other technical problems, so a better number may be 244-245 meters, which will occur around May 10th. if it does not rain.

2.-What is the correct question to ask?

I think it is the critical level, not when is that the water stops dropping. The reason is that if it starts raining and the daily drop rate falls from 15 centimeters to 7-8 centimeters, you push the day the level gets critical 50-100 days into the future. Historically, by the end of June, the water flow has always been above 4,000 m**3/s, thus if the rains slow down the rate thirty days, the probability is extremely high that a positive equilibrium (More flow in than out) will be reached.

3.- What about the conical shape of the dam?

The shape of the dam should be or is  in the linear fit to the historical data. How fast the water drops is a function of inflows, the shape of the dam, evaporation and height. I don’t pretend or intend to model of those, I simply note that so far the fit is extremely good. I will keep monitoring it.

4.-This is not a severe drought year due to El Niño

While this is not a great year, there have been worse. The current outflow and inflows into the dam are above the worst ones historically for the same date. El Niño is a complex phenomenon, this is not the strongest one either, nor the longest running as noted in this post in January. El Niño is simply a convenient political excuse.

5.- What about the turbines?

I have not had recent information about how many turbines are online or not. This is a separate issue. My understanding is that one can not be repaired. Another has been fixed. That leaves seven off line, last time I heard.

I was a little more optimsitic when I wrote the post that I am now. It looks like assuming “240 meters” was the wrong thing to do, it seems to be higher, thsu it is going to be quite close. However, it may not last long. My worry is that if Guri is shutdown, blackouts will affect the oil industry, supplies, communications. It could be really bad for a few days. On the positive side, there have been some rains down there, inflows have moved up to 700 m**3/sec.

This slide show of Guri about ten ago days tell you the whole story.


40 Responses to “Some clarifications on the post of when the Guri dam will reach the critical level”

  1. Rodger Farrell Says:

    Amigo Miguel:
    Now in 2016 the Guri water level is in the news again, and that has given rise to a message I sent to some friends. You know much more about all this than I do but I thought you might be interested in seeing the message. ….

    A few days ago we had said that the rate of decline of water level at
    Guri ought to increase as the level gets lower due to the conical
    shape of the lake basin, but that “for the moment I leave that
    exercise to others.”

    But who can resist these interesting challenges ??
    Who can sleep at night with this problem hanging over him ??
    How much will the rate of decline increase from its present rate of
    8.5 cm . day as the water level goes lower ??

    Here is a suggested answer to this problem for the restless souls:
    If Carlos, or anyone, finds an error, kindly let me know so that
    I do not incur in serious, irremediable trouble.


    At Guri’s normal water level of 272 meters asl (above sea level)
    the total lake area is 4,250 km 2. This area corresponds
    to an equivalent circle with radius of 36.8 km, or 36,800 m.
    That is, as far as the water is concerned, it is the same as
    would be in a perfect circle of 36,800 m radius.

    We need to estimate the slope of the sides of the lake basin.
    Looking at pictures, some places are slopier, some are flatter,
    but lets suppose the average lakeside slope is 20 degrees.
    If that is so, then for every meter the water level drops,
    the radius of the effective circle of water decreases by
    1 / (tan 20 deg) = 1 / (. 36) = 2.8 meters.
    And likewise, since the total water level decline today
    is (272 – 245) = 27 meters the total effective radius decrease
    from normal level to now is 2.8 x 27 meters = 75 meters.

    Now if the water radius has decreased 75 meters, the effective
    circle area decreases like this:

    level radius area
    272 36.800km 4 250 km2
    245 36,725km 4 235 km2
    Surface area reduction 15 km2
    % of surface area 0.3%

    The volume of the daily decline in level of 8.5 cm of water is directly
    related to the surface area at todays water level. So the volume
    of 8.5 centimeters of water at 245 m asl is 0.3% lower than the volume
    at 272 m asl.

    This volume difference is negligible. And since the volume of water
    difference is negligible, the change in rate of decline of the water
    level (assuming constant inflow and outflow) will also be negligible.

    Note that this is the calculation for the entire 27 meter fall in water level
    from normal level 272 to now. The extra change in rate of water level decline
    due to a further decline now of each additional meter would be on the order of
    4% of the 0.3% for 27 meters or, truly negligble, and far less significant than normal variations in water inflow and outflow.

    Going back to paragraph (2), if the average slope of the lakesides
    is higher than 20 degrees …. not unlikely …. then the reduction in water volume is even less.

    Sleep well….


  2. […] Some clarifications on the post of when the Guri dam will reach the critical level « The Devil… […]

  3. Not too sure how I found this blog but glad I did find it. Think I was looking for something else on yahoo. Don’t know I agree 100% with what you say, but have bookmaked and will come back to read to see if you add any more posts. Keep up the good work

  4. moctavio Says:

    Thanks Mike, very interesting stuff, I dont have the info you ask for, but maybe Moses does or knows where to find it. I will post some stuff tonight if I have times that suggests you amy be right or evaporation may be very important too.

  5. Mike Kramer Says:

    I did a bit more data mining on the reservoir and came up with a surface area when full of 4250 km2. The current offtake rate is around 4500 m3/s and supply is 500 m3/d. This net offtake of 4000 m3/s equates to a daily drop in level of just over 8 cm/day. As the actual level drop is almost twice this rate, the current “wet surface” level is about half of what it was, i.e. around 2250 km2.

    If the shape of the lake follows the martini-glass model (i.e. straight walls under an angle) your extrapolation is valid. If however it has curved walls like a soup bowl or localized plateaus/saddles above 240 m, as the pictures suggest, you can get sudden accelerations of level drops, which can not be predicted from recent history. I would therefore consider your extrapolations as the optimistic case.

    I am looking at the efficiency of power generation and to do this need the height of the turbines. Based on google earth this will be between 130 (height of the river downstream of the dam) and 240 m above sea level. If anybody has this info, please post it in a reply.


  6. An Interested Observer Says:

    Juancho, I think we’re seeing the situation the same way, but differing on how to define “desire” (i.e., does the word implying wanting only or effort). Nada mas.

    Though I don’t know if Hugo believes he can get electricity for nothing – but he certainly believes that’s how he can get votes. 😀

  7. Juancho Says:

    An interested observer said: “Juancho, I’m certain that they have the DESIRE. What they don’t have is the willingness to pay the price, in monetary and other terms (i.e., ceding some control). (I’ll grant your point on the wherewithal, which plays right into the “other” part of what I was saying.)”

    It would seem that way but oddly, it’s not, at least it’s not according to the folks I have talked to that are tied in with SIN, EDELCA, CADAFE, EDC ENELVEN-ENELCO, OPSIS, and so forth. They want and have the desire for the electricity but have no desire to do the actual work needed to get it – like fixing a freaking turbine. They all wnt something for nothing – and if you’re Hugo C. himself, you actually believe you can get somethig for nothing. For example, you put in a thousand year old Cubano, who doesn’t know jack shit about electricity, in charge of the national energy program, and the result is … the Guri dam turbines not working.


  8. maracucho importado Says:

    when i saw the short cuts and ineptitude at the new PDVSA i knew EDELCA was next and installed an automatic generator set at my house more than three years ago.
    three hours of not power will go to 8 to 12.

  9. An Interested Observer Says:

    Juancho, I’m certain that they have the DESIRE. What they don’t have is the willingness to pay the price, in monetary and other terms (i.e., ceding some control). (I’ll grant your point on the wherewithal, which plays right into the “other” part of what I was saying.)

    “why is a country that has its principal export commodity selling at high prices having to take on debt. That is just insane.”

    Dan, are you just waking up? This has been the M.O. for years, so you shouldn’t be surprised. Oil prices are up? Borrow more money! Empty the FIEM! Raid the BCV! It’s the same old story. Just one reason why the whole thing is unsustainable.

  10. Juancho Says:

    5.- What about the turbines?

    I have not had recent information about how many turbines are online or not. This is a separate issue. My understanding is that one can not be repaired. Another has been fixed.

    Is this really true? Do you have a source on when, and who, actually fixed a malfunctioning turbine at the Guri dam in the last year?

    Also, if seven turbins ar still off line, what efforts are currently underway to fix them?

    Call me cynical but I simply don’t believe that the Chavistas have the wherewitall or even the desire to fix anything.


  11. moctavio Says:

    Spending is extremely inefficient and the “funds” no longer have money. Believe it or not the devaluation did not give the Government as much as most people think, PDVSA was selling $ last year above Bs.5 per $ to swap market, now it is 70% at Bs. 4.3. Expect about 5-6 billion in issuance between Govt. and PDVSA this year, forget the gold stuff. They cancelled the hdro power plants because Giordani objected, no cost-efficiency just his beliefs.

  12. ow Says:

    The article is here:

    They say it will be an increase of about 68k barrels per day. At present prices that is a loss of $1,7 billion dollars over the course of a year. With that kind of money they could have actually built the hydro-electric power plants. Or at least get the Chinese to help them set up wind turbines

    My issue with the gold wasn’t the risk premium – my issue with it is why is a country that has its principal export commodity selling at high prices having to take on debt. That is just insane. Being in debt is never profitable and Venezuela really doesn’t have any reason to take on debt.

  13. moctavio Says:

    BTW, he has been peddling that since last summer (the gold idea) I don’t think it will ever happen.

  14. moctavio Says:

    Merentes has been in love with that idea for quite a while. What he fails to understand is that if the gold is in Venezuela, it is the same as issuing a PDVSA bond, the oil is here too. Unless the gold is moved to Fort Knowx, having gold as backing will not reduce the perceived risk, anymore than the PDVSA bonds do (ytm at 13-14% today)

    As for the thermo generating power, the Government said to Reuters today that local oil use will go up 31% this year, this means some 200,000 barrels of oil that will not contribute to exports…

    The Chinese fund is in excahnge for oil, less cash flow.

    What can I say, this looks bad, very bad. I went to a seminar last Friday, everyone was so gloomy, I tried to play Devil’s (no pun intended) advocate saying that we can’t possibly have three down GDP years (2010, 2011, 2012) in a row. The unanimous consensus was, we will.

  15. ow Says:

    Off topic – in Ultimas Noticias it was reported that the BCV will start selling bonds backed by gold. WTF? Why do they need to do that? Debt is starting to pile up fast. Two weeks ago it was reported that the China Venezuela development fund (which is just a loan to Venezuela paid off with future oil shipments) was down to $1.5 billion (what exactly did they spend $6.5 billion on???) and they are trying to get another $12 billion from China.
    When your oil is averaging $60 to $70 per barrel and you can’t make ends meet something is wrong.

    BTW, all this build up of thermo generating power is going to eat into Venezuela’s oil exports and further hurt government revenues.

  16. Roger Says:

    Venezuela’s electric grid is maxed out! Not only Guri and other production plants but also the Transmission and Distibution system most of which dates from the last dictator are maxed out! Right now were just talking about getting past a major crash that could last days or worse. Finding Energy to drive non oil GDP growth is a dream until Billions are spent in that sector. We are talking years to solve this problem. Meanwhile most of LatAm moves forward.

  17. Bill, when the water level needs to be shut off, its way above that point. Look at the picture in the previous post, less than ten twelve meters to go, but this is far from the bottom of the dam.

    We can get electricity from Colombia (not much) litttle from Brazil. This year I think we will be ok, but next? I am not so sure.

  18. Bill Simpson of Slidell USA Says:

    I’m no scientist, but unless the lake behind the dam had right angle sides, and uniform depth, wouldn’t lowering the water level cause the amount of water remaining in the lake to decrease at an increasing rate as more dry land emerges? That would worry me. Can Venezuela get enough electricity from surrounding countries if those dam generators go down? If not, you could be looking at a life threatening crisis. You can’t do much today without electricity in any developed country.

  19. Gringo Says:

    The stats say this is the worst drought in 100 years

    Adolfo didn’t bother to read the comments in the previous thread. Or he did and deliberately lied.

  20. That’s a totally different point from the original one, with gold exploitation, deforestation, et., the numbers could indeed get worse.

  21. elnuevopais Says:

    I raise my point. With chavez history is just toilet paper.
    For example: PDVSA , sidor, cemex, agricultural production. If you look at the past to make a projection for the future, you are wasting your time.
    For this reason ,I think that this will end the same as the things above.
    That is why I am recommending all the family that I have left in Venezuela to start packing before it is too late.

  22. Moses Says:

    Miguel: as in said in a previous post, back in 2003 Edelca used a trick they are not using today: generate electricity @ 59 hz in order to slow slightly the turbines and slow down a bit the water flow. As a consequence Ac motors slow down and also clocks…

  23. moctavio Says:

    Those are historical numbers, not current ones

  24. elnuevopais Says:

    I don’t buy that…they are cranking up all the energy that they can get all year around. We can talk all we want, but until they can get the thermoelectric energy going ( I guess never), The dam will close a few months each year.

  25. As was evident from the state of what little utility infrastructure there was in Saddam’s Iraq, dictators don’t really understand the concept of ‘preventative maintenance’. The policy is “keep it running or we kill you – kthxbai!”

    If there is a choice to be made between protecting the equipment and squeezing out a little more electricity for as long as they can the state will certainly go with the second option. Rain is the only hope now.

  26. moctavio Says:

    The average flow during the year is 4.8 cubic meters per sec and the average flow is roughly the same, so it balances out, you have above average years, below average years, unless you upset the sources it works.

  27. elnuevopais Says:

    I read all this post and I wonder why nobody does a simple math. The daily water consumption is close to 5000 Mts /s. During 3 or 4 months the river provides 6000 to 7000. The other 8 to 9 months it provides less than 4000.
    Sooner or later it wont be enough.

  28. concerned Says:

    “In an article in El Nacional, from a press conference of February 7 or 8, Luis Carlos Solórzano of COPEI, says that of the 20 turbines at Guri, only 8 are operational.”

    That is even worse than I had heard but is probably more accurate. Back to my point from the previous post. Yes, this was a hard year for rain, but the REAL problem lies within the dam and not above it. If Guri were full, the rationing would continue.

  29. moctavio Says:

    The actual digging began in the early 60’s I believe. It was done in stages, first a smaller size dam and then bigger, the final size in 83-86 I think.

    Yes, pavones should be biting now like crazy, I did pick that picture to contrast the one from the previous post that shows the whole dam where the water surface is nt broken.

  30. StJacques Says:


    Apparently 1986, from:

    “1986 – La conclusión de Guri, hoy Central Hidroeléctrica “Raúl Leoni”; se produce en 1986, constituyéndose en un hecho histórico. Al finalizar la obra, la capacidad instalada de esa central es de 10.000 MW, la más grande del mundo en ese momento.”


  31. HalfEmpty Says:

    I think to be clear that the photo is a of a portion of the Guri resevior — and a higher elevation part too. Note the growth on what would normally be islands. Always interesting is the submerged trees, deadly to shear-pins, but a nice place to find fish.

    When was Guri Lake filled?

  32. StJacques Says:


    Miguel is correct. Victor Poleo says the records on the historical flows date back from 1950.

    The following quote I will post is from Victor Poleo at:

    “El agua del embalse de Guri es de conducta aleatoria, es decir: los aportes a la cuenca del Caroní fluctúan históricamente entre 6.500 metros cúbicos por segundo y 3.500 metros cúbicos por segundo, según registros desde 1950 a la fecha.”

    Poleo says elsewhere, in another article, that the records for both rainfall and water flows in the Upper and Lower Caroni were not kept until 1950, but I do not remember which article that was.

    Miguel, a second point and question for you on the turbines.

    In an article in El Nacional, from a press conference of February 7 or 8, Luis Carlos Solórzano of COPEI, says that of the 20 turbines at Guri, only 8 are operational.

    I’m just wondering how this information may fit in with what you have.


  33. AndyG Says:

    I found the earlier post about the water level changs to be quite informative. One factor that needs to be remembered in doing these projections is the shape of the basin of the reservoir. If it is not linear it may throw off the models, tho in general it should decrease in area as the water level goes down. When the lake is full with a big area with many sq KM covered, one meter of drop is a lot more water than one meter of drop when the surface area is 30% of that size. Think of a champange glass on a bigger scale this effect is really pronounced in limestone aquifers. I would also wonder if there are any groundwater inflows into the lake that might provide a constant base flow even after the surface rivers have gone down.

  34. Eric Lavoie Says:

    Sorry i meant the part about it being the worst drought in 100 years.

  35. Eric Lavoie Says:

    Adolfo lies this one:
    “The physical structure of the dam could be damaged by low water levels. The stats say this is the worst drought in 100 years, we are receiving all your rain as snow.”

    No it is not, stop spreading your lies, you were told how this was not true, so now please STFU.

  36. StJacques Says:


    First of all, my apologies for the multiple posts on the other thread. I’m not sure why they did not appear in a timely fashion, perhaps it was your DSL issue. But I wanted to offer you some encouragement that your post was being circulated.

    I have included an update within my earlier post at:

    which contains a link to this second entry you have now published.


  37. RWG Says:

    Chavez does not want rain. Without rain, more businesses will fail and an even bigger portion of Venezuela’s economy will be under Chavez control. Without rain, the internet, phone systems, television, radio, and email will not work, giving more Chavez control of information. Without rain, Chavez will control food and its distribution in Venezuela. Without rain, the streets and cities of Venezuela will become more filthy and full of trash, making Chavez more powerful as the only person with the power to clean them up.

    Quite simply, a shortage of electricity will give Chavez the power to ration electricity to those persons and businesses that support him.

    Of course, when all of Venezuela is being punished by shortages, it will not help Chavez.

  38. Adolfo Says:

    The physical structure of the dam could be damaged by low water levels. The stats say this is the worst drought in 100 years, we are receiving all your rain as snow.

  39. Gringo Says:

    If one ever doubted the old saw that ” a picture is worth a thousand words,” these Guri photos remove all doubt.This is not to disparge anything that Miguel or anyone else has written. What he has written and graphs he has posted are much appreciated. Just that the slide show gives one a gut appreciation of the problem. And to think that this is NOT the worst year.

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