Lake Lanier Water Level Projection
AWS reader Lawrence Freil (known as “lf61” in our forums) has just built a slick JavaScript-based tool that helps estimate the future water levels of Lake Lanier.
Here’s how it works, in his words:
In previous discussions there have been mentions of the change in the rate at which Lake Lanier will drop due to the shape of the lake itself. As the water level gets lower the rate should increase. I set out to estimate this change in rate and from that project the number of days till empty.
I decided to make this a dynamic tool that could be used to see “what if” situations with varying water loss and the result is a dynamic html/javascript www page that allows you to enter the current water level, a daily water level fall rate and using the data derived from the fill charts will project the number of days remaining.
The tool itself contains a more detailed explanation of how the change in rate data was derived and if you see any issues with it, just let me know.
Lake Lanier Water Level Projection tool
November 30th, 2007 at 9:45 pm
What many of the projections neglect is the effect of the drought. All the projections seem to assume that the Lake Lanier water sources will continue to feed the lake at a constant rate.
In fact, it is likely that the water sources that feed Lake Lanier will continue to dwindle and that the draining of the Lake will decrease the water level even faster as it’s supply diminishes.
November 30th, 2007 at 11:20 pm
I really, really like this. Could you add one thing?
A horizontal line that runs from 1035 to the green curve, and then a vertical line where that intersection is, so we can easily see the days to deadpool using your tool?
I’d be happy to add your tool as another daily predictor I grab for the wiki.
December 1st, 2007 at 8:25 am
Predicting inflows is for the most part the same as predicting the rain. For any level of accuracy you get about 7 days ahead and even the the quantitative (how much) vs qualitative forecast (what area) are much further off. We do have historical inflow data for previous years and even in previous drought years the inflows tend to bottom in the Sept/Oct. months and peak around January. This trend is likely to continue even in drought conditions (only difference being the volumes). It should be possible to take the historical inflow data and create daily or weekly modification table to estimate the change in lake elevation should the historical tends occur. I’ll think about how to apply such a change.
December 1st, 2007 at 11:08 am
Charts are interesting, but ACE is playing games on amount of water remaining behind the dam at Lake Lanier. Once dead pool level is reached, then as water is withdrawn by pumps, then water inflow into the lake might end at dead pool and no longer flow out at all down the river.
December 1st, 2007 at 7:00 pm
Nice programming but way too simplistic to be a useful tool. It is missing too many factors related to water loss. It at least needs to take into account evaporation through including daily temps and relative humidity as well as usage of vegetation. The plants and trees (biomass) around the lake use water all year to seasonally varying degrees. Some of the large trees around the lake will each begin to use 500 or more gallons a day as spring and summer return. There are both evaporation loss and biomass water use estimating methods available. And as the lake shrinks the factors above and the loss through ground absorption will gradually reduce.
If you want to learn more about the impact of loss due to evaporation, Google the Great Lakes dropping levels. The current declines are not due to drought but to higher than normal evaporation rates due to higher than normal temps.
The Israelies greatly advanced the calculation of both loss evaporation and biomass usage factors. Regarding evaporation, there was a time in the 70’s they even experimented with converting open reservoir stored water into a gel to reduce evaporation.
December 1st, 2007 at 7:09 pm
There has been a lot of talk about “dead pool” and water no longer flowing through the dam. It is true that when dead pool is reached water will no longer flow through the primary turbines, however the secondary turbine is all the way down at 1020. In addition they have flood control sluice gates all the way down to the bottom. This was how they allowed the downstream to flow during the entire filling period. So even when dead pool is reached, the only pumps needed will be for those counties (forsyth, gwinnett, hall) that pull directly from the lake, and forsyth and gwinnett have already lowered their intake pipes. Most of Atlanta’s water comes directly from the river so the ACE will have to continue outflows at a minimum to keep these intake pipes underwater (as they did during the filling of the lake)
December 1st, 2007 at 7:20 pm
I didn’t know the flood control sluce gates were at the bottom of the dam - do they have the same level of control on those gates as they have on the gates that control the primary turbines?
That’s really good news - no need to pump over the dam if that’s the case.
Come to think of it - does anyone have an actual design for the dam?
December 2nd, 2007 at 1:27 am
IF61 > do you have documents to prove that sluice gates exist at the bottom of Buford Dam? If this is true, then talk of dead pool would be redundant. As for continued release of water to supply Atlanta it might not be possible anyway. Whatever the watershed dumps into the lake would be all that is available, so try splitting up about 400 to 500 million gallons of water daily to Atlanta, suburbs, and power plants too. Epic drought condition means severely reduced water flow down Chattahoochee River this next summer.
December 2nd, 2007 at 8:57 am
You guys all might get a good read from the following Government Report on expected water shortages:
http://www.gao.gov/new.items/d03514.pdf
From the report:
Under normal water conditions, state water managers in 36 states
anticipate water shortages locally, regionally, or statewide within the
next 10 years, according to GAO’s survey. Under drought conditions, the
number grows to 46. Water managers expect these shortages because of
depleted ground-water, inadequate access to surface-water, and growing
populations, among other conditions, and despite ongoing actions to
address their current and future water needs, such as: planning to prepare
for and respond to droughts; assessing and monitoring water availability
and withdrawals; and implementing water management strategies, such
as joint management of surface and ground-water resources. In addition,
water managers are reducing or reallocating water use, and developing
or enhancing supplies by increasing water storage capacity, or less
conventionally, seeding clouds to increase winter precipitation and
developing saltwater desalination operations to produce freshwater.
If the anticipated water shortages actually occur, they could have severe
economic, environmental and social impacts. The nationwide economic
costs of water shortages are not known because the costs of shortages
are difficult to measure. However, Commerce’s National Oceanic and
Atmospheric Administration has identified eight water shortages from
drought or heat waves, each resulting in $1 billion or more in monetary
losses over the past 20 years. For example, the largest shortage resulted
in an estimated $40 billion in damages to the economies of the Central and
Eastern United States in the summer of 1988.
AND
Current trends—such as declining ground-water levels and increasing
population—indicate that the freshwater supply is reaching its limits in
some locations while freshwater demand is increasing. Specifically, the
building of new, large reservoir projects has tapered off, limiting the
amount of surface-water storage, and the storage that exists is threatened
by age and sedimentation. Significant ground-water depletion has already
occurred in many areas of the country; in some cases the depletion has
permanently reduced an aquifer’s storage capacity or allowed saltwater to
intrude into freshwater sources. Tremendous population growth, driving
increases in the use of the public water supply, is anticipated in the
Western and Southern states, areas that are already taxing existing
supplies. Demand to leave water in streams for environmental, recreational and water quality purposes add to supply concerns. Finally, some experts expect that climate change will affect water supply conditions in all regions of the country, either through increased demands associated with higher temperatures or changes in supply because of new precipitation or runoff patterns.
Sounds a lot like there is no way to “fix” this issue, considering literally no one will be willing to give up their water as it becomes limited in a growing number of States. It appears you can expect chem trails over your heads, laced with who knows what, in hopes to avert water to Lanier. Never quite believed in all that until I read about the “cloud seeding” as the more “unconventional” method to replenishing water supplies in the above report.
BTW, where are the resource managers, scientists, city water management officials, etc. (anyone other than the backward ass Governor)? How much time are they dedicating to this problem and what kind of meetings are they holding? I haven’t seen much news indicating there is any type of short-term resource planning; not so much as an Advisory Board that has been formed to solve your issues. WTF? Rather than organizing prayer vigils, why does it not appear that a decision panel is being formed? Call in advisors from the West, where they have been experiencing shortages for years, call in a few American Indians, call in other nations, call in the Weather Channel people, call in ANYONE that can offer AN ACTUAL PLAN. I’m sure the airport would be willing to find a way to fly them in. I’m sure a few beautiful Buckhead hotels would love to put them up. I’m sure a few restaurants would be willing to cater their brainstorming sessions. I’m sure these guests could be treated quite well in exchange for a viable solution.
Just saw on the Weather Channel that Alabama’s Lake Howard is 9 feet below level and they are telling car washes they must remain closed on Monday’s. More economic impact…
As always, good luck over there.
December 2nd, 2007 at 9:02 am
Sorry about the carriage returns above. Copying for the government report didn’t work out as well as anticipated
December 2nd, 2007 at 9:56 am
I’m afraid I don’t have the blueprints, however there is a book called “The History of Lake Sidney Lanier” (http://www.lakelanierhistory.com). The term dead pool refers to power production, not outflows. Now one question I havn’t found an answer to is if the bottom sluice has been used since they got water up to the main power sluice levels. Hopefully they do regular maintance reviews because 50 years is a long time for not testing something and then expect it to work. I remember reading about NY’s water problems years back and they had not tested the main pipe shutoff from Niagra for so many years they were afraid to even test them for fear they would break in the closed position. Anyway, the gate was built into the dam to allow constant outflow during the filling and has always been there. They certainly didn’t shut off the river for over three years during filling. I would love to get actual blueprints/drawings but I suspect they are withheld for “security” reasons.
December 2nd, 2007 at 10:29 am
I did find a quick image showing the powerhouse and sluice gates before they filled the lake. As you will see all the gates are actually at the bottom of the lake (including those for the main turbines (however the turbines won’t spin if the lake goes lower than 1035 because of insufficient water pressure).
http://www.freil.com/dambeforefill.jpg
There are more images in the media presentation:
http://lanier.sam.usace.army.mil/multimedia/videos/LakeLanierConstruction-1.wmv
December 2nd, 2007 at 11:22 am
This is really important to consider, as it negates much of the “cut-off” predicting everyone’s been doing regarding the dead pool. I wonder why this hasn’t been seized upon by the ACE or state/city governments to assuage public concerns? Do they know something about the difficulties of opening the bottom gates that we aren’t thinking of? Does deadpool water have other major problems aside from increased bacterial content that make it inconsequential to the supply?
-st
December 2nd, 2007 at 11:33 am
lf61 — that image won’t load for me…
December 2nd, 2007 at 11:47 am
The only thing I have seen in print regarding the construction of the Buford Dam, that created Lake Lanier, refers that the power sluice channel was done first and water diverted down it as the rest of the dam was built. Also mentioned 3 pipe tunnels in the dam, but no mention of how they are used or operated. Once the lake falls to dead pool level, or below, then water would no longer flow out down the power channel. Extreme sedimentation and chemical contaminates are at the bottom of the lake’s dead pool pocket.
If a water tube was opened at bottom of the dam, then the worst sludge of the lake bottom would flow out first. That would mean right into the intake pipes for Atlanta located below the dam on Chattahoochee River. Seems the plan is to allow the watershed flow above Lanier to pour into the dead pool to keep it diluted, thus to be able to draw water from it directly.
US Army Corp of Engineers is being secretive about any continued flow of water down the river. Perhaps they have no plan at all and truly refuse to believe the drought is ultra severe.
December 2nd, 2007 at 12:47 pm
Sorry about the image, I had copied it to the wrong place. It is just a frame from the video presentation anyway. It’s very informative to look at how it was built. You can seen in the photos there are 4 total pipes. Two main turbines, one smaller turbine and one way off to the side (barely visible in most of the photos) that is a bit lower than the others. This is the sluice that just runs water through the dam. In one of the photos you can even see it flowing on the output side while the main tailpipes are dry.
There is a lot of misunderstanding and the ACE isn’t helping clear it up for some reason. The reason the ACE says there is roughly 300 days of water left is because nothing happens at 1035 other than we loose roughly 73,000 Kw of power (http://water.sam.usace.army.mil/buf-pert.htm). As the lake gets lower it will cost the water utilities to purify the water as it will have more bacteria (this tends to build up below the thermocline due to less mixing of the water). Otherwise 1035 is not special. I am concerned that as this is passed and nothing happens people will assume the entire water problem also a non-issue. I know the media loves to create a crisis to sell advertisements but when it is false it spreads disbelief.
December 2nd, 2007 at 12:49 pm
When dead pool level is reached, then the power channel gates of the dam would have to be left wide open for any flow to continue down the river. That is if the flow can still come out before Cumming sucks it out of dead pool first.
Imagine a scenario of perhaps just a couple hundred millions gallons of water still flowing down the Chattahoochee to Florida. After Lake Seminole runs dry, then Gov. Crist can scream till he drops dead. There will be NO water left for the mussels nor to operate the power plants.
December 2nd, 2007 at 12:55 pm
If61 > what if the tubes in the dam are clogged up or the release valves are jammed from neglect? ACE for some unknown reason does not mention those tubes to the press or the public. Are they defective?
December 2nd, 2007 at 1:07 pm
When I was at Lake Lanier a few weeks ago I drove down the gravel road to the below dam park. The old river bed that the dam sits atop seemed to still have a small flow coming out from under it. Perhaps one or all of the tubes operate but are not fully functional. Would be dangerous to try to fix the valves at this point. If they are damaged, then would have to be repaired when lake is completely empty.
December 2nd, 2007 at 1:57 pm
They aren’t valves per-say. They are huge metal plates that slide down in grooves in the outer wall of the dam structure (photos from the presentation show these pretty well). Not much to break here and I read somewhere they were upgraded from chains to hydraulic some years ago. My guess is that they test everything pretty regularly, but it would be nice if they would just come out and say so. On the minus side, I looked back in the historical data and at a glance I couldn’t see anything recent where the outflows of the dam exceeded the outflows of the turbines alone, and in fact in recent years they haven’t been running all 3 turbines most of the time (August of 2005 they did at least get them all up to maximum output!). Sediment is unlikely as all the pipes are pretty close to each other and the regular currents would pull it through rather than allowing it to sit. We need to find someone that works there for the inside scoop, but odds are there won’t be an actual outage till next August, and of course at that point it will be to late to attempt any real fix. It would be nice if the ACE would hold a press conference to explain to the media what things are really like, but my guess is nobody there actually has that authority. In the past I have toured a a couple of dam’s and they are for the most part surprisingly well run. They were offering tours back in March. It’s a shame we are to late to just go take a look.
December 3rd, 2007 at 9:52 am
So, just to be clear,
It looks like all the gates are at or near the bottom; the main turbines won’t have enough water pressure to run after 1035 feet, but water should still be able to flow.
That jives with the images of the water coming from the other side of the dam - it’s coming up from the bottom, and not sluicing over the top.
Well… that’s good then. Maybe I should start doing an ‘empty Lanier’ prediction instead of a deadpool prediction.
December 3rd, 2007 at 10:05 am
This is interesting.
Based purely on VOLUME LOSS - which doesn’t give two shakes about the surface area of the lake nor about it’s shape, there are 366 days of water left in the full volume of the lake, assuming the average volume loss holds true.
December 3rd, 2007 at 10:09 am
I agree with empty instead of deadpool as it doesn’t really mean anything with relation to the water (just power).
Also, I made some significant changes to the projection tool. I incorporated a seasonal adjustment factor to account for normal increased rainfall through the winter and less rainfall through the summer. It also should account for some seasonal evaporation since the basis for this adjustment would incorporate average evaporation by using historical differences in rise from peak to trough for lake level adjustment.
I also added a disclaimer just in case somebody assumed i knew what I was doing.
December 3rd, 2007 at 10:15 am
Nice. Thank you for both the deadpool lines and the updates on the predictor. One more request - could you extend past 420 days? Given the current fall rate and current depth, the predictor for the end of water exceeds 420 days.
I’m going to start tracking your tool as well in the predictor page.
December 3rd, 2007 at 10:25 am
Days max increased to roughly 2 years. This was to limit what javascript would do in the case of a zero or increasing (negative) fall rate.
Now if I have time, I would like to go back to around May of last year and see how the model jives with what actually happened.
December 3rd, 2007 at 10:28 am
Ugh - when you expanded the X-axis to two years, it severely reduced the number of data points it shows - put in 1051.68 and .1132 for elevation and loss, respectively.
Any way to get it to show 30 day increments?
I added both a deadpool and total volume predictor based on your model, by the way, and gave you credit on the deadpool predictions page for them.
December 3rd, 2007 at 10:43 am
I was trying to make it look acceptable in a variety of browsers. 30 does seem to work okay up to about 460 but then the numbers start to overlap and become unreadable. I tightened the range to keep it at 30 up to 460 then go to every 60 days.
December 3rd, 2007 at 10:48 am
I don’t suppose there’s a way to have it seperately tell us what the actual landing point for the deadpool and the 0-volume are? It wouldn’t even have to be on the chart, it could be under the chart or above it.
December 3rd, 2007 at 11:49 am
The labels for those positions are now above the chart, as well as the newly calculated lake drop below the days so you get some idea of the rate of change.
December 3rd, 2007 at 1:41 pm
ACE still claims a dead pool pocket exists in Lake Lanier, so perhaps the lake bottom behind the dam was dredged deeper during construction? If there is a bowl depression in the lake bottom, then even sluice tubes at bottom of dam would not access it completely. Nobody has posted a maximum flow rate from the dam tubes to the river.
ACE prefers the water to flow out the power channel to produce some electricity in the process. Perhaps the reason ACE wants whatever water flowing into the lake to still spill out the power channel. Water just going out the tubes bypasses turbines.
December 3rd, 2007 at 1:54 pm
Seems that ACE spokesmen should hold a press conference to explain the full operation of the Buford Dam. What exactly do they infer by using dead pool terminology? Are the bottom tubes just for emergency release of water during floods? What is the maximum flow of water out of the tubes? Does the lake have a bowl pocket that cannot be accessed to flow out? What is the actual amount of water in the lake versus all the cities, factories and power plant needs? Thus exactly how many days of water left in Lake? 6 months? 1 year?
December 3rd, 2007 at 2:11 pm
It it very possible that the lake has been dredged behind the dam and the river channel is actually lower than the dam by a small margin. The fill data considers the bottom of the lake 960 feet, but bottom of the flood control sluice, streambed and dam according to the ACE www site is 914. My guess is that the water between these levels is so little (given how narrow the lake would be) that it filled (and would empty) in a day or two. My chart considers 960 the bottom since that’s where the lake levels officially “started”. The chart at:
http://water.sam.usace.army.mil/bufacap.jpg
gives a good idea how little water would be left from 960 to 914. Also by the time the water gets that low it’s hard to call it stagnant. The inflow stream would cause turbulance with that depth of water so it would circulate much like the river down from the dam does.
December 3rd, 2007 at 2:16 pm
And the most important question: Exactly how much water is released daily from Lanier? AJC newspaper has claimed 2+ billion on some days. On November 15, 2007 the day flow was 2.6 billion, which supposedly was the highest one day flow since May 2007. But also an AJC article mentioned an extra 22 billion gallons released during June 2007 by accident. ACE cannot be allowed to fudge or lie about the daily amount of release. Otherwise how do we know if outflow is cut by 5% or 10% or 15%?
December 3rd, 2007 at 2:22 pm
Jay - the daily releases are a matter of public record and available at
http://water.sam.usace.army.mil/gage/acfhist.htm
Or much nicer through
http://www.tinymicros.com/cgi-bin/nph-lake.pl
December 3rd, 2007 at 2:22 pm
and lf61 - Nice! Many thanks on the changes!
December 3rd, 2007 at 2:30 pm
rkolter > can you explain AJC newspaper countdown clock for Lanier? A while back it said 98 days and falling, then recently 168 days and falling? What basis are they using and why all the changes? Seems like the paper is playing some kind of game or they want to keep us all confused.
December 3rd, 2007 at 3:44 pm
No Jay.
Not being rude, I just -can’t- figure it out. I really thought it was volume based until it jumped 30 days when my own calculation did not. Prior to that I thought it might be depth based and they were just using a smaller set of numbers (so that a very low flow day would screw with their average). But that wasn’t it either.
I get a value from it each day because it’s a public countdown, but I couldn’t even begin to tell you what numbers they use, if they’re keeping them accurate, or what. Right now their number is within range of the other predictions, suggesting that whatever formula they use, it’s not wildly off base.
I do know they are considering the deadpool, and not the whole of the lake.
December 3rd, 2007 at 4:05 pm
They are probably looking at your web page and averaging all the values you list :-).
You have put together a nice page. It is interesting that prior to adding the seasonal variation mine followed the other volume prediction values very closely but when taking into account the average rainfalls for Dec through Feb adds a good bit more time.
It will be curious to see how the values track what really happens. As you get more observation time with the various values you could add an accuracy indicator (how the previous predictions are tracking reality).
December 4th, 2007 at 11:22 am
Now they can’t be - they just jumped 20 more days.
Actually yours for the deadpool fits right in there. The 0-volume prediction is way ahead of my 0-volume prediction; only time will tell about that one.
Well, the values PERFECTLY tract what really happens of course - at least mine will, since they’re based on averages that update daily, they will accurately chart the course. If they start releasing 100x the water, the predictions will adjust accordingly.
What you want is for me to freeze the predictions at a point (like I did when I held the ACE to their “79 day” prediction) and then chart from there. I could do that for the volume predictions, but the depth predictions will necessarily change as the surface area contracts.
I could extrapolate what the end of month values would be from the start of month values, and then show the difference - that’d be kind of fun.
December 4th, 2007 at 11:24 am
Like an idiot, I responded to lf61’s message without indicating what parts I was responding to. D’oh. It’s paragraph by paragraph - the first of mine to the first of his, the second of mine to the second of his, and the rest to the third of his.
December 4th, 2007 at 12:07 pm
rkolter said:
>What you want is for me to freeze the predictions at a point (like I did when I held the ACE to their “79 day” prediction) and then chart from there. I could do that for the volume predictions, but the depth predictions will necessarily change as the surface area contracts.
The basis for a good prediction is to take into account the changes that occur over time. If it doesn’t then you can’t really trust the results. A month by month or longer accuracy percentage would indicate to the readers which can be better depended (both volume and level based predictions). If the level predictions aren’t accurate, then it is a flaw in the prediction, not the fact that the lake shrunk.
December 4th, 2007 at 3:29 pm
It just occurred to me that some of these models may not provide you with a graph where you can see what they expect in 30 days. In that case there really isn’t much you can do. To make forecasts easier on mine I just added level to the days along the bottom. I could also add a form entry that gives you the ability to mark any depth point or day point just like deadpool if that would make things easier for you. Just let me know.
December 5th, 2007 at 2:09 pm
Actually, since I only track deadpool and end of volume right now, that feature would be neat, but not necessary for me.
I think that I could do what you suggest as far as the prediction test goes - I can easily get the average depth loss or volume loss on any given day, and then just extrapolate where the level should be based on that, thirty days out. Then compare to the actual values.
Maybe when I’m bored this weekend I’ll look into doing that.
December 24th, 2007 at 2:24 am
2007 is at or near a record low for rainfall. Lanier started the year at about 1063 and will end at 1050, a drop of 13 feet. So it seems that even if 2008 matched that record low rainfall, we still end the year above deadpool level.
Unless the drought extends into the summer of 2009, this is much ado about nothing.