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Comment by daveslash | Hacker News Reader

Glad I read the article. At first I (naively) thought "why? just pump more seawater?" But according to the article "it takes around 50 million gallons of fresh water to move a ship through a lock. The panamax locks lose more fresh water than the neo-panamax locks, which have a recovery system that can reclaim 60% of the water" -- A spot check on the maps shows Gatun Lake (freshwater) in the center of the isthmus. Wikipedia says it is fresh, but human made.

Is anyone aware of the reason for creating the interior of the canal as a freshwater passage, as opposed to just mixing ocean water willy-nilly? Such mixing of water would probably not pass current environmental concerns (with good reason), but curious what the reasoning was from a 1913 perspective?

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Zonian here. There was zero chance of ever creating a lock free canal. The amount of digging required for that was not possible in the early 1900s. I think pumping water in those days was far too impractical. Ships need to get raised 85 ft and then lowered 85 ft for the passage. Using gravity to fill the lock chambers was an ingenious solution and minimized the amount of digging. Thousands of people died building the canal and digging from Gamboa to Gatun just wasn’t going to work.

In the rainy season there aren’t any water issues. It’s the dry season that is the problem.

It’s three months into the rainy season and they expect to keep restrictions until September next year.

The problem is some years the rain isn’t enough to cover the demand.

I’m not up to date on things now. Thanks for the information.

Prior to the handover of the Canal there weren’t any issues with water during rainy season. But Panama City has ballooned in population and the ships going through the canal now are bigger on average. We Americans kept people out of the drainage system for Gatun Lake. We left the jungle alone. I don’t know if there has been a destruction of the jungle around Gatun Lake.

It seems like a perfect storm of more dry years, deforestation (although not much in the last decade), more water demand from the city, and more electric demand on the dams.

I hope my prior comment isn’t taken as derogatory toward Panama. Based on when I was last in Panama they’ve done a great job of governance. At least compared to when the Canal Zone was still an American territory. I think, overall, we Americans by 1970s ended up being detrimental to the growth and development of Panama. While it bothered me to lose my hometown I can see the Treaty was the right thing to do.

I didn’t take it that way. I think Panama owes its existence, the canal, and its democracy to the United States. Also the close ties have been a huge cultural and economic boon.

Panama has developed nicely since Noriega was deposed.

Panamanian here. The forest in the Canal watershed is pretty well conserved. The issue now is related to climate change and reduced rainfall. The new locks demand more water, though I can't say if not having those would make a difference in the current situation.

The Canal authority wants to dam more rivers and displace 10k people to make sure there is enough water to keep the thing running. Tens of thousands were forced out of their homes to build the Canal originally. It's fair to question how far Panama should go to keep being a canal country

I had read about rainfall problems some years ago. I thought it was more of one time occurrence sort of thing. Humans have done a remarkably good job of messing up the environment.

> how far Panama should go to keep being a canal country

Country resources that provide wealth need to invest into other areas that will supplement income. Is the canal taxing and putting that into other projects that are on a trend to displace the income from the canal?

As a Canadian I don't know Panama for anything but the canal. Are there things that place it in the top 5 of the world that would justify not being a canal country?

Just dig a tunnel woooooooo

Sorry, things got a bit musky there for a moment.

I wonder how many megaprojects get kicked off from a nose bender, especially in it's heyday. Perhaps the hubris of humanity is just the hangover of a boardroom bathroom break.

I mean for a lot of megaprojects or crazy ideas like "just dig a tunnel lmao" or "let's dig a canal to connect the oceans" it's not a matter of "is it possible" but "who's going to pay for it"; the rest is time and work, worst case it can be done with a shovel and a lot of patience.

This is why I don't understand this notion of ancient projects like the piramids, stonehenge or the moai being impossible; it just took a long time and a lot of people to do.

85 feet is actually way less than I expected, I thought they were going over a small mountain.

Are there any serious plans to dig it a bit deeper? Even taking 1 metre off the highest part seems like it would be significant.

Salinity issues aside, in my understanding locks generally don’t pump water at all: they work entirely on gravity. In effect this means that a burst of water flows downstream every time the lock is cycled.

Correct.

Exactly, they basically harness the natural water cycle (rain to watersheds to waterways to ocean).

The one exception is with these new locks, I bet they pump a bunch of the water back now instead of releasing it, that's how I expect they get the 60%.

Nope, it's not pumped. It's a clever system where there are several storage basins at different levels.[1]

In the 1960s and 1970s, there was a nuclear reactor mounted on a ship to provide power for the Panama Canal. This reduced water loss via the hydroelectric plant at Gatun Dam, leaving more water for the locks.[2]

[1] https://en.wikipedia.org/wiki/Panama_Canal_expansion_project...

[2] https://en.wikipedia.org/wiki/MH-1A

Truly incredible, thank you!

Perhaps the solution is as simple as invest in more electric generating capacity in Panama. At 8 degrees off the equator, solar is plentiful. One could use lake Gatun for pumped hydro storage as well.

Would there be enough elevation change to generate significant hydropower, though?

It currently generates hydropower, so I suppose so.

Another comment says ships are raised 85 feet during the transit, that sounds like enough to me if that is correct (not a hydropower engineer)

Apparently it’s 6 MW, which ain’t nothing, but isn’t a tremendous amount either. I don’t know what a typical battery storage facility can put out instantaneously - I would think more, perhaps substantially more. Though the lake certainly would have the capacity advantage!

Another commenter noted that they did this in the 60s and 70s, apparently there was a floating nuclear reactor there so they didn't need so much hydro power, keeping the reservoir more full

But they therefore depend on rain to work; thanks to climate change and changing weather patterns, that's no longer as predictable as it once was.

I mean when it comes to the Panama canal, pumping water upstream is an option, but as another commenter mentioned, it's a lot of water and will therefore cost a lot of energy to do.

Much of the route is pre-existing river and lake, the whole thing is an extension of a watershed.

FTA: “...the canal and the lakes and rivers that make up its watershed, which also provides fresh water to three cities, including the capital.”

Presumably, “people actually need to live in the area, and cannot drink salt water” was a factor.

It's because the Panama canal was constructed by connecting several previously naturally existing (fresh) waterways and a big lake, to the ocean on both side. The whole point of the locks is to raise and lower the ships to the higher elevation at which the lake sits. Water runs downhill, it starts as rain, then to rivers and lakes, then the ocean. So in this case rain and natural watershed basins drain into the lake and then the locks release it slowly down to progressively fill each lock, until the water is at the ocean, at which point it can't efficiently be separated from the seawater, so it just becomes part of the ocean.

The people there drink the fresh water and chose to settle in that area originally because ot was there. We then built a canal after. It wasn't like we built the Panama canal as a water source for the local folks.

> It wasn't like we built the Panama canal as a water source for the local folks.

Right, I am saying that the effect it would have on the existing water source is a probably a factor in why “allow more free mixing of saltwater / pump more seawater to deal with drought conditions impacts on the canal” is not done.

Not that the Canal was built as a water supply.

Gatun lake is man made. There was no lake as such prior to the building of the canal. There also weren’t a lot of people living in the area of what is now Gatun lake. Between Colon and Panama City was very sparsely populated.

About 40k people were displaced after building the Canal, not necessarily because they were in the way[0]. We like it there and I'd rather have fresh water than have the canal

0. https://www.amazon.com/Erased-Untold-Story-Panama-Canal/dp/0...

I’m surprised it’s that many people. I’d be interested to know if the displaced people primarily lived near the railroad. Colon was a small city back then so I did not think it could be so many people. We in the Zone weren’t taught much about the darker side of the building of the canal.

It seems like you could build a separate salt water basin that would hold the pumped sea water, so as to avoid having to pump it into Gatun lake. Then the salt water could be pumped into the locks to supplement the fresh water, when fresh water levels are running low. The pumps could be powered through solar or hydropower.

From the article: "This was to reduce salination of the freshwater in the canal and the lakes and rivers that make up its watershed, which also provides fresh water to three cities, including the capital."

Panama City is pretty thirsty.

This is how they made the lake: https://en.wikipedia.org/wiki/Gatun_Dam

I'm assuming flooding the other way around was more expensive than creating a fresh water reservoir by building a dam.

One of the reasons was to control the Chagres River. The creation of Gatun Lake created a freshwater reservoir higher than sea level. Vessels enter the Canal, climb up to the level of the Lake and are dropped back down to sea level. I have to wonder if the third set of locks (what I think they're calling Neo-Panamax locks) uses more water than the original 110 x 1000 locks. There must be a way to recycle water for use in Panama City and Colon. It's not practicable to re-use the water for canal operations because the water would have to be raised back up to the level of Gatun Lake and it would take an enormous amount of energy to do so. As I recall, spillage from canal operations was never used to generate electricity, but that might no longer be the case.

That was a surprise for me too.

How strange to look it up on Google Maps and see container ships on a lake

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