The Dangers of Low Head Dams (2019)
practical.engineering
practical.engineering
A video of me surfing this wave.
https://www.instagram.com/reel/CPgfVHPlNJx/?utm_medium=copy_...
Asking because I used to live near Bend, Oregon, which had a similar lowhead dam problem that they turned into a whitewater park with three separate channels of rapids. Love it when cities fund these sorts of things.
https://www.bendparksandrec.org/facility/bend-whitewater-par...
It's a privately built setup with a serious investment in the order of a million euro. A year pass costs us 440 euros. There are also day tickets available and there is a small bar for food and you can rent equipment.
Company is
I've already seen Instagram pictures in the past even though I have no account, but I see no way to do it now, is there a trick to do that?
https://krcproject.groups.et.byu.net/browse.php
are amazing: for many of these I don't think I would have considered them frightening at all from their appearance. Most of them look tiny, but these are all places where people were drowned by the current.
https://www.youtube.com/watch?v=NeCaEHsIa_U
https://geotripper.blogspot.com/2018/08/damned-if-you-do-dam...
This improved our downtown as it allowed us to also alter the river channel and opening up some land to build new parks on. Paddle boaters can travel much further, and the river ecology is improving drastically.
Maybe that's what causes incision? But hydrology isn't my area of expertise.
This is very different from an exhausted swimmer, or the evolutionary dead end default state of just chilling in the water because their amoeba brain flipped off
In general, don't spread anecdotal safety advice. Someone might die.
[0] https://www.americanwhitewater.org/content/Accident/detail/a...
This is terrible if not unresponsibly dangerous advice.
The top comment has a link to a database with cases of people drowning. The common pattern: if life vests were mentioned then those in the party who drowned were those who either took off their PFD or didn't wear one to start with.
Your best chance is to make it to the side of the river where the currents are less or nonexistent. A life vest increases your chances of making it there alive. Taking it off to dive down to some deep water outflow because somebody mentioned that stunt in some anecdote will get you killed for sure.
Not knocking him or the channel, I enjoy watching his videos and the recent collaboration with Lock Picking Lawyer was great.
Just wondering how it’s structured because it was so well produced from the first video.
It’s rare to see a maker create such polished videos from day 1. If he’s truly independent, he deserves even more credit for his talent.
While not mentioned in the videos, I'm guessing he also has the ability to ping some tough questions off people who would point him in the right direction quickly, but my guess is it's just a big passion and he's good at it.
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videogamedunky - video gamesGood article generally, but that's a super misleading statistic, or at least easily cherry picked to support a point. Dam failures in general are pretty rare, and fatal ones are even rarer.
Imagine if there was a bad but not Johnstown level fatal dam failure 25 years ago. You can tell two radically different stories if you choose to compare deaths over the last 20 years vs last 30.
The author's point would be more convincingly made if they talked about fatal dam failures over time and demonstrated that they had nothing up their sleeve before making that comparison.
Incidentally, you get naturally occurring keepers as well. I'm not privy to the full details but there was a drowning in the BWCA in 2002. AIUI somebody took a dip in a hydraulic below a falls along Horse Portage and wasn't able to escape. They went through too many times and could not be resuscitated. As I understand it, they were pulled out in an extremely risky and improvised rescue attempt, but it was too late for the victim.
It was near the take out, but if you messed up and didn't break for the bank, you were going over it.
Paddling buddies said that if you messed up, the best bet was to gain as much speed as possible and try and get over and then through it. If you got caught by it though, you were likely to drown, as it was a keeper.
The vertical eddy is called a "keeper" around here. The way to escape? Swim to the bottom of the river. Totally counterintuitive and hard in a panic situation.
His death led to some legislation here in Massachusetts about inspecting, marking, and, where feasible, removing these "roll dams."
It also led to race judges making sure racers do the portage and don't try to shoot the dam to save a few minutes.
That turned into a catastrophic problem last year in Michigan. Heavy rains breached the Edenville Dam, and then the Sanford Dam downstream, on the Tittabawassee River. They're still cleaning up even now.
https://en.wikipedia.org/wiki/Edenville_Dam
https://www.metrotimes.com/news-hits/archives/2021/05/17/vic...
Quite surprisingly, the incidence of deaths from whitewater kayaking and rafting is around 6 deaths per million participant days, compared to around 150 deaths per million participant days driving in cars[2].
Because the participants are removed from the population, it seems different from the case where they aren't.
I know those numbers b/c it lets me tell my parents that whitewater kayaking isn't as dangerous as they think.
And rafting / kayaking is definitely a calculated risk. Skill is involved. Freak accidents can occur that just wouldn’t if you weren’t on the river, but if one is smart about it, it can be about as safe as any other recreational activity (skiing, boating, mountain biking). With friends trained in rescue and experience the safety margin goes up.
For others reading this, the danger depends on what kind of river you’re running, the temperature, and a ton of other factors. In a boat, you’re likely to die if you can’t roll the boat back up and you hit your head / get knocked out, or your boat gets trapped upside down. After you bail from the boat, you could get pinned or caught up in trees, pulled under big rocks that are undercut, trap your ankle in a rock (in shallow water), which then pushes your body underwater downstream, die from exposure / drowning (you wash down the river faster than anyone can get you and just give up the will to live because it’s too cold / you can’t stay above it anymore).
But you can do all that on a motorcycle and still get creamed.
It does require you to honestly assess your ability to say "no" when conditions aren't right.
Basically what I'm getting at is there are activities that are dangerous but some the danger comes from you and others the danger comes from outside forces/other people. (Sure, I guess you could argue that you could just not ride your bike when there's other people on the road, but that's not practical).
A friend is a Navy pilot, and a crash investigator, trust you instruments all the time.
[1] https://www.wikidata.org/wiki/Q999646
[2] https://www.wikidata.org/wiki/Q35627590
[3] https://www.wemjournal.org/article/S1080-6032(03)70564-X/pdf
[4] https://web.archive.org/web/20030323041203/https://www.nhtsa...
I've updated Wikidata to deprecate the incorrect incidence rate from the kayaking paper, and replaced the incidence rate with more up-to-date data from the US BTS which puts it at 0.8 deaths per 100 million vehicle-miles in the US. Using the assumption from the kayaking paper of 100 miles/day being the average distance traveled by car, whitewater sports are therefore 7-8 times more likely to lead to death than traveling in a car.
New query showing more accurate incidence of death rates: https://w.wiki/3Src
Which is one hell of an assumption in case that wasn't obvious.
Even people with absurd commutes tend to have less than 100mi/day weekly or annual averages unless they're doing the same thing on the weekends.
this enables an intelligent choice regarding such water, as well as informed insight regarding how drowning machine deaths mechanistically occur.
basically you have to get past the "boil up region" to avoid what looks like passive water, that will suck you in and keep you under.
This article really struck me, so I shared this with him, along with the video of the Binghamton, NY Susquehanna River Dam accident, which is mentioned in this article. In a light tone I said to him "don't ask why I'm telling you this randomly now, but never go near a low head dam."
He quickly reminded me that I have a family member who died when I was young that drowned. I never knew the details - turns out it was a low-head dam.
It's easy to think that in modern society there aren't many almost unseeable risks like this lurking out in the world.
In some cases the bodies circulate below the dam if decomposition gases produce enough buoyancy. Or the body surfaces miles downriver.
In all but one case I know of, the dog gets out on its own.
Sadly it's taken decades and usually repeated fatalities to prod authorities into action.
Dynamite does the job.
Where the dam is still needed you can raise the downstream riverbed with rocks 4+ feet in diameter and end up with a runnable low hazard rapid.
https://dnr.maryland.gov/fisheries/pages/fishpassage/bloede....
There are other subtleties in 3D as well; some weirs form a downstream-pointing V when viewed from above the dam - these are generally considered safer as the currents will (generally) move you to the middle of the river and downstream where the water is more likely to be escapable - see [1].
Others can form an upstream-pointing V which has the opposite effect where the currents will move you towards the middle of the river but upstream back towards the stopper/keeper/hydraulic.
[1] https://assets.atlasobscura.com/media/W1siZiIsInVwbG9hZHMvcG...
Is there anything you can do if you get caught in one?
Note the path of the blue arrows escaping downstream in the diagram.
I can't find the source but have seen reports where people have been caught in a weir, drowned, and remained spinning in the currents for a couple of days before they're eventually spat out by chance and the bodies are recovered. They've well earned the name "drowning machines".
I have no intention of going anywhere near one of these dams, if I can help it.
Hydrolic power is the ONLY way humans can survive on this planet after all the dead trees are burnt.
If fish not being able to reproduce and people drowning is more important you better be prepared to go back to the 17th century for everything else.
Dams are also becoming less effective as climate change increases drought conditions in areas with dams.
Wind and solar have net negative energy output, meaning the cost of manufacturing the cells/turbine + the electronics, cables and batteries cost more energy than the hardware will generate in it's lifetime.
The tree is the best solar panel + battery and nature invented it, it made all the coal, oil and gas!
Beyond that only hydro and nuclear can help, and you cannot build, maintain or rescue a nuclear plant without dead trees.
So that leaves hydro, even with flooding and drought; it's the only stable "source of progress".
But it's ok I'm used to it and value karma the other way around; by design on this forum low karma is truth and high karma is toxic!
I'm aiming for the lowest karma possible, and I'm going to avoid the high karma people to the largest extent possible and when the HN database leaks everyone can see what's what.
They wont stop me from trying to have a discussion with people that actually have something to say.
EROI for wind turbines is on the order of 20 to 30.
So, no. You're wrong about that.
What is EROI for hidro/thermo/nuclear?
Everything except dead trees and hydro is completely stupid!
ERORI on oil has gone from 100/1 to 10/1 in 100 years.
Could you post some data and/or resources on where you’re getting your numbers? It sounds surprising and unlikely, because large wind turbines can generate a lot of energy over their lifetimes. Ivanpah solar generates about 850Gwh annually and has been running for 10 years, with many more on the horizon. You are sure 8500 Gwh is less that it took to construct? I’m curious about your claim and willing to hear the research. How are you calculating the energy inputs of manufacture? How are you calculating the lifetime outputs?
I tried to Google it and the very first result roundly and soundly counters your claims, and backs it up with real data. https://fullfact.org/online/wind-turbines-energy/
“A 2010 analysis of fifty separate studies found that the average wind turbine, over the course of its operational life, generated 20 times more energy than it took to produce. This level was “favourable” in comparison to fossil fuels, nuclear and solar power.”
And most importantly, is comparing energy in to energy out the right question to ask, and why? If energy in is renewable, then why would it matter how much it takes? With oil, return on investment isn’t even relevant to the question of whether it’s sustainable. We’re using up a non-renewable resource, and when it’s gone, it’s gone. The ratio of energy required to pull oil out of the ground compared to the energy it produces is a red herring.
Also what is the part about cat food about? Sorry I don’t get it. Are you suggesting everything needs to be accounted for up to and including cat food? Or is this a joke about over-accounting for things that aren’t directly related?