[HN Gopher] The largest US dam-removal effort to date has begun
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       The largest US dam-removal effort to date has begun
        
       Author : pseudolus
       Score  : 37 points
       Date   : 2024-01-11 12:15 UTC (1 days ago)
        
 (HTM) web link (arstechnica.com)
 (TXT) w3m dump (arstechnica.com)
        
       | 11235813213455 wrote:
       | Dams age with damages
        
       | engineer_22 wrote:
       | It's a dam shame
        
       | k12sosse wrote:
       | Was hoping I'd see some Post.10 footage
        
       | londons_explore wrote:
       | How does removing a dam compare with simply opening the gates and
       | releasing all the water?
       | 
       | A dam not holding any water back has far more strength than
       | necessary and will probably last thousands of years.
       | 
       | It's obviously far cheaper.
       | 
       | You get many of the same environmental benefits (lake area no
       | longer flooded, fish can traverse the base of the dam).
        
         | mistrial9 wrote:
         | > imply opening the gates and releasing all the water
         | 
         | would that be step 1 perhaps?
         | 
         | without much thinking about it, I would expect that the shape
         | of the waterway structure may not really match a natural water
         | course at all. For example, quite a lot of the release
         | mechanisms would be at the top third of the dam wall, etc.
         | Probably very specific to each dam?
        
         | markedathome wrote:
         | Switzerland are building a dam next to another dam that can no
         | longer be repaired, B1M have a video going over the method -
         | https://www.youtube.com/watch?v=k0vxzYvIHUk
        
           | ok_dad wrote:
           | That dam also holds back the largest (as far as I recall)
           | pumped hydro storage system in the world. I'm not sure but I
           | think they talk about it in the video you linked if it's the
           | same one I watched a while back.
        
         | dylan604 wrote:
         | The spill way being opened won't release all of the water from
         | a dam. Spill ways are just a type of pressure relief valve to
         | keep the water from destroying the damn. So while it might add
         | more water down stream, it will do nothing for restoring the
         | flooded area upstream of the dam.
        
         | parl_match wrote:
         | First off, that's opening a spillway, and that will still leave
         | a substantial portion of land flooded.
         | 
         | > A dam not holding any water back has far more strength than
         | necessary and will probably last thousands of years.
         | 
         | And, actually isn't true, there's a lot of complicated factors
         | when building a dam, and having a consistent, low lying
         | waterflow (like a river). Depending on the type of damn, soil
         | conditions, etc, it can actually cause disproportionate erosion
         | that will cause the damn to collapse in on itself (in a
         | surprisingly short time frame, under a decade even).
         | 
         | So, engineers will sometimes do what you suggested when it's
         | feasible. But, it's not always.
        
         | pengaru wrote:
         | There aren't gates at the base of any large dam. The only way
         | to discharge the artificial lake behind a large dam is via
         | destruction AIUI.
         | 
         | It will deteriorate with age and eventually break in an
         | uncontrolled/unplanned manner anyways.
         | 
         | At least this way you tear it down gracefully with a gradual
         | discharge of the water, and enable restoration of the
         | environment/salmon breeding etc.
        
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       (page generated 2024-01-12 23:00 UTC)