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Comment by Victerius | Hacker News Reader

The Hoover Dam's deadpool level is 895 ft, or 272 m. I am not a civil engineer, but why not build the water intakes (apologies if I don't use the correct terminology) at the bottom of the dam, in order to set the deadpool level at 0 ft? Why build the intakes so high?

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At 0 feet, you will end up with silt being sucked though or accumulating/clogging. Also, the intakes are likely below the stated level, but you need X number of feet above that for water pressure to turn the turbines. Either way, I'm not sure that a retrofit is a feasible option.

> you will end up with silt being sucked though or accumulating/clogging

A big filter at the intake?

That still doesn't solve the pressure part of the problem, and likely makes it even worse.

Filters have to be cleaned, a process that is both expensive and dangerous at the bottom of a reservoir that high. Which is why the better solution is to put the intakes up a bit and allow the bottom of the reservoir to serve as a settlement pool.

You wouldn’t have as much hydraulic head pressure. The lower the intakes the shorter the pen stocks the less power you produce.

The measurements given are from sea level. The deadpool height of 895ft (above sea level) is the output level, where the water dumps downstream. The intakes have to be above this height.

I did some googling since I was also curious and found this stellar article: https://energyeducation.ca/encyclopedia/Hydraulic_head

TL:DR: "Head differences of 100 meters or higher are considered high head. In this type of plant, water travelling through the turbine comes from a significantly higher elevation, meaning that the system needs a smaller volume of water to produce an equivalent amount of energy.[1] These systems generally also require smaller turbines since there is less water flowing through the turbine."

Props for finding a simple yet thorough article explaining many of the terminology used in other responses in this thread. Thank you.

The ideal place for a hydroelectric dam is what's called a slot or "gunsight" canyon. Narrow and high, to create the best conditions with the smallest dam. Dams in wide, relatively flat places like along the Columbia River exist, but they are multi-purpose, built for flood control, irrigation, navigation (with channels and locks), and recreation benefits in addition to hydroelectric.

Because the water needs potential energy to do work.

just like hackers! :-) :D :O

895ft is measured from sea level.

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