this post was submitted on 24 Jul 2023
1729 points (98.7% liked)
Mildly Interesting
17346 readers
2 users here now
This is for strictly mildly interesting material. If it's too interesting, it doesn't belong. If it's not interesting, it doesn't belong.
This is obviously an objective criteria, so the mods are always right. Or maybe mildly right? Ahh.. what do we know?
Just post some stuff and don't spam.
founded 1 year ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
Why only 21 inches? Soil temps aren't stable until like 6 feet down, and then it's closer to 12 C.
That is the deepest depth I could find being actively tracked on the website I ended up on. I did not wanna do a deep dive into "great" average soil temp data lol. If you have a good source of data I will gladly change my comment to include the updated numbers. I wanted to say the average soil temperature at depth is ~50-55 degrees F, but I hopped online to make sure that was not a number that I know to be true due to where I live. Good to know that its roughly 6 feet where it stabilizes
If you go down deep enough the earth temperature is stable at 12 C. But I'm pretty sure that's like thousands of feet down. Geothermal rigs drill 500+ meters (1600 feet) down. Having a hard time finding a source on the stable earth temp though.
I mentioned 6 feet because it's well below the frost line where I am, but I guess in that part of Iran they probably don't have to worry about that.
Mostly I was just wondering if you had found something on how deep those waterways were actually built.
Yeah thats exactly the issue I ran into. I started googling stable soil temp to confirm what I thought, and rapidly ran into a lack of answers lol. Any data I could find for free on websites didn't seem to go very deep.
In terms of depth of the Qanats, yeah I was wondering the same. Without any modern tools I'm not sure how deep they would be willing to dig out (although I bet it's easy digging in Iran, likely sand/dry dirt vs. clay and sopping wet boggy soil).
I am at work but I'll see if I can dredge up info on Qanat depth