Question for the hydrologists here
 

Mrs WD and I are on our biannual visit to her homeland - Tennessee. This week we are in a cabin on the pointy end of Sugartit Mountain, just up the holler from Fleshy Bottom. :D

So my question is:
We are on the very tip of this mountain on a flat pad that is at most 150 feet across, and it is at least 500 feet down to the nearest ledge on all sides. Yet there is a water well here. How does an underground water table develop at the top of a mountain?

I would think a very long pipe is involved.

Two men are peeing off a bridge.

One is from Ohio and one is from Tennessee. The one from Ohio says "Man, this water is cold."

The one from Tennessee says "Yeah, and it's deep too.

It's called a Perched Water Table.

Water soaks through permeable layers until it hits an impermeable layer then accumulates.

Geology of the subsurface is not always predicted by topography.

I'm a licensed hydrogeologist, so I know a bit about this stuff. Do you have data on the well? How deep is it? What's the depth to water? At what depth(s) is it screened?

There's groundwater under valleys and hills. It's just deeper to water if you're on a hill.

Another interesting fact: In San Francisco, they have some old municipal water wells right on the beach. Fresh water is less dense than salt water, so it "floats" on top of the salt water from the ocean. The higher elevations on land push the fresh water out to sea. There's a wedge of fresh water over the salt water. Of course, if you drill deep enough you will get into the salt water. And if you pump too much, you will raise the interface between the two.

This could be true. But not necessarily. Groundwater is very complicated.

He asked, "How does an underground water table develop at the top of a mountain?"

While he may very well not have a perched water table but rather a very deep well my answer was still valid for that specific question.

How deep can a water we'll be? I don't see how there could be an aquifer up here that was supplied from the top. There isn't enough area for water to fall on. Between the cabin and the concrete parking pad there aren't more than a couple of hundred square feet of uncovered soil. If water isn't being pushed up from the bottom it has to have a heck of a deep well.

It's probably a deep well.

But water has been falling out of the sky for millions of years. Long before the structures had been built.

Could be a really big pocket of water that's been accumulating and trapped for eons.

Try not to think about it but it's probably dinosaur piss.

Good thing we bring our own drinking water!

How long is the rope? Does it take an hour to retrieve the bucket?

Sugartit and Fleshy Bottom. SmileWavy
http://forums.pelicanparts.com/uploa...1493479991.jpg

I've had hundreds of wells drilled most around 200', but some much deeper, even in the same vicinity of shallower wells. Recently did a home on a ridge, 100' above the road, and the well wasn't excessively deep.

The well at my last house was 300 feet deep

Yes, I like to tease Mrs WD about where she's from . :D
She just rolls her eyes.

Our last well just to irrigate the lawn was 225'.

In your first post, you first say you are on the "tip" of a mountain, then on the "top." I'm assuming "tip" is a typo. I'm not a hydrologist, but I'd think you'd have to consider the bedrock morphology below sediment the cabin's located on. I'd think it would be possible for it to form basin and fissure structures that could hold and channel water. It would be interesting to do some witching/divining around the cabin area to see where indications for water are. When I witched the area for my house, I only came up with one decent location for water. Luckily it was rated at 40 gpm after the well was done.

A well on my rural property dug back in the 30s is 24' deep...with 18' of water in it....that's the deep well...another is 15' deep. My spring fed ponds love it :)

Third guy comes along and says "It's got a muddy bottom, too."

Maybe the spinning of the earth pushes the water to the top of the mountain.

Nah. That's stoopid.

There's magnets. That's it. Magnets.

Tip, top? This space is little more than a 2 room cabin and a place to park a truck on the top of a mountain. Everything within a few feet of us is steeply down -like hundreds of feet.
It seems like a tip to me, but it might be a top.