When I was a child I heard about underground rivers and imagined them as being actual rivers running through underground tunnels. However, now I’m beginning to wonder if they mean that the water sort of filters along in limestone or something. 1)Does it or are there real rivers under ground in tunnels? And 2) What do they mean by ground water? Does the rain go into the earth and then wind up at a level of water called the water taable or ground water? But 3)how is it held? Does the water table mean wet mud down there or maybe wet rock? 4)This is the level that wells tap, I assume, and so I ask how can we be drinking this water when it has filtered through microbe and pesticide etc. polluted ground? Yet I drink well water from my well all the time. What if you are fixing your car and some oil etc. falls to the earth and then goes down into your well water? What of all the seepage down from enormous garbage dumps that are all around here, doesn’t all that polluted water end up in my well?
IIRC there are a few ‘underground’ rivers as you imagined as a kid depending on how you define it. There is one that is a tourist attraction in upstate NY called IIRC natural stone bridge. The river runs underground for maybe 200 ft - but don’t hold me to it, it was a long time ago.
Most water underground is basically as you put it, mud or water seaping through cracks in rocks. Usually this flows in terms of inches per week.
When I was a caver, I saw a couple of underground streams - not rivers, but fast-flowing and deep streams about 4 feet wide by 1-3 feet deep. They did not have any known entrance or exit aboveground. It is not a big stretch to imagine a much larger river.
In fact, in the history of the connecting between Mammoth Cave and the Flint Ridge cave system, I believe their was a large river called “Hanson’s Lost River” or something that formed the crucial connection.
As for your comments on well and acquifer water…typically, microbes are not a problem. I don’t think there are many pathogens that survive that far down, although there are algaes and such. And seepage of chemicals into the water is a serious problem, although with the rate that water percolates it often takes some years before the surface chemicals make it down to the acquifer. However, some of it does eventually get down and into the acquifer. And then you are in trouble.
Didn’t you ever see the movie Broken Arrow? There was an underground river in that movie.
Seriously though,
I hiked into ‘lava cave’ that was on JeJu island off the Southern coast of South Korea. The entire island is obviously volcanic-ly formed.
This cave was huge. We hiked in what seemed like a couple of miles and in places it must have been 10 meters in diameter. Like a very long, not-so-straight cylinder. This was not into a hillside. It was simply under the ground. Relatively flat ground. If it happened to cross under a river, and then the bottom of the river colapsed, you would have exactly like what was in the Broken Arrow movie only on a grander scale. Based on seeing this lava cave, I am sure there must be actual rivers under ground somewhere in the word where the water simply flows.
Other than that, I’ve seen caves where was plenty deep water, but no noticable movement of it.
I’ve been to Natural Stone Bridges that K2Dave is speaking, there is actually two of them. Both are just your normal above ground streams that travel underground for a period of time. One of them even has a short rowboat rided involved and some legend (unproven IIRC) about a local having a secret entrance to his house from there along with some story of hidden gold.
I seem to recall a story National Geographic did a while back about the inerconnected spring system down in Florida that was connected by underground rivers.
As a follow-up to my previous post, and to try and jog Dave’s memory…
The National Geographic article “North Florida Springs” was in March of 1999.
Natural Bridge Caverns is in Natural Bridge, NY and is the one with the boat ride on the Indian river.
Natural Stone Bridge and Caves is in Pottersville, NY and is more impressive with potholes and more caves and holes to exlore than the one in Natural Bridge.
Water seeps through the soil at a rate of one inch per 75 years. This is in normal, deep, semi-sandy soil. There’s not much danger of oil seeping into your groundwater, unless it is stored in an unproperly sealed landfill and your groundwater is very shallow. Spilling oil on your lawn won’t kill you.
There are some actual flowing rivers conected via cave systems that go throw rock channels, but they are rare; rare enough to become tourist attractions.
Most ground water is found in the form of patches of water saturated gravel-like material buried under the ground. Where it’s found it doesn’t sink miles down because there is some kind of confining layer in the ground like a big layer of clay or bedrock that stops it from sinking further down. Surface water and precipitation will filter down and collect in these areas and then percolate (rather than flow) downhill underground at different rates and over different distances depending on the geology of the area.
Wells are usually drilled down into these sandy areas or fractured rock zones because there is enough pore space for water to collect there, which we can suck out.
You can envision it as taking a 5-gallon bucket, filling the bottom 1/3 with packed clay, the next 1/3 with gravel, and the top 1/3 with regular dirt. Then take a watering can and sprinkle in a couple litres of water. This “precipitation” will filter down through the surface dirt, and collect in the gravel layer since it won’t percolate much into the clay. Now take a long straw and push it down into the bucket - you’ll have go far enough down to reach the water table, but too far and you’ll be trying to suck up essentially dry clay. There is your well.
Now drop 1ml of food coloring (contamination) onto the surface dirt and sprinkle again. You won’t suck out any colored water… drop a cup of food coloring on the surface and you will.
Garbage dumps usually have to have some kind of impermiable layer beneath them like a liner or a few feet of clay so that the water that filters down through them doesn’t go anywhere - there should be water monitoring stations and boreholes dug around them to make sure. Not all dumps have this though, and sometimes the water finds a way out and ends up in the water table… if you’re close enough to draw this contaminated water up from a well, you’ve got a lawsuit on your hands.
How far down different chemicals travel depends on their nature. DNAPLs*, including many chlorinated solvents like trichloroethylene (TCE), perchloroethylene (PCE) and dichloroethane (DCA), PAHs, and PCBs will sink deep down into the aquifer and sit near the bottom.
LNAPLs** like petroleum and other refined hydrocarbons such as benzene, toluene, ethyl benzene, and xylene will usually just saturate the soil above, and if they make it down to the water table will hang in pools near it’s surface.
Water traveling at 1" per 75 years through soil is highly variable since there’s really no such thing as “normal” soil; it totally depnds on the geology of the area and amount of precipitation. If it took 75 years X 6" for the water to get to the bottom of my flower pots, I’d have a lot of dead plants. If you’re in a dry area full of clay where it rains 1/2" a year, it’ll take a while for water to go anywhere. If you’re in the sandy tropics where it rains 6’ per year, that water has to go somewhere.
- DNAPL = dense non-aqueus phase liquid
** LNAPL = light non-aquaeus phase liquid
There are, as noted above, true running streams underground, associated in the main with Karst topography. Simply put, that’s caves; more rigorously it would be described as the environment created by water driven erosion associated with carbonate, or water soluble, bedrock.
Water also moves, as has also been noted, through subsurface rock bodies. I don’t know where the one inch every 75 years offered above comes from for water seeping through soil - I’ve never heard it before. Porosity and permeability are the two parameters that would govern the rate at which fluid can move through lithologic media, and the relationship is described by Darcy’s Law. What follows is one simple formulation thereof:
flow volume/time = area x velocity
The site I linked will take you into more detail. Aquifers would be a great subject to research for more on this. Suffice to say that water does move underground, rarely in “streams” and more often in sufficiently porous and permeable strata such as, in the near surface, gravel and sandstones, and deeper, in sandstones and, to some degree, in fracture zones in shales and carbonates - most predominantly in sandstones.
Just for an empirical snapshot on the rate of flow subject, let me tell you that it is not at all uncommon for a deeper sandstone to give up 20,000 to 40,0000 gallons of water through a [sup]16[/sup]/[sub]64[/sub]" choke in 24 hours. Think about how quickly a brick wall absorbs the discharge of a garden hose.
Would this article have been on the Wakulla Springs mapping expedition? I know that they were affiliated with the Wakulla 2 project.
http://www.wakulla2.org/index.htm (kind of a crappy site, sorry)
I know nothing about geology, but if there were ever a canadate for an underground river, then the Wakulla region cave system sounds like one to me. The volume of water coming out of this spring is amazing. (over 400,000 gallons per minute and in 1973, was recored at twice that) So is the size of the tunnel/cave system it flows from. (miles of it, most of it uncharted, probably due to the excessive depth and human limitations)
It’s a pretty neat area when it comes to springs, caves and swimming holes. Then again, I grew up there, so I’m biased. 
Cite, please.
I’d like to see some sort of citation for that, too.