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Joined: Nov 2000
Posts: 866
old hand
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old hand
Joined: Nov 2000
Posts: 866 |
Hiya Bingley - may be able to help here....Well, I'll have a go "off the top of my head" and, if nobody subsequently objects, we'll take it as gospel!
As G'Ted has said, I believe "hydrogeology" is moreso to do with subterranean water, whilst "hydrology" relates to the characteristics of water on the earth's surface.
To grossly simplify the situation, hydrogeologists would either be looking upon subterranean water ("groundwater") as a resource or a nuisance. I'd like the think that the former aspect of water is obvious - all to do with aquifers, the search for them, the estimation of the resource, the recharging dynamics of the aquifer and the exploitation of the resource. As a quick aside, Perth is coming off the driest summer in 30 years; our dams are all but empty, we are only allowed to water our lawns on a roster - and 60% of the supply is being pulled from underground.
Water as a nuisance refers to the fact that an excess of water in the ground reduces the strength of the ground dramatically. Frinstance, the nature, size and quantity of supporting structures (piles etc) for tall buildings is a product not only of the nature of the substrate, but also its water content. Open pit mines and road cuts are the same - the more water present, the shallower the walls must be - and thus (in the case of mines anyway), the greater the expense attributable to waste removal. Whilst vast sums of money are spent dewatering sites ahead of mining, this is less than would need to be spent in earthmoving costs to strip away the waste if the "wet" substrate was being mined. In underground mines slope stability is less of a factor (the openings are much smaller), but water is still treated as a threat as it can flood the operation.
As I understand it, hydrology is moreso to do with how the water behaves on the surface. There is a focus on runoff, flood mitigation, river control etc. What the Dutch have done and the Brits with the Thames are classic examples of the Hydrologists' art.
How'd I go?
stales
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Joined: Sep 2001
Posts: 872
old hand
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old hand
Joined: Sep 2001
Posts: 872 |
Ye with ears listen to stales.But I leaned forward in my chair waiting, hoping, for Brother Stales to mention the object, or more accurately, the lack of objects, of my perverted affection. Maybe he forgot... SINKHOLESSinkholes collapse when the watertable is lowered in places that are underlain by carbonic rock like limestone. Quarrymen pump water from quarries in order to keep the pits dry for mining. This lowers the local water table and so solution cavities, no longer buoyed up by the watermass or clayfill, suddenly collapse. Alabaster, Alabama, until recently, held the worlds record for the deepest and widest collapse. In 1971 a sleeping farmer was awaken by the sound of a muffled Thud. The next morning he walked to his back forty and was met by a 200 foot deep hole, 400 foot wide, with a beautiful lake at the bottom that sounded out at 125 foot deep. He was a Christian man and he said, "Golly". The hole became to be know by hydrogeologists worldwide as the "Golly Hole". I am a caver and cavers love sinkholes. 
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Joined: Oct 2000
Posts: 5,400
Carpal Tunnel
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Carpal Tunnel
Joined: Oct 2000
Posts: 5,400 |
this has been a hot topic in NY as of late. when the WTC was built the edge of Manhattan island a big hole was excavated. to reach bedrock (good old manhattan schist,) they had to go down 70 feet.. at that point, they also reach ground water, and the excavation risked being flooded by the Hudson (North) river.(less than a half mile away.)
so they build a giant retaining wall (called the bath tub) it was anchored to the bed rock, made of waterproof concrete and designed to keep the WTC site free of water.(it is real the opposite of a bathtub, instead of holding water in, it keeps it out--but hey, this is NY, and we are not going to quibble about words here!)
with the collapse of the towers, the south tower collapsed onto the bathtub wall. as the final excavation of the site nears, there have been some near disasters. the damaged bathtub is exposed, as rubble, which has been acting as an earthern dam is removed. the site has come close to being flooded several times.
a complex array of siesmigraphs track movement of the bathtub wall. there are also test going on to check the strenght of the wall-- and each crack is carefully monitored.
meanwhile NY is in the 17 month of a drought. there are water restrictions in place, but twice a day, the streets of lower manhattan are still being washed, as part of a program to control the very fine particles of dust from the WTC.
an excess of water (at WTC) is one problem, the lack of water (in reservois) is an other.
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Joined: Jan 2001
Posts: 13,858
Carpal Tunnel
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Carpal Tunnel
Joined: Jan 2001
Posts: 13,858 |
Dear milum: as a sinkhole fancier, to cross threads, tell us how much sexual fantasy you see in Kubla Khan.
Are the entrances to your spelunking adventures rimmed with curly hair?
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Joined: Aug 2001
Posts: 2,605
Carpal Tunnel
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Carpal Tunnel
Joined: Aug 2001
Posts: 2,605 |
dr. bill, would a like question apply to stales' geological drilling activities?
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Joined: Mar 2001
Posts: 4,189
Carpal Tunnel
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Carpal Tunnel
Joined: Mar 2001
Posts: 4,189 |
How'd I go? --stalesThanks for the insightful geology lesson, as usual, stalesy! I am a caver and cavers love sinkholes.Ain't goin' there...ain't sayin' that.  Your Happy Epeolatrist!
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Joined: Mar 2000
Posts: 6,511
Carpal Tunnel
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Carpal Tunnel
Joined: Mar 2000
Posts: 6,511 |
I am a caver...
Has the word spelunker fallen into disuse?
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Joined: Jun 2001
Posts: 2,636
Carpal Tunnel
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Carpal Tunnel
Joined: Jun 2001
Posts: 2,636 |
Has the word spelunker fallen into disuse?
In the several hours I spent caving with Milo and his bunch of caver friends, not once was spelunker or spelunking used. It was always caver and caving. My thoughts on that are that if I had used the term spelunker, I would have immediately been branded an outsider. So, Milo, am I right that cavers don't use the term?
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Joined: Sep 2001
Posts: 6,296
Carpal Tunnel
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Carpal Tunnel
Joined: Sep 2001
Posts: 6,296 |
And spelunker is such an ugly word. Caver comes out of the mouth from the back of the mouth and then opens up in the middle and then with the "v" becomes, only then, a mouth word. Spelunker is clunky--and sounds kind of silly. Caver moves from back to front--air moving from back to front--like a beckoning hand from inside the cave working its way toward your consciousness. Can't you feel that airy hand asking you to enter? Spelunker doesn't do much other than sound like a stupid rare word--it kind of hobbles about on its syllables--clunketyclunketyclunketyclunk. Sounds like one of those little coal cars in a cave clunking along with spiked-out cargo.
Just my take,
WordWooed
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Joined: Dec 2000
Posts: 13,803
Carpal Tunnel
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Carpal Tunnel
Joined: Dec 2000
Posts: 13,803 |
another "guy thread" and they all agree they don't know what they are talking about!
At least when we don't know what we're talking about, we know it and we admit it.
Classic example of the contrary from women's talk is that little rant about if it had been the Three Wise Women they would have asked for directions.
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