GaryQWA
Silver Member
- Joined
- Jun 4, 2005
- Messages
- 110
- Location
- Wherever I park the motorhome
- Tractor
- So far only 3 OTR dual axel Peterbilts and one Freightliner. :)
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When many people talk about wells they mention underground river or stream but that's not true. Either the water is coming from water bearing sand and gravel or from porous rock or cracks and fissures in rock or from between layers of rock as in a rock bore well that has no screening and is not fully cased as a sand and gravel well has to be.
Gary Slusser )
It's sort of true, at least in some areas. They are really called aquifers. The water does travel, but very slowly. In our area it's something like 1/4 mile per year if I remember correctly. It is, as you mention, mostly porous rocks and cracks.
I'm about 30 miles from the Pacific ocean, and I'm told water in the aquifer does flow there, but obviously it takes a long time. There is a boundary point about 6 miles north of me where the aquifer flows north to the SF bay rather than out to the ocean. )</font>
Actually the definition of "aquifer" is: An underground layer of earth, gravel, or porous stone that yields water.".
All wells that produce water are into water bearing strata and thereby called an aquifer. Otherwise the well is dry. And it is true that most groundwater moves, but very little to none can be referred to as a stream or river of underground water. Or underground lake or some such. /forums/images/graemlins/smile.gif
BTW, any stream or river, lake or pond that never goes dry in the worst drought, is a gaining 'stream' meaning the groundwater is feeding it. Likewise, any that go dry are losing 'streams' meaning they feed the groundwater. And the normal level of all is the local water table. Groundwater is from the saturated zone down meaning that all pores are water filled. Above that zone is the unsaturated zone, containing both air and water, which expands and contracts with precipitation as the water table and groundwater rises and falls. The static water level in the well is the water table of the area influenced by the well.
Groundwater movement is like electrical current creating flux. Groundwater flows as current does in flux. Some will come up in the bottom of rivers, lakes etc. and some will go to the oceans. Some will not move at all and the rest moves very slowly on a large regional basis. 'er at least that's the way it was explained to me.
One other thing since we're all here... as a well is used, meaning water is taken from it, there is a cone of depression that forms around the well. The cone is an area where the water table falls toward the pump inlet and if there is contamination within that area, is is very likely to enter the well. Hence wellhead protection zones.
Here is a drawing from the EPA concerning some of this:
http://www.epa.gov/seahome/groundwater/src/cone.htm
And for anyone that really wanted to git in over yer head! (scroll to the bottom)
http://people.hofstra.edu/faculty/j_b_bennington/121notes/groundwater_flow.html
Gary Slusser
When many people talk about wells they mention underground river or stream but that's not true. Either the water is coming from water bearing sand and gravel or from porous rock or cracks and fissures in rock or from between layers of rock as in a rock bore well that has no screening and is not fully cased as a sand and gravel well has to be.
Gary Slusser )
It's sort of true, at least in some areas. They are really called aquifers. The water does travel, but very slowly. In our area it's something like 1/4 mile per year if I remember correctly. It is, as you mention, mostly porous rocks and cracks.
I'm about 30 miles from the Pacific ocean, and I'm told water in the aquifer does flow there, but obviously it takes a long time. There is a boundary point about 6 miles north of me where the aquifer flows north to the SF bay rather than out to the ocean. )</font>
Actually the definition of "aquifer" is: An underground layer of earth, gravel, or porous stone that yields water.".
All wells that produce water are into water bearing strata and thereby called an aquifer. Otherwise the well is dry. And it is true that most groundwater moves, but very little to none can be referred to as a stream or river of underground water. Or underground lake or some such. /forums/images/graemlins/smile.gif
BTW, any stream or river, lake or pond that never goes dry in the worst drought, is a gaining 'stream' meaning the groundwater is feeding it. Likewise, any that go dry are losing 'streams' meaning they feed the groundwater. And the normal level of all is the local water table. Groundwater is from the saturated zone down meaning that all pores are water filled. Above that zone is the unsaturated zone, containing both air and water, which expands and contracts with precipitation as the water table and groundwater rises and falls. The static water level in the well is the water table of the area influenced by the well.
Groundwater movement is like electrical current creating flux. Groundwater flows as current does in flux. Some will come up in the bottom of rivers, lakes etc. and some will go to the oceans. Some will not move at all and the rest moves very slowly on a large regional basis. 'er at least that's the way it was explained to me.
One other thing since we're all here... as a well is used, meaning water is taken from it, there is a cone of depression that forms around the well. The cone is an area where the water table falls toward the pump inlet and if there is contamination within that area, is is very likely to enter the well. Hence wellhead protection zones.
Here is a drawing from the EPA concerning some of this:
http://www.epa.gov/seahome/groundwater/src/cone.htm
And for anyone that really wanted to git in over yer head! (scroll to the bottom)
http://people.hofstra.edu/faculty/j_b_bennington/121notes/groundwater_flow.html
Gary Slusser
