Socks,
Now to answer your query about the interpretation of "earth" in Rev. 12:16...
It seems as though you may be alone, or at least one of the very few, that adhere to the actual earth in this passage...
Let's look at some established commentaries on the verse:
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1). Adam Clarke Commentary
Verse 16. The earth helped the woman
"Nothing, and indeed," as Bishop Newton excellently observes, "was more likely to produce the ruin and utter subversion of the Christian Church than the irruptions of so many barbarous nations into the Roman empire. But the event proved contrary to human appearance and expectation:
the earth swallowed up the flood;
the barbarians were rather swallowed up by the Romans, than the Romans by the barbarians; the heathen conquerors, instead of imposing their own, submitted to the religion of the conquered Christians; and they not only embraced the religion, but affected even the laws, the manners, the customs, the language, and the very name, of Romans,
so that the victors were in a manner absorbed and lost among the vanquished."
MY COMMENT: The waters represents the enemies of Christians in this commentary, and the earth is representative of the Romans accepting Christianity. I'm not saying this is a correct interpretation, only making a point about the meaning of earth and water.
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2). Barnes' Notes on the New Testament
Verse 16. And the earth helped the woman.
It was enabled to avoid the direct attacks of the enemy, and when he attacked it in a new form, a new mode of intervention in its behalf was granted, as
if the earth should open and swallow up a flood of water. We are not, therefore, to look for any
literal fulfilment of this, as
if the earth interposed in some marvellous way to aid the church. The sense is, that, in that state of obscurity and solitude, the Divine interposition was manifested, in an unexpected manner, as if when an impetuous stream was rolling along that threatened to sweep everything away, a chasm should suddenly open in the earth and absorb it.
During the dark ages, many such interventions occurred, saving the church from utter destruction.
Over-flowing waters are often in the Scriptures an emblem of mighty enemies.
Psalms 124:2-5, "If it had not been the Lord who was on our side, when men rose up against us; then they had swallowed us up quick, when their wrath was kindled against us: then the waters had overwhelmed us, the stream had gone over our soul: then the proud waters had gone over our soul."
Psalms 18:16, "He sent from above, he took me, he drew me out of many waters."
Jeremiah 47:2, "Behold, waters rise up out of the north, and shall be an overflowing flood, and shall overflow the land,"
etc. Compare Jeremiah 46:7-8.
Jeremiah 46:7-8 (New International Version)
7 "Who is this that rises like the Nile,
like rivers of surging waters?
8 Egypt rises like the Nile,
like rivers of surging waters.
She says, 'I will rise and cover the earth;
I will destroy cities and their people.'
MY COMMENT: Hold on... the waters represent mighty enemies? The earth represented a Divine manifestation? Again, I'm not saying this is a 100% correct interpretation, only making a point again about the meaning of earth and water. 
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3). John Darby's Synopsis of the New TestamentHe (
Satan) seeks to pursue; wings he has none: but he uses
a river,
the movements of people under the influence of special motive and guidance, to overwhelm the woman. But
the earth,
this organized system in which men live, swallowed the waters up. This influence was in vain -was not met by an army, a counter-power, but was nullified.
MY COMMENT: Time out... Did John Nelson Darby (the father of modern dispensationalism and literal interpretation) say that the waters represent the movements of people and didn't mean an actual river? And, did he say that the earth represents an organized system in which men live and didn't mean an actual chasm in the earth? Did he say that there was some "organized system" in the earth ready to soak up that river that was spewed out? 
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4). The New John Gill Exposition of the Entire BibleAnd the earth helped the woman…
...of opinion that the barbarous nations are in this also designed, who embracing Arianism, and the corrupt religion, where they came, by which they were, in, some measure, mollified and reconciled to the Christians, did not seek to root them out, and destroy them, as Satan hoped they would; but since they themselves,
with the Mahometans,
are meant by the flood,
the earth must be interpreted of the corrupt and antichristian church, the idolaters which sustained the force of this inundation, and for some time repelled it, and so secured the true church;...
...and the
Turkish inundation was a scourge upon the antichristian party:
so that it was the earth, or earthly part of professors, the idolaters, that bore the fury and force of this flood, and broke it off from the church.
MY COMMENTS: Ouch! We see it again... The rivers are enemies, and the earth is a group of people, or idolaters in this case!!!, that sustained the flood. Are these idolaters the Mahometans (Muhammad - Muslims) that soak up the spewing of Satan?
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5). David Guzik's Commentaries on the BibleThe earth opened its mouth and swallowed up the flood which the dragon had spewed out of his mouth: This passage also describes God's ultimate protection of Israel from the fury of Satan and his antichrist in the great tribulation.
i. As it says in Isaiah 59:19, When the enemy comes in like a flood, the Spirit of the LORD will lift up a standard against him.
MY COMMENTS: Again, the flood is the enemies... The earth is representative of God's ultimate protection.
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6). Commentary Critical and Explanatory on the Whole Bible - Robert Jamieson, A. R. Fausset and David Brown
The earth, as contradistinguished from water, is the world consolidated and civilized.
MY COMMENTS: The earth represents the peoples of the world...
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7). People's New Testament
The earth helped the woman. In some way the flood of persecution was so hindered that it failed to accomplish the object. I believe this refers to the hindrances often interposed by secular powers to stay persecution. The Hussites protected themselves under Zisca by force of arms; the German princes protected Luther; the edict of Nantes gave French Protestants a rest.
These were times when "the earth" drank up the flood.
MY COMMENTS: How can this be... The earth drank up the floods of persecution. Say it isn't so...
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8 ). John Wesley's Explanatory Notes
Verse 16. But the earth helped the woman - The powers of the earth; and indeed she needed help through this whole period. "
The time" was from 1058 to 1280; during which
the Turkish flood ran higher and higher, though frequently repressed by the emperors, or their generals, helping the woman. "
The" two "times" were from 1280 to 1725. During these likewise
the Turkish power flowed far and wide; but still from time to time the princes of the earth helped the woman, that she was not carried away by it. "
The half time" is from 1725 to 1836. In the beginning of this period
the Turks began to meddle with the affairs of Persia: wherein they have so entangled themselves, as to be the less able to prevail against the two remaining Christian empires. Yet this flood still reaches the woman "in her place;" and will, till
near the end of the "half time," itself be swallowed up, perhaps by means of Russia, which is risen in the room of the eastern empire.
MY COMMENTS: Wow... Wesley had his finger pointing in the right direction. Do you think he was that far off base with pointing to a people group as being "the earth" that swallows up the flood?
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To summarize: You seem to be the one that is going astray from nearly all logic and apocalyptic interpretation by assuming that this is going to be some single event that actually going to deal with a physical river or water supply and not Israel's enemies.
I think it will be plain when it happens. Maybe something to do with Israels water supply coming from the Golan Heights, maybe not. Maybe that giant dam built on gypsum in Iraq, maybe not. I do think it is a future event, and I've yet to hear reasoning from you to change my mind.
Yes, I do believe the Muslims are helping to swallow up the torrent. But, then again, the flood continues to grow and the Muslims continue to grow until the final showdown. There have been many great theologians in history that understand symbolism and use the representation of symbolism when necessary to bring out the meaning of a verse. All of them agree on the concept of floods and rivers being the enemies of Israel and God's protection over Israel by people groups on the earth.