John W. Gregson on the flood from the mouth of the serpent
In John W. Gregson’s interpretation of Revelation 12:15, 144,000 Jews flee across the desert pursued by a turbulent flood of water that threatens to drown them. Apparently Gregson believes that literal water is meant. The water is absorbed in the desert sand. Gregson wrote: 
15 – 17 To try to stop Israel from fleeing, the Devil cast out of his mouth water like a flood after the woman, that he might cause her to be carried away by the flood (potamophoreton from potamos + phero – moving river; rushing stream). And the earth helped (eboethesen from eboetheo – rescued; succored) the woman by opening up her mouth and swallowing up the flood which the dragon cast out of his mouth. And the dragon was angry (wroth) with the woman and went out to make war with the remnant (loipon from loipos – the rest) of her seed who keep the commandments of God and have the testimony of Jesus Christ. Following the work of Satan so far; he is cast out of heaven (Revelation 12:7 – 9), he opens the abyss and releases the Beast (Revelation 9:1, 2), he breaks his promise with Israel (Daniel 9:27b) and invades the temple (II Thessalonians 2:4), and now comes to the desert in pursuit of Israel (Yeager, p. 219).
To what place will Israel (the woman) flee? Many think that the Rock City of Petra is the logical place. It is according to Unger, “a notable fortress and stronghold. This Transjordanian high place has been excavated…in the Old Testament (it is called) Sela, the capital of Edom, between the Salt Sea and the Elamitic Gulf (II Kings 14:7; Isaiah 16:1)” (p. 852). It is located south of the Dead Sea and is known as a mighty stronghold which can be entered in only one way through the Siq which is a narrow passageway between two high rock walls. A dramatic picture is presented in these verses, “144,000 Jews fleeing fearfully across a desert with a turbulent flood of water in pursuit. The cries of the people reverberate among the rocks and echo across the desert. The earth hears and helps. The desert sands absorb the water. Satan, in frustration, mobilizes the Gentile armies against the Hebrew Christians in the world…Satan will be frustrated because his attempt to drown the fleeing Jews will have failed. If he succeeded, the Messiah now about to leave His throne in the glory and return to take His place of David’s throne on earth, would be a King of the Jews without a kingdom people. It is therefore inevitable that the attack upon the 144,000 will fail. Satan, unable to destroy the woman, will go away in frustration to other hellish activity” (Yeager, p. 220 – 222). Satan can and will be overcome but only by the power of the blood of our Savior and by the sacrifice of the Son of God Himself.
In my opinion the flood of water from the mouth of the serpent in John’s prophecy is a metaphor, that represents a flood of flawed interpretations of scripture and prophecy that causes desolation in the church. The figure of the earth opening her mouth, and swallowing up the flood, contrasts with the dragon’s attempt to devour the woman’s child in verse 4. The land, the place prepared by God for the woman, represents the spiritual inheritance of the saints, including the knowledge of God, and the truth, and understanding prophecy. The truth swallows up the serpent’s flood. One of the promises Jesus gave to his disciples was that the Spirit would guide the saints into all truth. [John 16:13]
1. John W. Gregson. Revelation Commentary. 2001