The Holy Spirit has been gracious to reveal the meaning of His symbolic communication over the years. In faith, I speak the part I understand.
1 Corinthians 13:12
Amplified Bible, Classic Edition (AMPC)
12 For now we are looking in a mirror that gives only a dim (blurred) reflection [of reality as in a riddle or enigma], but then [when perfection comes] we shall see in reality and face to face! Now I know in part (imperfectly), but then I shall know and understand fully and clearly, even in the same manner as I have been fully and clearly known and understood by God].
According to Webster's online dictionary, backflow is defined as "a flowing back or returning especially toward a source." The Lord is calling us to return to Him, doing the things we know He has commanded and steering clear of the things we know He has denied. The only way to determine the difference between right and wrong is to consult the Source, God. Intimate, one on One communication is the key.
The second part, "Tidal Wave" is well known in the physical. I remember the horrible tidal wave (tsunami) which swept over coastal Japan in 2011, causing widespread death and destruction. The "Tidal Wave" that the Lord is referring to also has devastating destructive power. Those of us who refuse to return to the Source and/or who hold onto things which we know are sinful or not permissible, may incur the destructive force of this spiritual Tidal Wave. The consequence of sin is painful. God allows us to choose, choose wisely.
I really don't know if this "Tidal Wave" will affect people simultaneously on a large scale or if each of us will experience our own unique Wave, but what I do know is clear...
stop holding onto sinful activities, impure thoughts, coarse talk! Love your neighbor as you love yourself. Don't get caught up in the twisted reports inspired by the evil one to induce us to fear those who are not like us! Realize, that we are not our own, but that we have been bought with a price. Jesus gave Himself for us. God, made man, His Spirit is in control. To stand against Him is a futile pursuit. His fierce love will draw our hearts back to Him.
Holy Spirit, empower us in Your Grace. Cause us to hear You. Empower us to obey You. Give us courage in the midst of trials and Peace in the midst of storms. Be our Helper as You have in the past. You are our refuge and our strength, a present help in times of trouble. Cause us to come back to You, our Source, to release our grasp in things which ultimately harm us. Let our gaze be shifted to eternal things, which places the appropriate value on temporal things. All for the glory of One, Who was and is and is to come, Jesus! AMEN!