Ta'anis 25b: For every Tefach of rain that comes from above, the Tehom (water deep below the ground) rises two or three Tefachim to meet it.

Rashi: One affliction calls to its colleague [Radak - to come upon us. Afflictions are metaphorically called water - "v'Nachalei Veliya'al Yeva'asuni" (18:5).

Malbim: One calls to the other and says "Yomam Yetzaveh Hashem Chasdo" (verse 9) - they scream and thank that Hashem's Chesed is ready to come; He will do open miracles, which are called Chesed.

Rashi: This refers to punishments, which shower on me like flooding water.

Radak #1: Punishments spill on us like water from the roof spills from gutter pipes; it makes noise.

Radak #2: Clouds are called Tzinorim, for they spill water.

Malbim: It is as if conduits above put Hashem's voice on the Tehomos, and the Tehomos call to the waves, and the waves answer in a great noise.

Rashi: They are waves of the sea. The waves went above, and break and fall. Radak - they are a metaphor for afflictions, which You brought on us due to our sins.

Malbim: Yisrael are compared to a ship at sea, and great waves threaten to sink it.