Shall not the land...? — The rendering should be, The whole of it rises as the Nile, surges and subsides (or sinks) as the Egyptian Nile. The solid land shall rise up in earthquake, like the Nile that ascends twenty feet in the time of its inundation, and then subsides.
Related Commentaries of Amos 8:8
Amos 8:8
8 Shall not the land tremble for this, and every one mourn that dwelleth therein? and it shall rise up wholly as a flood; and it shall be cast out and drowned, as by the flood of Egypt.