Adam Clarke on Ezekiel 30:12

I will make the rivers dry - As the overflowing of the Nile was the grand cause of fertility to Egypt, the drying it up, or preventing that annual inundation, must be the cause of dearth, famine, etc. By rivers, we may understand the various canals cut from the Nile to carry water into the different parts of the land. When the Nile did not rise to its usual height these canals were quite dry.