Brook of Egypt Called River in Genesis Later Much Less Flow by Time of Moses During Exodus When Ice Age Was Ending

From the days of Abraham (circa 2000 b. c.) until the days of Moses (circa 1500 b. c.), what today is called the Wadi el Amish was described as a River (see Genesis 15: 18), but it began being called just a brook when the Ice Age was ending in the days of the Exodus (see Numbers 34: 5).