How does John Keats use language to describe the Nile?

Keats's poem “To the Nile” is, as its name suggests, addressed to the large river that flows through Egypt. The poet makes use of several literary devices to convey a sense of its character and describe its features. Keats begins with a metaphor, describing the Nile as “son of the Moon-mountains African!” Here, Keats is referring to the “Mountains of the Moon,” a legendary mountain range at the source of the Nile in east Africa. By stating that the river is the “son” of these mountains, he expresses the idea of the river emerging out of, or being produced by, these mountains. (As a side note, the Mountains of the Moon were never found, although scholars have put forward a number of candidates for the title). Another metaphor follows: “Chief of the Pyramid and crocodile!” This suggests the Nile is all-powerful in Egypt, ruling over all aspects of life. Keats employs descriptive terms to convey the sense of the Nile as creating or helping to sustain life. It is “fruitful” and a “nurse.” The river is then placed in sharp contrast to the barren surrounding land: “A desert fills our seeings inward span.” Keats concludes his poem by referring to the “ignorance that makes a barren waste of all beyond itself.” Here, he is pointing to the way the barren land is ignorant of (doesn't know) the Nile and its “fruitful” qualities. He finishes by comparing the Nile to “our rivers,” by which he means those in Britain and Europe, writing, “Thou dost bedew Green rushes like our rivers, and dost taste The pleasant sunrise. Green isles hast thou too, And to the sea as happily dost haste.”
http://www.poetryatlas.com/poetry/poem/65/to-the-nile.html