The word "head" is a literal translation of the Hebrew word rosh; one meaning is "the main division of a river or principal stream" (compare Genesis 2:10, "And a river went out of Eden to water the garden; and from thence it was parted, and became into four heads"). [Zarahemla Research Foundation, Study Book of Mormon, p. 16]
“I Saw the Head Thereof a Little Way off”
According to Hugh Nibley, for one to be able to see "the head thereof a little way off" is desert scenario. What is even more important, however, is that this desert scenario provides us with a typical case of a river of water coming out of nowhere in the desert [because of underground streams]. Of course, the inevitable tree is growing there; you always find that. And springs come out miraculously, aquifers, etc ["a fountain of living waters"]. Needless to say they are greatly appreciated because they save your life [that is the tree becomes a "tree of life"]. . . . That's the scene of the first psalm, isn't it? The righteous man "shall be like a tree planted by the rivers of water, that bringeth forth his fruit in his season; his leaf also shall not wither; and whatsoever he doeth shall prosper" (Psalms 1:3).
The word ra s is the word for spring and head in Arabic. That's where the stream originates, so when Lehi says, "the head thereof," he is using the proper idiom to designate the head, the beginning of the spring. [Hugh W. Nibley, Teachings of the Book of Mormon, p. 173,176] [See the commentary on 1 Nephi 8:13]