Hugh Nibley says that when Lehi dreams of a river, it is a true desert river, a clear stream a few yards wide with its source but a hundred paces away (1 Nephi 8:13-14) or else a raging muddy wash, a sayl of "filthy water" that sweeps people away to their destruction (1 Nephi 8:32, 12:16, 15:27). In the year A.D. 960, according to Bar Hebraeus, a large band of pilgrims were returning from Mekka and "encamped in the bed of a brook in which water had not flowed for a long time, and during the night, whilst they were sleeping, a flood of water poured down upon them all, and it swept them and all their possessions out into the Great Sea, and they all perished." Even a mounted rider if he is careless may be caught off guard and carried away by such a sudden spate of "head water," according to Doughty. One of the worst place for the gully-washing torrents of liquid mud is in "the scarred and bare mountains which run parallel to the west coast of Arabia; . . . the rainstorms beat against this long ridge and produce almost in a moment raging torrents--the Arabic sayl, spate--which sweep away all obstacles without warning and with loss of life of man and cattle." This was the very region through which Lehi traveled on his great trek.
The springhead and the sayl, such are the two and only types of "river" (for he calls them rivers) known to the desert Arab. [Hugh Nibley, Lehi in the Desert, F.A.R.M.S., p. 45]