A verb glossed “well up” in the Qenya Lexicon of the 1910s derived from the root ᴱ√QEL+U, a variant of ᴱ√KELU (QL/76).
Early Quenya
qelu
noun. well, spring, source
qelu-
verb. to well up
There are more words but they are from Tolkien's earlier conceptional periods. Tolkien likely changed these words as he evolved the aesthetics and completeness of the languages. You may even find languages that Tolkien later rejected. Do not mix words from different time periods unless you are familiar with the phonetic developments.
Below: Tolkien's Late Period (1950–1973). These are from Tolkien's late conceptual period — his most settled forms of the languages. Prefer these over the earlier ones above when composing new text.
A noun appearing as ᴱQ. qelu “well, spring, source” in the Qenya Lexicon of the 1910s, derived from the root ᴱ√QEL+U, a variant of ᴱ√KELU (QL/76). It also appeared with the gloss “well, spring” in the Poetic and Mythological Words of Eldarissa (PME/76).
Neo-Quenya: Related words ᴱQ. qelume “source, origin” and ᴱQ. qeluva “original” indicate this word could be used for the “source” of things beyond just water. As such, I think this word might be salvaged in Neo-Quenya as ᴺQ. celu “source, origin”, from the later root √KELU. The form quel- can’t be retained, as this means “fade” in Tolkien’s later writings, and the abstract form celumë can’t be used, as this means “flowing”.