Hey Dan144, the word construction you seek might best be created rather than dug up...

pluviates: verb
ex. ...upon measured release pent up rainwater in the reservoir pluviates the thirsty city.

pluvial (adj.)
1650s, "pertaining to rain," from French pluvial (12c.), from Latin pluvialis "pertaining to rain, rainy, rain-bringing," from (aqua) pluvia "rain (water)," from fem. of pluvius "rainy," from plovere "to rain," from PIE root *pleu- "to flow, to swim" (cf. Sanskrit plavate "navigates, swims;" Greek plynein "to wash," plein "to navigate," ploein "to float, swim," plotos "floating, navigable;" Armenian luanam "I wash;" Old English flowan "to flow;" Old Church Slavonic plovo "to flow, navigate;" Lithuanian pilu, pilti "to pour out," plauju, plauti "to swim, rinse").