fluvial

from WordNet (r) 3.0 (2006)

fluvial
    adj 1: of or relating to or happening in a river; "fluvial
           deposits"

from The Collaborative International Dictionary of English v.0.48

Fluvial \Flu"vi*al\, a. [L. fluvialis, from fluvius river, fr.
   fluere to flow: cf.F. fluvial. See {Fluent}.]
   Belonging to rivers; growing or living in streams or ponds;
   as, a fluvial plant.
   [1913 Webster]