The Collaborative International Dictionary of English v.0.48:

Diluvial \Di*lu"vi*al\, a. [L. diluvialis. fr. diluvium.]
   1. Of or pertaining to a flood or deluge, esp. to the great
      deluge in the days of Noah; diluvian.
      [1913 Webster]

   2. (Geol.) Effected or produced by a flood or deluge of
      water; -- said of coarse and imperfectly stratified
      deposits along ancient or existing water courses. Similar
      unstratified deposits were formed by the agency of ice.
      The time of deposition has been called the Diluvian epoch.
      [1913 Webster]

WordNet (r) 3.0 (2006):

diluvial
    adj 1: of or connected with a deluge [syn: diluvian,
           diluvial]