aggradation
noun
ag·gra·da·tion ˌa-grə-ˈdā-shən 
: a modification of the earth's surface in the direction of uniformity of grade by deposition
aggradational
ˌa-grə-ˈdā-shnəl
adjective -shə-nᵊl
Example Sentences
Recent Examples on the Web Number one is aggradation of the channel bed, and number two, a mega flood. 
Mark Schleifstein, NOLA.com, 12 Dec. 2017
Mark Schleifstein, NOLA.com, 12 Dec. 2017 Word History
Etymology
aggrade "to fill with detrital material, build up by aggradation" (from ad- + -grade, as in degrade) + -ation (after degradation)
Note: Aggrade and aggradation were apparently introduced by the geologist Rollin D. Salisbury in Surface Geology: Report of Progress, from the Annual Report of the State Geologist for 1892, Trenton, N.J.: Geological Survey of New Jersey, 1893, p. 103.
First Known Use
1898, in the meaning defined above