What does aggradation mean?
Aggradation is the geological process of building up land by depositing material, most often sediment carried and deposited by rivers. As a river channel receives more sediment than it transports away, its bed may rise above the surrounding floodplain, prompting the river to seek a new course and altering drainage patterns, flood risk, and nearby settlements. The word can also describe the growth of a glacier through snowfall. Aggradation is therefore more specific than the broad term deposition: it emphasizes the net accumulation that raises or enlarges a surface. In environmental science, the process matters because gradual aggradation can bury soils, infrastructure, and archaeological remains, while also creating new wetlands and fertile alluvial plains. Although commonly discussed in technical research, the word is readily understood wherever sediment, rivers, and changing landscapes are described. Its contrasting process is degradation, in which material is removed and a surface is lowered or worn down.
nounThe geological process by which land or a landform is built up through the deposition of material, especially sediment. In glaciology, the term also denotes the growth of a glacier through snowfall.
- The buildup of land or a landform through the deposition of material, especially sediment.
- The growth of a glacier through snowfall.
"Over centuries, aggradation raised the riverbed and gradually buried the old floodplain."
"Aggradation buried the old road beneath several metres of river sediment."
"Seasonal snowfall contributed to the gradual aggradation of the alpine glacier."
The plural is appropriate for distinct episodes or bodies of deposited material; the uncountable form is normally used when discussing the process in general.
"The sediments record successive aggradations of the river channel."
A river can bury itself in its own sediment, raising its bed high enough to reshape the surrounding landscape.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Words that share this root
Related word forms
How aggradation is actually used
This is primarily a technical term in geology, geomorphology, and glaciology. It may be used as an uncountable noun for the general process or as a countable noun for a distinct episode or body of deposited material.
Easily confused with aggradation
Aggradation builds material or landform surfaces upward through deposition, whereas degradation lowers or wears them down.