Alluvion is a legal term which describes the increase in the area of land due to accumulation of soil, clay or other material deposited by water. The added land belongs to the owner of the property to which it is added. This changes the size of a piece of land (a process called accession) and thus its value over time. It is also termed as alluvium.
In Louisiana, accretion formed successively and imperceptibly on the bank of a river or stream, whether navigable or not, is called alluvion. Even though the alluvion belongs to the owner of the bank, s/he is bound to leave public that portion of the bank which is required for the public use. The same rule applies to dereliction formed by water receding imperceptibly from a bank of a river or stream. The owner of the land situated at the edge of the bank left dry owns the dereliction. [La. C.C. Art. 499]
Alluvion formed in front of the property of several owners is divided equitably, taking into account the extent of the front of each property prior to the formation of the alluvion in issue. Each owner is entitled to a fair proportion of the area of the alluvion and a fair proportion of the new frontage on the river, depending on the relative values of the frontage and the acreage.[ La. C.C. Art. 501]
Alluvion, in Roman and Civil law refers to the flow or wash of water against a shore or riverbank. The word is derived from the Latin word alluvio which means “flood.”