Gradual recession of water in a sea, lake, or stream, leaving permanently dry land.
reliction - Legal Definition
A gradual shifting of a river’s course, causing it to withdraw from its banks and/or to lower its level. The newly created dry land, if the retreat is permanent, becomes the property of the owner of the adjoining property; the changing of a property’s boundary line by the erosion of land by a river or stream. See also accretion, avulsion, and dereliction.