Definition: A tract of alluvium formed at the mouth of a river where the deposition ofsome of its load exceeds its rate of removal, crossed by the divergent channels (distributaries) of the river.
Definition: A habitat that is in or on a body of water containing low concentrations of dissolved salts and other total dissolved solids (<0.5 grams dissolved salts per litre).
Comment: "Small" is ambiguous. For details on "Small rivers" (e.g. the Salween river) see http://worldwildlife.org/biomes/small-river-ecosystems. This class will be replaced with a less ambiguous class.