A bar-built estuary is an estuary that is formed behind a barrier such as a sandbar or spit, typically found along coastal plains. These estuaries are characterized by their shallow waters and limited tidal exchange with the open ocean. They are important ecosystems and are studied for their unique hydrology and role in coastal sediment dynamics.
Reference: Day, J. W., Kemp, G. P., & Yáñez-Arancibia, A. (2012). Estuarine Ecology. Wiley-Blackwell.