Sub-aqueous (underwater) dunes form on a bed of sand or gravel under the actions of water flow. They are ubiquitous in natural channels such as rivers and estuaries, and also form in engineered canals and pipelines. Dunes move downstream as the upstream slope is eroded and the sediment deposited on the downstream or lee slope in typical bedform construction.Prothero, D. R. and Schwab, F., 1996, Sedimentary Geology, pg. 45–49, In the case of sub-aqueous barchan dunes, sediment is lost by their extremities, known as horns.
Sub-aqueous (underwater) dunes form on a bed of sand or gravel under the actions of water flow. They are ubiquitous in natural channels such as rivers and estuaries, and also form in engineered canals and pipelines. Dunes move downstream as the upstream slope is eroded and the sediment deposited on the downstream or lee slope in typical bedform construction.Prothero, D. R. and Schwab, F., 1996, Sedimentary Geology, pg. 45–49, In the case of sub-aqueous barchan dunes, sediment is lost by their extremities, known as horns.