Behavior and identification of ephemeral sand dunes at the backshore zone using video images.
The backshore zone is transitional environment strongly affected by ocean, air and sand movements. On dissipative beaches, the formation of ephemeral dunes over the backshore zone plays significant contribution in the beach morphodynamics and sediment budget. The aim of this work is to describe a novel method to identify ephemeral dunes in the backshore region and to discuss their morphodynamic behavior. The beach morphology is identified using Argus video imagery, which reveals the behavior of morphologies at Cassino Beach, Rio Grande do Sul, Brasil. Daily images from 2005 to 2007, topographic profiles, meteorological data, and sedimentological parameters were used to determine the frequency and pervasiveness of these features on the backshore. Results indicated that coastline orientation relative to the dominant NE and E winds and the dissipative morphological beach state favored aeolian sand transport towards the backshore. Prevailing NE winds increase sand transportation to the backshore, resulting in the formation of barchans, transverse, and barchanoid-linguiod dunes. Precipitation inhibits aeolian transport and ephemeral dune formation and maintains the existing morphologies during strong SE and SW winds, provided the storm surge is not too high.
Laboratório de Oceanografia Geológica, Instituto de Oceanografia, Universidade Federal do Rio Grande, Av. Itália, Km 8, Caixa Postal 474, 96201-900 Rio Grande, RS, Brasil.
Pedro V
PV
Guimarães
Laboratório de Oceanografia Geológica, Departamento de Oceanografia, Universidade Federal de Pernambuco, Av. Arquitetura, s/n, Cidade Universitária, 50740-550 Recife, PE, Brasil.
Pedro S
PS
Pereira
Laboratório de Oceanografia Geológica, Instituto de Oceanografia, Universidade Federal do Rio Grande, Av. Itália, Km 8, Caixa Postal 474, 96201-900 Rio Grande, RS, Brasil.
Lauro J
LJ
Calliari
Department of Geography and Marine Science Program, University of South Carolina, Columbia, SC, 29208, USA.
Jean T
JT
Ellis