Forecasting Shoreline Changes of Lagoa dos Patos Lagoon, Brazil

• Published in: Journal of coastal research 2003-04, p.43-50
• Main Authors: Toldo, Elírio E., Almeida, Luiz E. S. B., Corrêa, Iran C. S.
• Format: Article
• Language: English
• Subjects: Beaches; Coasts; Lagoons; Littoral transport; Sandspits; Sediment transport; Sediments; Shorelines; Wave energy; Waves
• ISSN: 0749-0208; 1551-5036

The area of Lagoa dos Patos is approximately 10.000 km2, and the basin floor has a mean water depth of about 6 m. The lagoon coastline is essentially composed of unconsolidated Quaternary sediments formed by extensive and continuous sandy beach and sandy spits. Emphasis of the present investigation is to forecasting the processes that control morphodynamic of the shoreline around the lagoon. This paper provides measurements of winds and waves prediction along the coastlines based on one year of wind speed and direction available every 1-hour for all 1988. The statistics of wave parameters used here is described by U.S. ARMY CORPS OF ENGINEERS (1984), prediction model. The lagoonal shoreface is an energetic environment in the Lagoa dos Patos, with the annual mean wave-power incident on the coastlines ranging between 2,057 kW.m-1 about the west margin and 1,046 kW.m-1 about the east margin. The results show that east side of the lagoon received least energy that opposite side, though the storm condition is typical over the east side. Beach system dynamics and corresponding cross-shore sediment transport appear to be primarily controlled by the sediment size. The results of the potential sediment transport along of the east side indicated that sediments are eroded and transported seaward and along of the west side the sediments are generally moved onshore. The longshore currents, to both sides of the lagoon is in agreement to the dominant wind direction, with the littoral drift to dominant north direction on the east side, and to dominant south direction on the west side.