Wave prediction along Lagoa dos Patos coastline, southern Brazil

Abstract

Information on winds and waves near the coast is critical to scientists and coastal engineers working with coastal structure design, erosion rate estimates, navigation safety, and recreational purposes. This paper presents the first wind measurements and wave predictions along the coastline of Lagoa dos Patos based on one year’s wind velocity and direction data recorded every hour during 1988. Due to the prevailing northeastern wind during the summer and spring, the dominant wave direction on the west margin of the lagoon is NE and ENE, with significant wave height between 0.5-0.7 m and periods between 2.7-3.3 s. On the east side, during winter and autumn, WNW and WSW winds cause a maximum wave height of 1.6 m and period of 4.8 s, and significant wave heights between 0.4-0.8 m and periods between 2.4-3.4 s, respectively. The high frequency and short duration of winds with velocity between 0-2 m/s is the main factor controlling wave height in the lagoon. The average 6-m depth in this shallow and elongated lagoon acts as a secondary factor reducing wave height.