Prevision and consequences of a new inlet opening at Mar do Ararapira, southern Brazil

Abstract

Mar do Ararapira is an estuary isolated from the sea by a narrow spit and with an inlet that migrate to the Southwest. There are previsions that the migration could change suddenly by a new inlet opening. This work aims to determine the spit morphological evolution, estimate the inlet migration rate and the new inlet opening date, anticipate the morphological estuarine and coastal changes after the new inlet opening and evaluate the social and political implications of those changes. To achieve these objectives different data aerial photographs were interpreted and topographic profiles at the narrower spit place were performed. One can conclude that a new inlet located 6 km farther northeast will open at 2012 to 2016. The opening will cause the present inlet silting, strong erosion at the coasts near to the present inlet and strong accretion at the coast near to the new one. These changes will affect the three villages around, environmental protected areas administration and states government. The anticipation of the new inlet opening consequences on the local communities and state and environmental protected areas borders will provide preventive actions to minimize the adverse effects of the coastal changes. Monitoring the coastal changes after the inlet opening will allow verifying if the anticipations are correct and help to improve the understanding of future similar events.