CHANGES IN MORPHOLOGY IN PLANT A COVE BEACH AFTER RIGID STRUCTURES INSTALLATION : THE ITAIPAVA CASE OF ESPIRITO SANTO

Embayed beaches commonly exhibit equilibrium plan shape configurations when the frequent incident waves are controlled by the diffraction process around the headlands that limit them. The equilibrium breaks when the diffraction point changes, which can happen with the presence of hard structures in the influenced area. This article describes the case study on Itaipava beach located in the Itapemirim district, Espirito Santo, Brazil, where a breakwater was built, related to the city harbor extension, took place. The study aimed to reconstruct the morphological evolution of the beach and to discuss the morphodynamic effects of the implementation of this breakwater. The aerial images overlaying allowed to determine the evolution of the coastline over the last 4 decades (1970-2013). The application of parabolic shape model, based on Hsu and Evans (1989), along with the wave data and beach profiles survey were used for the analysis of changes over the affected coastal segment. The study concluded that after the construction of the structures significant changes occurred in plant beach. The results indicated that the northern part of the beach was in static equilibrium before intervention, however, it is now moving to the condition of dynamic equilibrium caused by the intensification of longitudinal drift that removes and transports the sediments from the central portion of the beach towards the harbor. Therefore, both the erosion of the central portion and sedimentation in the protected portion of the beach affected negatively the economic activities of the region such as tourism and fishing. The southern sector has maintained its trend towards progradation. The application of the parabolic shape model together with the analysis of the morphodynamic data allowed the simulation of the adaptive process happened and could have been used before the construction of breakwater in order to predict its consequences.