Gabions for the protection of Caponga Beach, Ceará Brazil: hazards and management

Abstract

This paper attempts to the hazards assessment and how to manage the hydrodynamic sedimentary processes stemmed from the emplacement of a set of gabions located at the stretch of a beach in Cascavel municipality, Ceará State, Northeast Brazil. The present littoral morphodynamics related to the wave climate, swash and backwash processes and anthropic activities actually held in the area, has been also considered. Top-hydrographic profiles, sediment sampling, and textural analysis all over the year of 2001 have been performed. The results were compared to the previous ones aiming at achieving the state of the art of the coastal hydrodynamics processes and their relationship to the degeneration and/or regeneration of the coastline morphology together with its uses and occupation. The beach zonation have been worked out, different compartments and three cells were calculated which allowed the definition of vulnerability inside in each one of the sectors. The progradation and inverse beach shift have been assigned to be cyclic process, but it must be said that wave refraction and diffraction, offroad vehicles and vandalism on the rigid structures and the dwelling of sediment supplying areas are responsible for part of the process during 2001. At the same time the Caponga Roseira flooding runoff responds for most of these processes at cell 3. This has been also compared to the development carried out in 2003. This lead to prevent future inadequate occupation of backshore that is nowadays taking place.