Erosive processes monitoring linked to the estuarine evolution systems nearby Aguas Belas, Cascavel,Ceará, Brazil

Abstract

The Malcozinhado estuarine-lagoon system, at NE-Brazil, is located at the County of Cascavel, 75 km to southeastof the city of Fortaleza-CE. Its drainage basin occupies an area of 380 km that due to its high aesthetic value, was included in the PRODETURIS Rota do Sol Nascente (Sun Rise Route) a Touristic Project. The urban expansion that took place during the last two decades resulted in a series of impact upon the Malcozinhado estuary and upon adjacent beaches, such as beach erosion, hypersalinization and outlet migration over urban areas. This problem is expected get worse as a 3,800,000 m reservoir for water supply is being built, 7.5 km upstream and will further reduce the Malcozinhado river flow, thus its capacity to maintain its original channel and impair saltwater intrusion. We aimed to assess and monitor the evolution of estuarine and beach morphodynamic and hydrodynamic behavior nearby the Águas Belas village in the search for information that can contribute to solve and/or mitigate present environmental conflicts. Available aerial photographs, images and maps for the area were analyzed, CTD profiles and current measurements taken at ten stations along the Malcozinhado estuary, for a full tidal cycle, during dry and rainy seasons, in addition to conduction of bathymetric survey of the estuary cross-section. The system dynamic is highly dependent of the freshwater discharge that together with the sediment reworking processes, longshore drift, eolian deflation and tides composes a cyclical framework well marked by wet and dry semi-arid conditions typical of tropical regions.