Study of the Ponta Negra Beach Surface in Manaus / AM: Evidence and Causes of Mass Movement of the Artificial Beach Landfill

Abstract

Ponta Negra Beach is located on the banks of the Rio Negro, in the city of Manaus, state of Amazonas, Brazil. In 2012, a revitalization of the beach was carried out, with emphasis on the construction of an artificial beach landfill, in order to perpetuate the population's access to the beach throughout the hydrological year. This work resulted in the formation of several irregularities throughout the terrain, such as cavities, plumbing and pipes exposed on the surface, and sudden cavities between shallower and deeper parts of the bed. These problems have resulted in several fatalities since the opening of the landfill. Given these questions, this study aimed to assess the changes that occur on the beach surface, through analysis of sediments, topography and space, as a result of the construction work, for a period of two to three years, and thus, to identify the cause of these problems to understand what failures occurred in the construction of the landfill that led to the formation of these irregularities. The results showed that the grounded sediments from the artificial beach are being transported more easily by the force of the river and the rains because they are finer sediments than those of the natural beach, intensifying the erosion rates and resulting in the generation of ravines and depressions along the entire beach, being responsible for the movement of sandy mass of the ladfill and in the formation of the irregularities found. This study proves that the anthropic relationships interfered in the natural processes that act on the beach's morphology, warning the importance of serious previous studies in the execution of works with landfills and their continuous maintenance