Claudio Neves

Multitemporal Analysis of Coastal Erosion Based on Multisource Satellite Images, Ponta Negra Beach, Natal City, Northeastern Brazil

This paper describes the use of moderate and high-resolution remote sensing images integrated with a Geographic Information System to evaluate the sedimentary balance and morphological changes seen on the sandy beach of Ponta Negra in northeastern Brazil. High-energy forces such as wind, tides, waves, and currents cause widespread erosion and morphodynamic instability along the shoreline. This investigation uses diverse images from multitemporal and multiresolution analyses and a Post-Processing Kinematic Global Positioning System (PPK GPS) survey as the primary resources to study the short and long-term effects of shoreline changes and the processes controlling the persistent horizontal and vertical erosion on the beach. We used moderate-resolution remote sensing images from 1973 to 2012 and high-resolution images from 2003 to 2011. Between 1973 and 2012 a total area of 121,494.52 m2 was affected by erosion and 37,266.58 m2 was affected by accretion. Shoreline progradation rates of 4.2 m/year and recession rates of -3.7 m/year were estimated for the period between 1973 and 1986 and mean erosion rates of 1.5 m/year were estimated from 1986 to 2012. Digital Elevation Model (DEM) comparison resulting from different PPK GPS surveys showed a negative sediment balance of approximately -3,261.94 m3 in a plot of 12,500 m2 between May and September 2012. The coast has also been facing a drastically increased human influence in recent decades. In summary, this article aims to contribute information to support the mitigation of coastal erosion and to protect seaside infrastructure.

Ponta Negra Beach, Natal, Brazil: A Roll and Rock Story

ABSTRACT Scudelari, A.C.; Neves, C.F.; Amaro, V.E., and Santos, O.F., 2016. Ponta Negra Beach, Natal, RN, Brazil: A roll and rock story. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 815–819. Coconut Creek (Florida), ISSN 0749-0208. The paper presents a case study of the erosion process at Ponta Negra Beach, important touristic destination located 15 km south of the downtown area of the city of Natal, capital of the State of Rio Grande do Norte, Northeast Region of Brazil. Unplanned urbanization was followed by an attempt in late 1990s to improve the use of the beach front area. A 4 km long walkway was built along the beach on top of the foredunes, water supply and sewage pipes were buried into the landfill, and a seawall was built to contain the landfill. A slow unattended erosion process was initiated, until in 2012 the seawall and the walkway were severely damaged by waves. Possible causes are discussed and the adopted remedial solutions are presented. The paper should be viewed as a critical reflection on the role of coastal zone management in order to promote sustainable development, based on a tripod: continuous environment monitoring, engineering, and society engagement.

Estudo sobre Tensões no Fundo Induzidas por Ondas em Viveiros de Camarão

Wind action upon the water surface of ponds in shrimp farms is usually considered beneficial because it enhances water oxygenation. However, the wind generated short period waves are very steep, strongly non linear and, upon reflection by the margins, may be amplified. Depending on the water depth which is associated with the seasons when the shrimps are raised or harvested, wave induced bottom stresses may resuspend sediments, cause stress on the animals, and sometimes lead to losses in production. Using wave forecasting formulas for fetch limited regions, wave heights and periods are estimated, bottom stresses are computed for 3 conditions of water depths found in typical shrimp ponds in NE Brazil. The influence of pond length (wind fetch) on wave formation is also verified. Key-words: shrimp farming; sediment transport; waves in ponds; coastal zone management.