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

Abstract

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.