Using direct and indirect methods to assess the influence of high-energy waves over beach sedimentary balance (Brazilian Northeastern Region)

Abstract

Because of the high dynamicity of atmospheric and oceanographic variables in coastal processes, local sedimentary balance is a matter of great interest for Integrated Coastal Zone Management. The diversity of environmental factors associated with the history of anthropic interventions, in addition to detailed topographic changes related to storm surge events, is assessed in this research for a stretch of the northeastern Brazilian coast. For this purpose, an association of conventional and improved digital methods was applied for data acquisition and processing. Remote sensing techniques with unmanned aerial vehicles (UAVs), three-dimensional modeling, and sedimentary analysis were performed, as well as detailed monitoring of meteorological and oceanographic variables with in situ sources and environmental modeling. The results of 1-year monitoring revealed a sedimentary balance with different variations in response to high-energy events associated with extratropical cyclones in the North Atlantic. The sedimentary balance showed an erosional rate of 25.5%, reflected in a 17.4% diminution in average topographic level of the area. Beach erosion was correlated to long period waves and great variability of wave types. Positive volumetric changes were correlated to mild weather environmental conditions. Swell waves presented a significant role in both beach erosion and following consequential topographic recovery. There was an asymmetric susceptibility to volume losses in different beach sectors.