Morphodynamic study of sandy beaches in a tropical tidal inlet using RPAS

Abstract This study analyzed the seasonal variation of sedimentary reservoirs in sandy beaches located at the insular margin of a tidal inlet (Itamaraca Island, Pernambuco, Brazil). We measured the sedimentary budget and identified the dominant coastal processes (accretion or erosion) from Dec/2017 to Dec/2018. In six field campaigns by a Remotely Piloted Aircraft System, digital terrain models and extracted cross shore profiles were obtained which allowed for the quantification of beach morphology variability by variations in sedimentary volume. The following three sectors were classified and analyzed according to their location and coastal alignment in relation to the tidal inlet: internal (O–L), intermediate (SW–NE), and external (S N) sectors. ERA Interim reanalysis data were used to evaluate the regional standards of ocean surface waves and wind, showing predominance of southeast (109° and 124°, respectively) and wave power with average peaks of 46.5–51.8 kW/m (dry season) and 57–65.3 kW/m (rainy season). Sedimentary gain took place between Apr–Jul/2018, with Sep–Dec/2018 being the period of greatest loss. The internal sector showed positive sedimentary budget (+704.52 m3) with the prevalence of the accretion process, while both intermediate and external sectors lost about 5009 and 14,110 m3, respectively, with the erosive process prevailing at the end of the studied period.