Kment, (E) trees. (E) trees.two.1.2. Human Presence Bora Bora’s initially infrastructures were constructed for the duration of the 1940s, with an airport, roads, quays, embankments. Considering the fact that then, Bora Bora has been the stage of a crucial demographic boom (2215 inhabitants in 1971, ten,549 in 2017 [14]; average population density in 2017: 350/km2 ) and financial improvement, most notably through tourism and recreational activities (more than 80 of international tourists coming to French Polynesia go to the island [15]). This demographic and economic development is connected with all the rapid urbanisation of the coastline, as most of the inner island is constituted of steep cliffs and dense forest. Faanui and Vaitape (Figure two), on the western side, property more than two thirds of your island’s population while Anau within the east features a population of around 2000. This urbanisation is accompanied by coastal modifications (dredging and removal of sand to make roads, authorised and unauthorised land fillings to extend gardens and homes more than the fringing reef) and structures (roads, quays, embankments, seawalls). two.two. Information Acquisition The study is depending on a time series of pictures of Bora Bora obtained through vertical aerial photographs taken from a plane, offered by the Urbanism service of French Polynesia (1955, 1977, 1987, and 1999) and satellite imagery extracted from Google Earth (2006, 2010, 2019), as detailed in Table 1. These dates had been chosen for their negligible or absent cloud cover. The satellite imagery was extracted at pretty higher spatial resolution (0.five m) from Google Earth following the technique from [16]; by adjusting the eye altitude to match the satellite spatial resolution, placing the nadir at 90 , and positioning the view northward, over 60 images of your island have been saved at maximum resolution for each date, with an overlap of about 30 amongst each subsequent image; these images have been then assembled into orthomosaics similarly for the aerial photos taken from a plane (see Section 2.three.1. Image preparation). Moreover, a ground-based survey on the coastalRemote Sens. 2021, 13,six oftypology was performed in 2019 employing a GPS, by walking and sailing about the island and Mirogabalin besylate medchemexpress recording the place of diverse coastal types (related methodology to [3]).Table 1. Year, variety of image, and spatial resolution with the time series of images of Bora Bora. Year 1955 1977 1987 1999 2006 2010 2019 Acquisition Method Plane Plane Plane Plane Satellite Satellite Satellite Supply Aerial photographs Aerial photographs Aerial photographs Aerial photographs Maxar Technologies Maxar Technologies CNES/Airbus Image Form Singleband grey Singleband grey Singleband grey 2-Methoxyestradiol manufacturer Multiband colour Multiband colour Multiband colour Multiband colour Spatial Resolution (m) 1.58 0.64 0.52 0.41 0.48 0.50 0.2.three. Data Processing two.three.1. Image Preparation The images had been assembled making use of Agisoft Metashape to get orthomosaics for every single acquisition year. These have been georeferenced with ArcGIS 10.eight.1 applying ground control points (geospatial reference: tefenua.gov.pf (accessed on 15 January 2021)) with either adjust or 2nd polynomial transformations. Fixed geomorphological capabilities for example lagoon pinnacles had been made use of along with anthropogenic attributes as ground control points (similarly to [17]). 2.three.two. Shoreline Tracing The shoreline was manually traced determined by the sea-side edge of vegetation (which includes the sea-side edge of mangroves and grass/reed regions), as per preceding publications (similarly to the stabil.