Abstract
Coastal urbanisation is a widespread phenomenon throughout the world and is often linked to increased erosion. Small Pacific islands are not spared from this issue, which is of great importance in the context of climate change. The French Polynesian island of Bora Bora was used as a case study to investigate the historical evolution of its coastline classification and position from 1955 to 2019. A time series of very high-resolution aerial imagery was processed to highlight the changes of the island’s coastline. The overall length of natural shores, including beaches, decreased by 46% from 1955 to 2019 while human-made shores such as seawalls increased by 476%, and as of 2019 represented 61% of the coastline. This evolution alters sedimentary processes: the time series of aerial images highlights increased erosion in the vicinity of seawalls and embankments, leading to the incremental need to construct additional walls. In addition, the gradual removal of natural shoreline types modifies landscapes and may negatively impact marine biodiversity. Through documenting coastal changes to Bora Bora over time, this study highlights the impacts of human-made structures on erosional processes and underscores the need for sustainable coastal management plans in French Polynesia.
Highlights
This article is an open access articleSince the end of the 19th century, coastal areas have become increasingly sought-after worldwide, and are largely urbanised [1]
Bora Bora (16◦ 290 S, 151◦ 440 W, highest summit: 727 m) is a ~20 km2 tropical volcanic island circled by a 70 km2 barrier reef, in the Society archipelago of French Polynesia in the South Pacific (Figure 1)
High-resolution aerial images of Bora Bora obtained from 1955 to 2019 highlighted the extensive coastal urbanisation undergone by the island since the mid-20th century
Summary
This article is an open access articleSince the end of the 19th century, coastal areas have become increasingly sought-after worldwide, and are largely urbanised [1]. With numerous urban centres and cities located along the shore Infrastructures such as harbours, marinas, and seaside roads have been developed to support local development as well as global maritime trade and transport. In French Polynesia, coastlines have been strongly modified for a range of reasons, mostly since the mid-1900s, from acquiring more land through infilling shallow reef areas to building walls to protect constructions from waves [3,4,5,6]. Along with the dredging of fringing reefs to open navigation channels, sea level rise, and background sediment transport, these modifications lead to changes in shoreline position [7]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
