Sediment-deficit sink-zone morphodynamics in oceanic island dune systems: integration of field data and remote sources in the Macaronesian Region

Abstract

Highlights What are the main findings? The sink area of dune systems on oceanic islands, such as those in Macaronesia, reflects the sediment deficit inherited from actions carried out throughout the systems. The integration of field data and remote sources has facilitated the identification of erosional trends across diverse spatiotemporal scales. What are the implications of the main findings? Management and protection measures aimed at addressing sediment deficits in sink areas of dune systems must consider the entire system to ensure the efficacy of the approach. The methodology can be replicated for the identification of erosional trends in sink areas of other oceanic island dune systems.Highlights What are the main findings? The sink area of dune systems on oceanic islands, such as those in Macaronesia, reflects the sediment deficit inherited from actions carried out throughout the systems. The integration of field data and remote sources has facilitated the identification of erosional trends across diverse spatiotemporal scales. What are the implications of the main findings? Management and protection measures aimed at addressing sediment deficits in sink areas of dune systems must consider the entire system to ensure the efficacy of the approach. The methodology can be replicated for the identification of erosional trends in sink areas of other oceanic island dune systems. Coastal erosion has become a significant problem in the context of global warming and sea level rise. The combination of these factors which, in some cases, produces sedimentary deficit, is causing flooding problems that affect coastal ecosystems such as dune systems. This problem is of particular concern in the context of oceanic islands, where sandy coasts and dune systems are considered to be of significant value. As terminal areas of encapsulated sedimentary systems, sink areas are subject to the downwind effects of current and historical management and uses developed throughout the entire system. The objective of this research is to analyze the evolution of the Sink Zones (they mainly demonstrate behaviors akin to those exhibited by beaches), in various dune systems in Macaronesia, with a particular focus on the Canary Islands (Maspalomas in Gran Canaria, Jand & iacute;a in Fuerteventura and La Graciosa Island) and Cabo Verde (Costa Fragata-Ponta Preta in Sal Island). A multiscale spatio-temporal approach was employed, utilizing historical and contemporary orthophotos and topographic data (obtained from LiDAR flights with airplanes and photogrammetric flights with drones) to analyze the evolution of the coastline using DSAS software (version 6.0). In the specific instance of the island of La Graciosa, these data were integrated with detailed fieldwork data on wind conditions and sediment characterization. This methodology was utilized to ascertain the morphodynamical response of the aforementioned Sink Zones. The results obtained from the analyses reveal the presence of erosion processes, thus prompting a comprehensive discussion concerning the management and utilization of these natural systems, in addition to the potential impact of climate change.