Abstract
Coastal dunes are globally-distributed dynamic ecosystems that occur at the land-sea interface. They are sensitive to disturbance both from natural forces and anthropogenic stressors, and therefore require regular monitoring to track changes in their form and function ultimately informing management decisions. Existing techniques employing satellite or airborne data lack the temporal or spatial resolution to resolve fine-scale changes in these environments, both temporally and spatially whilst fine-scale in-situ monitoring (e.g., terrestrial laser scanning) can be costly and is therefore confined to relatively small areas. The rise of proximal sensing-based Structure-from-Motion Multi-View Stereo (SfM-MVS) photogrammetric techniques for land surface surveying offers an alternative, scale-appropriate method for spatially distributed surveying of dune systems. Here we present the results of an inter- and intra-annual experiment which utilised a low-cost and highly portable kite aerial photography (KAP) and SfM-MVS workflow to track sub-decimetre spatial scale changes in dune morphology over timescales of between 3 and 12 months. We also compare KAP and drone surveys undertaken at near-coincident times of the same dune system to test the KAP reproducibility. Using a Monte Carlo based change detection approach (Multiscale Model to Model Cloud Comparison (M3C2)) which quantifies and accounts for survey uncertainty, we show that the KAP-based survey technique, whilst exhibiting higher x, y, z uncertainties than the equivalent drone methodology, is capable of delivering data describing dune system topographical change. Significant change (according to M3C2); both positive (accretion) and negative (erosion) was detected across 3, 6 and 12 months timescales with the majority of change detected below 500 mm. Significant topographic changes as small as ~20 mm were detected between surveys. We demonstrate that portable, low-cost consumer-grade KAP survey techniques, which have been employed for decades for hobbyist aerial photography, can now deliver science-grade data, and we argue that kites are well-suited to coastal survey where winds and sediment might otherwise impede surveys by other proximal sensing platforms, such as drones.
Highlights
Sand dune ecosystems are globally distributed [1], covering approximately 34% of the world’s ice-free coastlines [2], and they form on many types of shores and under a variety of climatic conditions [3]
We address the following research questions to explore these knowledge gaps: (1) How do data from a kite aerial photography (KAP) system processed with Structure-from-Motion Multi-View Stereo (SfM-MVS) methodology compare to similar data captured from a more stable drone system for sand-dune morphological assessment at a single point in time? Given existing work that allows robust estimates of spatial uncertainty to be obtained for SfM-MVS derived point clouds (e.g., M3C2-Precision Mapping (M3C2-PM)), we apply such methods to the data produced from the drone survey and a single KAP survey to understand differences in the data produced
Using an SfM-MVS workflow (Figure 3), point cloud, DEM and orthomosaic products (Figures S3 and S4) were produced for each of the six KAP surveys and one drone survey undertaken at the study site (Table 1)
Summary
Sand dune ecosystems are globally distributed [1], covering approximately 34% of the world’s ice-free coastlines [2], and they form on many types of shores and under a variety of climatic conditions [3]. They deliver critical ecosystem services such as coastal protection [4] as well as providing environmental heterogeneity which promotes ecological diversity [5]. Other services include nutrient cycling, well-being and recreation, and mineral extraction [6] Whilst these services are beneficial to human populations at the coast and beyond, coastal sand dune environments face pressures. There is a pressing need to monitor these sensitive environments in order to inform management decisions for preserving their integrity and averting irreversible damage [10]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
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.
