Special Issue "Drones for Coastal Environments"

A special issue of Drones (ISSN 2504-446X).

Deadline for manuscript submissions: closed (8 March 2019).

Special Issue Editors

Dr. Javier Leon
E-Mail Website
Guest Editor
School of Science and Engineering, University of the Sunshine Coast, 90 Sippy Downs Drive, Sippy Downs, QLD 4558, Australia
Interests: coastal geography; geomorphology; GIS; remote sensing; drones; terrain analysis; object-based image analysis
Dr. Daniel Harris
E-Mail Website
Guest Editor
School of Earth and Environmental Sciences, The University of Queensland, Brisbane, QLD, 4072, Australia
Interests: coastal morphodynamics; coral reefs; coastal geomorphology
Dr. Karen Joyce
E-Mail Website
Guest Editor
Senior Lecturer - Remote Sensing and Spatial Sciences, College of Science and Engineering, James Cook University, Cairns, QLD, 4870 Australia
Tel. +61 7 4232 1429
Interests: remote sensing; coral reefs; unmanned airborne systems
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

Coastal environments and the ecosystem services they provide are of vital importance to societies as 1.9 billion people globally live within 100 km of the land and ocean interface. For example, sandy beaches, which comprise 75% of the world’s ice-free coastline, are prime sites for development, recreation, tourism, housing, and fisheries. Coral reefs only cover less than 1% of the Earth’s surface, yet they support at least 500 million people providing food, coastal protection, and livelihoods, globally valued at an estimated U$9.9 trillion.

Coastal systems are also highly dynamic environments and very susceptible to the ongoing impacts of climate change. Mapping and monitoring their trajectories and recoveries from impacts is essential to better understand and manage them. However, biophysical datasets at appropriate spatial and temporal scales are seldom available due to the inherent challenges of working in coastal settings.  

Drones are allowing the acquisition of very-high spatial resolution spatial data (pixel sizes in the order of centimetres) across relatively large areas with great flexibility in the timing and frequency of image capture. This effectively bridges the gap between detailed field data collection and synoptic remotely-sensed data and offers an unprecedented opportunity to study and monitor coastal environments.

This Special Issue of Drones seeks to find the latest research in the application of drone technology to coastal environments including, but not limited to, sandy beaches, coral reefs, mangroves, saltmarshes, seagrass or rocky coastlines. We invite contributions that address one or more of the following topics:

  • Semi-automatic change detection approaches
  • Challenges associated with mapping the land-ocean interface
  • Accuracy of derived data
  • Cost-effectiveness assessments
  • Novel platform/sensors for coastal applications
Dr. Javier Leon
Dr. Daniel Harris
Dr. Karen Joyce
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Drones is an international peer-reviewed open access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (7 papers)

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Research

Open AccessArticle
Assessing Reef-Island Shoreline Change Using UAV-Derived Orthomosaics and Digital Surface Models
Drones 2019, 3(2), 44; https://doi.org/10.3390/drones3020044 - 14 May 2019
Abstract
This study presents an analysis of shoreline change on reef islands using unmanned aerial vehicle (UAV)-derived orthomosaics and digital surface models (DSMs) collected on Sipadan Island, Sabah, Malaysia, and Sasahura Ite Island, Isabel Province, Solomon Islands. The high resolution of UAV-derived orthomosaics enabled [...] Read more.
This study presents an analysis of shoreline change on reef islands using unmanned aerial vehicle (UAV)-derived orthomosaics and digital surface models (DSMs) collected on Sipadan Island, Sabah, Malaysia, and Sasahura Ite Island, Isabel Province, Solomon Islands. The high resolution of UAV-derived orthomosaics enabled changes in the position of the base of beach to be detected with confidence. The accuracy of the UAV-derived DSMs was assessed against equivalent topographic profiles via root-mean-square error, and found to be <0.21 m in all but one case; this demonstrates the potential for using UAV-derived DSMs to interpret three-dimensional island beach morphology and detect patterns of geomorphic change. The correlation between planimetric and volumetric change along selected beach transects was also investigated and found to be variable, indicating that a multifaceted approach including both planimetric (two-dimensional) and volumetric (three-dimensional) metrics is of value when analysing reef-island change. However, interpretations of UAV-derived data must carefully consider errors associated with global positioning system (GPS) positioning, the distribution of ground control points, the chosen UAV flight parameters, and the data processing methodology. Further application of this technology has the potential to expand our understanding of reef-island morphodynamics and their vulnerability to sea-level rise and other stressors. Full article
(This article belongs to the Special Issue Drones for Coastal Environments)
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Open AccessArticle
Morphological Exposure of Rocky Platforms: Filling the Hazard Gap Using UAVs
Drones 2019, 3(2), 42; https://doi.org/10.3390/drones3020042 - 03 May 2019
Abstract
Rock platforms are dangerous environments commonly subject to high wave energy on the open coast. Platform morphology is central to understanding what makes one stretch of coastline more hazardous than another, and it can be used to create site-specific morphological exposure hazard indices [...] Read more.
Rock platforms are dangerous environments commonly subject to high wave energy on the open coast. Platform morphology is central to understanding what makes one stretch of coastline more hazardous than another, and it can be used to create site-specific morphological exposure hazard indices to assess the relative risk of being washed into the sea, assisting coastal managers in an effort to reduce the number of injuries and drowning incidents. This paper describes the use of an unmanned aerial vehicle (UAV) to derive morphological parameters for two data-poor rock platforms along the Illawarra coast of southern New South Wales, to fill the gap using an easily replicable site-specific hazard index, developed previously, that can be applied to other microtidal wave-dominated settings. The approach is based on the subdivision of the terrestrial seaward edge of platforms into segments, classified according to mean elevation, orientation and edge type, to model different weighting scenarios of predominant southeasterly and northeasterly wave direction. UAV-derived results were deemed satisfactory for all study sites, and a comparison of results derived from LiDAR for two platforms suggested that UAV data can be successfully used to guide risk policy on rock coasts, despite differences in the delimitation of the seaward edge due to tidal level during survey acquisition. Full article
(This article belongs to the Special Issue Drones for Coastal Environments)
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Open AccessArticle
Reef Rover: A Low-Cost Small Autonomous Unmanned Surface Vehicle (USV) for Mapping and Monitoring Coral Reefs
Drones 2019, 3(2), 38; https://doi.org/10.3390/drones3020038 - 17 Apr 2019
Abstract
In the effort to design a more repeatable and consistent platform to collect data for Structure from Motion (SfM) monitoring of coral reefs and other benthic habitats, we explore the use of recent advances in open source Global Positioning System (GPS)-guided drone technology [...] Read more.
In the effort to design a more repeatable and consistent platform to collect data for Structure from Motion (SfM) monitoring of coral reefs and other benthic habitats, we explore the use of recent advances in open source Global Positioning System (GPS)-guided drone technology to design and test a low-cost and transportable small unmanned surface vehicle (sUSV). The vehicle operates using Ardupilot open source software and can be used by local scientists and marine managers to map and monitor marine environments in shallow areas (<20 m) with commensurate visibility. The imaging system uses two Sony a6300 mirrorless cameras to collect stereo photos that can be later processed using photogrammetry software to create underwater high-resolution orthophoto mosaics and digital surface models. The propulsion system consists of two small brushless motors powered by lithium batteries that follow pre-programmed survey transects and are operated by a GPS-guided autopilot control board. Results from our project suggest the sUSV provides a repeatable, viable, and low-cost (<$3000 USD) solution for acquiring images of benthic environments on a frequent basis from directly below the water surface. These images can be used to create SfM models that provide very detailed images and measurements that can be used to monitor changes in biodiversity, reef erosion/accretion, and assessing health conditions. Full article
(This article belongs to the Special Issue Drones for Coastal Environments)
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Open AccessArticle
Estimating Mangrove Forest Volume Using Terrestrial Laser Scanning and UAV-Derived Structure-from-Motion
Drones 2019, 3(2), 32; https://doi.org/10.3390/drones3020032 - 01 Apr 2019
Abstract
Mangroves provide a variety of ecosystem services, which can be related to their structural complexity and ability to store carbon in the above ground biomass (AGB). Quantifying AGB in mangroves has traditionally been conducted using destructive, time-consuming, and costly methods, however, Structure-from-Motion Multi-View [...] Read more.
Mangroves provide a variety of ecosystem services, which can be related to their structural complexity and ability to store carbon in the above ground biomass (AGB). Quantifying AGB in mangroves has traditionally been conducted using destructive, time-consuming, and costly methods, however, Structure-from-Motion Multi-View Stereo (SfM-MVS) combined with unmanned aerial vehicle (UAV) imagery may provide an alternative. Here, we compared the ability of SfM-MVS with terrestrial laser scanning (TLS) to capture forest structure and volume in three mangrove sites of differing stand age and species composition. We describe forest structure in terms of point density, while forest volume is estimated as a proxy for AGB using the surface differencing method. In general, SfM-MVS poorly captured mangrove forest structure, but was efficient in capturing the canopy height for volume estimations. The differences in volume estimations between TLS and SfM-MVS were higher in the juvenile age site (42.95%) than the mixed (28.23%) or mature (12.72%) age sites, with a higher stem density affecting point capture in both methods. These results can be used to inform non-destructive, cost-effective, and timely assessments of forest structure or AGB in mangroves in the future. Full article
(This article belongs to the Special Issue Drones for Coastal Environments)
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Open AccessCommunication
A Rapid UAV Method for Assessing Body Condition in Fur Seals
Drones 2019, 3(1), 24; https://doi.org/10.3390/drones3010024 - 06 Mar 2019
Abstract
Condition indices correlating body lipid content with mass and morphometric measurements have been developed for a variety of taxa. However, for many large species, the capture and handling of enough animals to obtain representative population estimates is not logistically feasible. The relatively low [...] Read more.
Condition indices correlating body lipid content with mass and morphometric measurements have been developed for a variety of taxa. However, for many large species, the capture and handling of enough animals to obtain representative population estimates is not logistically feasible. The relatively low cost and reduced disturbance effects of UAVs make them ideal for the rapid acquisition of high volume data for monitoring large species. This study examined the imagery collected from two different UAVs, flown at 25 m altitude, and the subsequent georeferenced orthomosaics as a method for measuring length and axillary girth of Australian fur seals (Arctocephalus pusillus doriferus) to derive an index of body condition. Up to 26% of individuals were orientated correctly (prostrate/sternal recumbent) to allow for body measurements. The UAV-obtained images over-estimated axillary girth diameter due to postural sag on the lateral sides of the thorax while the animals are lying flat in the sternal recumbent position on granite rocks. However, the relationship between axillary girth and standard length was similarly positive for the remotely- and physically-obtained measurements. This indicates that residual values from the remotely-obtained measurements can be used as a relative index of body condition. Full article
(This article belongs to the Special Issue Drones for Coastal Environments)
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Open AccessArticle
Suggestions to Limit Geometric Distortions in the Reconstruction of Linear Coastal Landforms by SfM Photogrammetry with PhotoScan® and MicMac® for UAV Surveys with Restricted GCPs Pattern
Drones 2019, 3(1), 2; https://doi.org/10.3390/drones3010002 - 23 Dec 2018
Cited by 4
Abstract
Owing to the combination of technological progress in Unmanned Aerial Vehicles (UAVs) and recent advances in photogrammetry processing with the development of the Structure-from-Motion (SfM) approach, UAV photogrammetry enables the rapid acquisition of high resolution topographic data at low cost. This method is [...] Read more.
Owing to the combination of technological progress in Unmanned Aerial Vehicles (UAVs) and recent advances in photogrammetry processing with the development of the Structure-from-Motion (SfM) approach, UAV photogrammetry enables the rapid acquisition of high resolution topographic data at low cost. This method is particularly widely used for geomorphological surveys of linear coastal landforms. However, linear surveys are generally pointed out as problematic cases because of geometric distortions creating a “bowl effect” in the computed Digital Elevation Model (DEM). Secondly, the survey of linear coastal landforms is associated with peculiar constraints for Ground Control Points (GCPs) measurements and for the spatial distribution of the tie points. This article aims to assess the extent of the bowl effects affecting the DEM generated above a linear beach with a restricted distribution of GCPs, using different acquisition scenarios and different processing procedures, both with PhotoScan® software tool and MicMac® software tool. It appears that, with a poor distribution of the GCPs, a flight scenario that favors viewing angles diversity can limit DEM’s bowl effect. Moreover, the quality of the resulting DEM also depends on the good match between the flight plan strategy and the software tool via the choice of a relevant camera distortion model. Full article
(This article belongs to the Special Issue Drones for Coastal Environments)
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Open AccessArticle
Drone-Based High-Resolution Tracking of Aquatic Vertebrates
Drones 2018, 2(4), 37; https://doi.org/10.3390/drones2040037 - 08 Nov 2018
Cited by 5
Abstract
Determining the small-scale movement patterns of marine vertebrates usually requires invasive active acoustic tagging or in-water monitoring, with the inherent behavioural impacts of those techniques. In addition, these techniques rarely allow direct continuous behavioural assessments or the recording of environmental interactions, especially for [...] Read more.
Determining the small-scale movement patterns of marine vertebrates usually requires invasive active acoustic tagging or in-water monitoring, with the inherent behavioural impacts of those techniques. In addition, these techniques rarely allow direct continuous behavioural assessments or the recording of environmental interactions, especially for highly mobile species. Here, we trial a novel method of assessing small-scale movement patterns of marine vertebrates using an unmanned aerial vehicle that could complement longer-term tracking approaches. This approach is unlikely to have behavioural impacts and provides high accuracy and high frequency location data (10 Hz), while subsequently allowing quantitative trajectory analysis. Unmanned aerial vehicle tracking is also relatively low cost compared to single-use acoustic and GPS tags. We tracked 14 sharks for up to 10 min in a shallow lagoon of Heron Island, Australia. Trajectory analysis revealed that Epaulette sharks (Hemiscyllium ocellatum) displayed sinusoidal movement patterns, while Blacktip Reef Sharks (Carcharhinus melanopterus) had more linear trajectories that were similar to those of a Lemon shark (Negaprion acutidens). Individual shark trajectory patterns and movement speeds were highly variable. Results indicate that Epaulette sharks may be more mobile during diurnal low tides than previously thought. The approach presented here allows the movements and behaviours of marine vertebrates to be analysed at resolutions not previously possible without complex and expensive acoustic arrays. This method would be useful to assess the habitat use and behaviours of sharks and rays in shallow water environments, where they are most likely to interact with humans. Full article
(This article belongs to the Special Issue Drones for Coastal Environments)
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