UAS &amp; S<i>f</i>M-based approach to Monitor Overwash Dynamics and Beach Evolution in a Sandy Spit

Talavera, Lara; Río, Laura Del; Benavente, Javier; Barbero, L.; Ramírez, Juan Antonio López

doi:10.2112/si85-045.1

Cited by 10 publications

(9 citation statements)

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“…The variation of these results is far away from the results presented by other authors as James et al [34] whose RMSE had a negligible deviation because of the number of GCPs, obtaining 3.12, 3.57, and 3.59 cm for 5, 10, and 15 GCPs, respectively. Thus, though other authors such as Zimmerman et al [30] found that (7 to 9) wellplaced GCPs in the optimal configuration produced the same magnitude of error as using more (15) poorly placed GCPs, the only acceptable values in our case are those collected by using 10 GCPs, with an IQR less than 3 cm. Moreover, 10 GCPs is just the maximum number of points for this particular case.…”

Section: Influence Of Number Of Gcpscontrasting

confidence: 50%

“…Thus, the synchronous nature of the data is not lost [14]. Photogrammetry has evolved to the technique called structure from motion (SfM) [13][14][15][16][17] based on algorithms that allows one to obtain excellent cartographic results from a set of frames that cover an area. The emergence of RPAS systems as well as the high definition of today's digital cameras have induced new cartographic systems.…”

Section: Introductionmentioning

confidence: 99%

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Beach Leveling Using a Remotely Piloted Aircraft System (RPAS): Problems and Solutions

Contreras-de-Villar

García²,

Muñoz-Pérez

et al. 2020

JMSE

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The size and great dynamism of coastal systems require faster and more automated mapping methods like the use of a remotely piloted aircraft system (RPAS) or unmanned aerial vehicle (UAV). This method allows for shorter intervals between surveys. The main problem for surveying using low-altitude digital photogrammetry in beach areas is their visual homogeneity. Obviously, the fewer the homologous points defined by the program, the lower the accuracy. Moreover, some factors influence the error performed in photogrammetric techniques, such as flight height, flight time, percentage of frame overlap (side and forward), and the number of ground control points (GCPs). A total of 72 different cases were conducted varying these factors, and the results were analyzed. Among the conclusions, it should be highlighted that the error for noon flights is almost double that for the early morning flights. Secondly, there is no appreciable difference regarding the side overlap. But, on the other side, RMSE increased to three times (from 0.05 to 0.15 m) when forward overlap decreased from 85% to 70%. Moreover, relative accuracy is 0.05% of the flying height which means a significant increase in error (66%) between flights performed at 60 and 100 m height). Furthermore, the median of the error for noon flights (0.12 m) is almost double that for the early morning flights (0.07 m) because of the higher percentage of grids with data for early flights. Therefore, beach levelings must never be performed at noon when carried out by RPAS. Eventually, a new parameter has been considered: the relationship between the number of GCPs and the surface to be monitored. A minimum value of 7 GCP/Ha should be taken into account when designing a beach leveling campaign using RPAS.

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Section: Influence Of Number Of Gcpscontrasting

confidence: 50%

Section: Introductionmentioning

confidence: 99%

Beach Leveling Using a Remotely Piloted Aircraft System (RPAS): Problems and Solutions

Contreras-de-Villar

García²,

Muñoz-Pérez

et al. 2020

JMSE

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“…Spring or equinoctial spring tides could have also contributed to the formation of these features in September 2012, October 2014, and November 2015, when they were spotted in the backshore and with similar spacing in the Google Earth satellite imagery (Figure 2b, Table 2). As for the conditions leading to the formation of the features, during summer 2017, the accretionary conditions and the onshore sediment transport led to berm development process in the upper foreshore [42] (see the berm evolution and the formation of a bar in Figure 7a,b), allowing sufficient room for the ulterior formation of both the rhythmic morphologies and a steep beach-face. Their formation was probably linked with spring or equinoctial spring tides and/or longer period waves, processes that may have favored the total water level to reach the backshore.…”

Section: Discussionmentioning

confidence: 99%

“…Despite several artificial nourishment actions having been undertaken in the northern sector of the spit, it is retreating over the medium-term at an average rate of 1 m/year [35]. Proof of this retreating trend are the presence of outcrops of a peat layer at the foreshore, corresponding to fossil salt marshes, the reactivation of the present washover deposits (even during non-storm conditions) [42], and the presence of human infrastructures in the intertidal area, which were originally placed on top of the foredune several decades ago.…”

Section: Study Sitementioning

confidence: 99%

UAS Identify and Monitor Unusual Small-Scale Rhythmic Features in the Bay of Cádiz (Spain)

Talavera¹,

Benavente²,

Río³

2021

Remote Sensing

Self Cite

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Unusual shore-normal and barred-like rhythmic features were found in Camposoto Beach (Bay of Cádiz, SW Spain) during a monitoring program using unmanned aerial systems (UAS). They appeared in the backshore and persisted for 6 months (October 2017–March 2018). Their characteristics and possible formation mechanism were investigated analyzing: (1) UAS-derived high-resolution digital elevation models (DEMs), (2) hydrodynamic conditions, and (3) sediment samples. The results revealed that the features did not migrate spatially, that their wavelength was well predicted by the edge wave theory, and that they shared characteristics with both small-scale low-energy finger bars (e.g., geometry/appearance and amplitude) and swash cusps (e.g., wavelength, seaward circulation pattern, and finer and better sorted material in the runnels with respect to the crests). Our findings pinpoint to highly organized swash able to reach the backshore during spring tides under low-energy and accretionary conditions as well as backwash enhanced by conditions of water-saturated sediment. This study demonstrates that rhythmic features can appear under different modalities and beach locations than the ones observed up to date, and that their unusual nature may be attributed to the low spatiotemporal resolution of the traditional coastal surveying methods in comparison with novel technologies such as UAS.

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“…Spits are common when the coastline presents abrupt changes and longshore transport has a dominant direction creating a converging sediment zone, e.g., downdrift from a jetty or tidal inlet [3,4]. Sand spit growth and evolution are driven by many factors, including an underlying geological framework [5], wave processes [6][7][8], wave approaching angle [9][10][11], swash bar welding [12,13], tidal currents [13], longshore sediment drift [3,14], and overwash events [15,16]. Each process leads to a specific development (or degeneration, e.g., overwash events) of spit geometric characteristics.…”

Section: Introductionmentioning

confidence: 99%

Characterization of the Morphological Behavior of a Sand Spit Using UAVs

Paladio-Hernandez¹,

Salles

Arriaga

et al. 2022

JMSE

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Sand spits are common in wave-dominated environments; with enough sand supply, they can evolve to affect circulation and navigation in channels or inlets. The focus of this paper is on the navigation channel of the Sisal Port, located on the northwestern Yucatan Peninsula (YP) coast, where a sand spit grew and was monitored from its formation (June 2018) until navigation was practically blocked (November 2018). The YP coast is characterized as being microtidal, with significant wave heights ranging from 0.1 to 0.4 m (April to September), and in the presence of high energy events (cold fronts and storms), waves can reach heights of up to 2.5 m offshore at 10 m depth (October to February). Prior to the beginning of UAV surveys, we used photos (June–July 2018) from a stationary field camera and hydrodynamic data from models (WaveWatch III for waves and MARV software for tidal levels) to generate a qualitative description of the sand spit in the channel. Combining products from UAVs flights (DEMs) and hydrodynamic measurements (wave energy flux), we characterized the behavior and response of the sand spit, from its formation near the jetty head, through its consolidation in October 2018, to when a cold front with HS ∼2.5 m breached it in mid-November. The results show that spit formation takes place during calm conditions (e.g., periods dominated by sea breezes), and depending on the energy threshold of high energetic events, this new spit will consolidate or be breached. Migration of the spit is related to overwash events and changes in wave direction. The presented methodology provides a well-rounded tool for characterizing the morphological behavior of spits on a shallow coast, which can be useful for improving coastal management.

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UAS & SfM-based approach to Monitor Overwash Dynamics and Beach Evolution in a Sandy Spit

Cited by 10 publications

References 0 publications

Beach Leveling Using a Remotely Piloted Aircraft System (RPAS): Problems and Solutions

Beach Leveling Using a Remotely Piloted Aircraft System (RPAS): Problems and Solutions

UAS Identify and Monitor Unusual Small-Scale Rhythmic Features in the Bay of Cádiz (Spain)

Characterization of the Morphological Behavior of a Sand Spit Using UAVs

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