Shoreline Variability Research Articles

Shoreline change assessment at Arroio do Sal (Southern Brazil) using different shoreline extraction methods

This research aims to compare different shoreline extraction methods in assessing shoreline variability at Arroio do Sal, Southern Brazil. The methodology included the automatic extraction of shoreline positions by CoastSat and Cassie and the manual vectorization of shorelines using two different shoreline proxies. Digital Shoreline Analysis System was used to compute the shoreline displacement for each extraction method and shoreline mission. The results were compared in terms of rates, uncertainties, and methodologies. The results show that the CoastSat lines are generally displaced towards the land, while Cassie is displaced towards the sea. To concerning shape, Cassie has a more undulating shape and a greater number of indentations, with more exaggerated features, while CoastSat has a more rectilinear line, with smoother indentations next to the washouts. The RMSE values are 8.89 m for CoastSat and 27.27 m for Cassie. Despite the variations in the coastline position between the algorithms, the analyses of the rates of change have similar trends. Both algorithms establish an erosion trend for the Sentinel lines, but with different magnitudes; for the Landsat lines, both algorithms show a stable coastline, with the same average and uncertainty. Arroio do Sal can be considered a stable coastline, with rates of change in the −0.5 m–0.5 m range. Both algorithms were able to determine this general trend.

On the shoreline monitoring via earth observation: An isoradiometric method

Shoreline variations, triggered by climate change, eustatism, and tectonic, drive the coastal landscape evolution over multiple spatial and temporal scales. Among the many different existing coast types, sandy coasts are the most sensitive to coastal erosion and accretion processes and, at the same time, often host valuable anthropogenic assets. The rapid and ongoing evolution of these coastal environments poses challenges for their management, necessitating cost-effective and highly reliable methods for measuring these changes. Many remotely sensed shoreline extraction methods have been proposed in the literature, providing valuable tools for improving coastal management. Even if these methodologies allow the demarcation of the shoreline, its pixelated shape usually requires refinement through subsequent smoothing or vector generalization processes. It is important to note that the position of the thus extracted coastline is not a direct result of a measured physical quantity but rather a product of these refinement techniques. To address this problem, we developed a sub-pixel resolution method for extracting shorelines from remotely sensed images of sandy beaches, leveraging the radiometric signature of the shoreline. Validated through precise Global Navigation Satellite System field surveys for positioning the beach foreshore, this method was successfully applied to three beaches in Sicily, in the central Mediterranean, all exhibiting similar microtidal conditions. Its robust design allows for application across various satellite images, employing a straightforward radiometric interpolation method adaptable to different spatial resolutions. This method would be a valuable tool for coastal managers in detecting and mitigating coastal erosion and developing and maintaining anthropogenic coastal assets.

On the influence of coastal structures on shoreline variability and beach interconnection

Approximately 24 % of sandy beaches worldwide are experiencing erosional processes often driven by natural forces that are intensified by human activities. Erosion becomes a significant issue, particularly when it affects areas of socioeconomic and ecological importance. Thus, this study aimed to utilize coastline data from a city in southern Brazil, extracted from satellite images using free computational tools, with three main objectives: (1) identify spatial and temporal trends and cycles; (2) assess the impact of coastal structures; and (3) identify beach interconnection indicating bypassing processes in sandy beaches. For the first two objectives, shoreline data from 2015 to 2023, as well as statistical data, were extracted using the CASSIE tool. These data were filtered to minimize tidal effects and remove outliers. Subsequently, they were visualized using a Hovmöller diagram to provide a systemic overview. Through this diagram, it was possible to identify sediment transport toward the north and a sub-annual cycle of seasonality, with erosion occurring during the southern hemisphere's spring months, a period characterized by high-energy events. The relationship between erosional/accretional stretches and anthropogenic structures highlighted the negative impact of longitudinal structures, which exacerbated erosional processes, and the limited effectiveness of transverse structures in retaining necessary sediment. Moreover, the detrimental effect of building a jetty on its adjacent beaches was identified due to the alteration of the refraction control point and consequently, the equilibrium state of the beaches, which are unable to adapt due to coastal urbanization. For the third objective, shoreline data detected by the CoastSat tool from 1984 to 2023 were used. These data were subjected to Pearson correlation analysis. Perpendicular barriers to the shoreline that exhibited low correlation indicate limits of circulation cells that prevent the continuous bypassing process. Conversely, high correlation values suggest that the barrier allows for the occurrence of this process.

Satellite-derived sandy shoreline trends and interannual variability along the Atlantic coast of Europe

Monitoring sandy shoreline evolution from years to decades is critical to understand the past and predict the future of our coasts. Optical satellite imagery can now infer such datasets globally, but sometimes with large uncertainties, poor spatial resolution, and thus debatable outcomes. Here we validate and analyse satellite-derived-shoreline positions (1984–2021) along the Atlantic coast of Europe using a moving-averaged approach based on coastline characteristics, indicating conservative uncertainties of long-term trends around 0.4 m/year and a potential bias towards accretion. We show that west-facing open coasts are more prone to long-term erosion, whereas relatively closed coasts favor accretion, although most of computed trends fall within the range of uncertainty. Interannual shoreline variability is influenced by regionally dominant atmospheric climate indices. Quasi-straight open coastlines typically show the strongest and more alongshore-uniform links, while embayed coastlines, especially those not exposed to the dominant wave climate, show weaker and more variable correlation with the indices. Our results provide a spatial continuum between previous local-scale studies, while emphasizing the necessity to further reduce satellite-derived shoreline trend uncertainties. They also call for applications based on a relevant averaging approach and the inclusion of coastal setting parameters to unravel the forcing-response spectrum of sandy shorelines globally.

Evaluating and predicting coastal shoreline changes in the Doi Duong - Phan Thiet beach area by remote sensing and GIS technology

Assessing the shoreline variability is paramount in understanding the erosion and coastal accretion processes. The potential impact of erosion on coastal communities, particularly in coastal regions, amplifies the vulnerability to coastal disasters. In this study, Landsat satellite imagery captured from 1990 to 2022 was utilized, in conjunction with Geographic Information System (GIS), to scrutinize alterations in the shoreline of Doi Duong Beach - Phan Thiet. The satellite images were independently processed using aspect-ratio methods and thresholding techniques to determine the prevailing condition of the coastline. The rate of shoreline change was quantified using the DSAS tool. The investigation’s findings reveal a dynamic interplay between erosion and accretion, with accretion dominance explicitly evident within the areas surrounding the Ca Ty - Phu Hai river mouth. The average annual shoreline change rate is 27.1 m/yr for the Ca Ty River mouth and 16.5 m/yr for the Phu Hai River mouth. The most significant disparity between the recorded coastline in 1990 and 2022 measures 868 m. Additionally, the projections for the coastline until 2032 indicate that accretion remains the dominant process. This research shows that combining geospatial techniques and numerical models is a reliable way to study shoreline change trends.

Inlet-adjacent beach and shoreline variability at decadal scales

Beaches provide storm protection and economic benefit for coastal communities and also host important habitats for keystone species, especially in the state of Florida. However, sea level rise, coastal construction, and intensifying storms are resulting in coastal erosion, which often requires informed mitigation and management strategies. This study aims to explore decadal-scale trends in morphology change and shoreline variability of inlet-adjacent beaches in Jupiter, Florida. Data from three locations over a period of three decades were analyzed to determine volumetric and contour changes above the shoreline (0 m elevation) and across the entire profile. The largest variability in decadal morphology change was measured at beaches closest to Jupiter Inlet. Substantial shoreline and beach changes were also associated with periods of higher storm activity. Variability in storm events, nourishment trends, and longshore sediment transport also influenced decadal morphologic change. To best adapt to coastal change and develop comprehensive beach-inlet management plans, it is imperative to understand past trends of shoreline variability and beach-nearshore erosion and accretion patterns. Results of this study demonstrate an approach to elucidate decadal patterns in morphology changes and drivers of change.

Impacts of anthropogenic structures in long- and short-term shoreline evolution of Santa Marta Bay (Colombian Caribbean)

Interaction of Anthropic interventions (rigid structures) with coasts is an essential aspect for understanding their geomorphic evolution and incorporating these data into adequate coastal management. This study analyses the short and long-term behavior (1985 to 2019) of shoreline at Santa Marta Bay (Caribbean - Colombia) and their relationship with coastal protection structures. The shoreline variations were analyzed through aerial photographs and satellite images using DSAS tools. The short-term assessment showed initial intense 1985–1991 erosion, with an average retreat speed rate of − 1.6 m·y− 1. It changed gradually since 2003, due to the construction of rigid structures and beach nourishment, decreasing shoreline retreat and even a progradation rate of 0.2 m·y− 1 was observed. The 2009–2019 period, despite recording a positive average value, exhibited a high percentage of erosion profiles. Therefore, in a decadal or long-term analysis (1985–2019), despite engineering works present positive results in the short term, new interventions are required. The coastal erosion is not uniform along the shoreline, because the area is a closed bay with small sediment inputs, the variations in erosion and accretion rates change with human intervention and the installation of new structures. Therefore, quantifying the scale and rate of shoreline changes and correlating them with anthropogenic structures is an essential step in assessing shoreline vulnerability.

Geospatial analysis of shoreline and areal dynamics in the Ganges deltaic island of Bangladesh using the GIS-DSAS technique

Manpura Island, located at the mouth of the Ganges-Brahmaputra-Meghna (GBM) River estuary, is a well-known Ganges deltaic island prone to severe erosion. This study aims to identify shoreline and areal changes in Manpura Island of Bangladesh from 1990 to 2020 using the digital shoreline analysis system (DSAS), a plugin of ArcGIS. The estimation of shoreline variability was primarily described for four segments of the Island: Segment A in the north, Segment B in the west, Segment C in the south, and segment D in the east. It was observed that all four segments of the study area are vulnerable to high rates of shoreline erosion. Landward movement was high in Segment A where Net Shoreline Movement (NSM) was −4000.1 m. Landward movement was also high in Segments B and C with the NSM of −1084.7 m and −1021.6 m, respectively. According to the End Point Rate (EPR) and Linear Regression Rate (LRR), Segment A exhibited a very dynamic feature, with an average shoreline change rate of −24.7 m/yr and −24.2 m/yr, respectively. In Segment C, the average shoreline change rate was −8.5 m/yr for EPR and −9.1 m/yr for LRR. Approximately 392 transects were constructed in the four segments of the island, with approximately 330–334 showing landward movement and 58–62 showing seaward movement. Nevertheless, the island lost about 28.4 km2 in land area and gained only around 2.3 km2 of its original landmass during the study period. The total loss of shoreline length was about 11.5 km (0.4 km/yr), while the total loss of land area was about 26.1 km2 (0.9 km2/yr). The main factors of shoreline change in the study region is likely to be high river discharge, stormy climate and, human interference. The results of this study are useful for the proper management and planning of Manpura Island. However, they can also be used in statistical approaches to forecasting possible shoreline locations in the future under double pressure of climate change and human activities.

Assessment of Shoreline Change from SAR Satellite Imagery in Three Tidally Controlled Coastal Environments

Coasts are continually changing and remote sensing from satellites has the potential to both map and monitor coastal change at multiple scales. Unlike optical technology, synthetic aperture radar (SAR) is uninfluenced by darkness, clouds, and rain, potentially offering a higher revision period to map shoreline position and change, but this can only be feasible if we have a better interpretation of what shorelines as extracted from SAR imagery represent on the ground. This study aims to assess the application of shorelines extracted from SAR from publicly available satellite imagery to map and capture intra-annual to inter-annual shoreline variability. This is assessed in three tidally controlled coastal study areas that represent sand and gravel beaches with different backshore environments: low-lying dunes and marsh; steep, rocky cliff; and urban environments. We have found that SAR shorelines consistently corresponded to positions above the high-water mark across all three sites. We further discuss the influence of the scene geometry, meteorological and oceanographic conditions, and backshore environment and provide a conceptual interpretation of SAR-derived shorelines. In a low-lying coastal setting, the annual change rate derived through SAR presents a high degree of alignment with the known reference values. The present study contributes to our understanding of the poorly known aspect of using shorelines derived from publicly available SAR satellite missions. It outlines a quantitative approach to automatically assess their quality with a new automatic detection method that is transferable to shoreline evolution assessments worldwide.

Contribution of remote sensing and GIS in the study of the evolution of Anza beach in Agadir (Morocco)

The Moroccan coastline, in particular the Atlantic coast, presents a unique geographical and environmental context that requires special attention. Beaches in this region are subject to natural and anthropogenic forces that influence their dynamic evolution. This study focuses on the in-depth analysis and monitoring of Anza beach in Agadir, Morocco. The aim is to provide an in-depth understanding of the evolution of the Anza coastline. Shoreline analysis quantifies shoreline variations and changes over time using the Digital Shoreline Analysis System tool (DSAS). This analysis provides important information on the erosion and accumulation processes that influence the stability of Anza beach.

Impact of ebb-delta dynamics on shoreline evolution along inlet-interrupted coasts

Shorelines adjacent to tidal inlets are highly dynamic landforms affected by oceanic (e.g., sea-level rise) and terrestrial (e.g., fluvial sediment supply) processes. Climate change is thus expected to have substantial physical impacts on these inlet-interrupted coasts. Numerical simulation of such impacts requires a holistic approach where at least the major governing processes that affect the local sediment budget are considered. The Generalized-Scale-aggregated Model for Inlet-interrupted Coasts (i.e., G-SMIC) is such a model that is capable of holistically simulating the evolution of inlet-interrupted coasts over multi-decadal to century time periods. However, in its present form, G-SMIC does not consider the effects of ebb-delta dynamics in its computations. Here, we improve the model to include ebb-delta dynamics and pilot the improved model (G-SMIC+) at two selected case study sites in Vietnam (Thu Bon estuary) and Wales, United Kingdom (Mawddach estuary). Model hindcasts of G-SMIC+ at both case study locations show reasonable agreement with available records of shoreline variations. The evolution of the two inlet-estuary systems was assessed over the 21st century under four of the IPCC’s sixth assessment report climate scenarios (viz., SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5). Results show that both systems switch between sediment exporting and sediment importing systems over the study period (2031 - 2100). Moreover, while the inclusion of ebb-delta dynamics may decrease the erosion volumes of the up-drift shoreline by up to 37% and 46% at Thu Bon and Mawddach estuaries, respectively (by 2100, relative to 2030), the down-drift coast is only affected in a noticeable way at the Mawddach estuary, where the accretion volume is projected to reduce by ~50%. As a result, the ebb-delta effect decreases the up-drift shoreline retreat by up to 37% and 48% at Thu Bon and Mawddach estuaries, respectively, while it reduces shoreline progradation of the down-drift coast of Mawddach estuary by up to ~50%. These results highlight the importance of including ebb-delta dynamics in modelling efforts to assess the climate change responses of inlet-interrupted coasts worldwide.

Role of Atmospheric Indices in Describing Shoreline Variability Along the Atlantic Coast of Europe

AbstractBeaches are highly variable environments and respond to changes in wave forcing, themselves modulated by climate variability. Here, we analyze three high‐quality beach profile data sets to robustly investigate, for the first time, the link between shoreline change, wave forcing and climate variability along the Atlantic coast of Europe. Winter wave conditions are strongly associated with North Atlantic Oscillation (NAO) and Western Europe Pressure Anomaly (WEPA), with WEPA explaining 50%–80% of the winter wave power variability. Shoreline variability during winter is also strongly linked to NAO and WEPA, with WEPA explaining 25% of the winter shoreline variability. Winter wave conditions and associated shoreline variability are both unrelated to El Nino Southern Oscillation. In addition to the atmospherically‐forced beach morphological response, shoreline change also depends strongly on the antecedent morphology as evidenced by significant correlations between summer/winter shoreline response and the shoreline position at the start of each season.

A multi-scale assessment of shoreline changes at an undeveloped beach in southern Brazil

This research aims to investigate shoreline variability at an undeveloped beach in southern Brazil on interannual and millennial scales. The long-term coastal evolution was investigated by GPR, whereas the interannual scale shoreline changes were analyzed by the Digital Shoreline Analysis System (DSAS). Simultaneously, a supervised Maximum Likelihood image classification was applied to the dune systems to differentiate vegetation from sand. The results show that the coastline in the Praia das Cabras region is retreating at different scales. The stratigraphic record in GPR shows that the coast has a retrogradational stacking pattern behavior in geological time. At the same time, the results obtained from the digital shoreline analysis revealed that the coast has suffered short-term erosion in the analyzed period, and this is attributed to natural causes. Another point is the higher values of erosion in the extreme parts of the study area, which are related to the presence of washouts. There is also a differentiation in the stage of the dunes and vegetation between the northern and southern parts of the stretch. The northern area is more densely vegetated and has a continuous foredune ridge with incipient dunes forming a ramp, whereas in the southern part, the vegetation is more dispersed, with interrupted dunes forming nebkhas. Between 2019 and 2023 there was a recovery of the dune field, by filling in the blowouts and minimizing the indentations, forming a more homogeneous foredune line.

INFLUENCE OF EBB-DELTA DYNAMICS ON EVOLUTION OF INLET-INTERRUPTED COASTS

Shoreline variation along inlet-interrupted coasts in macro-time scales can be addressed as a sediment budget-related process, and it was first presented by Ranasinghe et al. (2013) as the Scale-aggregated Model for Inlet-interrupted Coasts (i.e., SMIC). This was further developed as the Generalised Scale-aggregated Model for Inlet-interrupted Coasts (i.e., G-SMIC) by Bamunawala et al. (2020a, 2020b, 2021). The G-SMIC is a fully probabilistic, generically applicable model that simulates the evolution of inlet-interrupted coasts under climate-change impacts and anthropogenic activities. However, G-SMIC does not consider any ebb-deltas in the vicinity of inlet-estuary systems. Thus, this study aims to include the ebb-delta dynamics into the G-SMIC so that its generic applicability would further increase.

Early morphodynamics of the sudden formation of beaches during the 2021 volcanic eruption of La Palma

On 19 September 2021, a new Strombolian monogenetic volcano erupted on the island of La Palma (Canary Islands, Spain). During the 12-week eruption, a succession of lava flows progressed down the west-central slopes, descended down the coastal cliffs and advanced over a narrow island shelf, filling it in the form of lava deltas. After the stabilization of the lava deltas, the formation of beach-like sedimentary bodies could be observed. This works aims to document the rhythms and formation dynamics of these beaches in the first months after their emergence using orthophotographic materials obtained using unmanned aerial vehicles (UAVs). These technologies have allowed analysis of the subaerial coastal evolution of the lava deltas between October 2021 and May 2022 through high-resolution digital images of approximately weekly frequency. The study includes analyses of the dichotomous evolution (emergences, disappearances, disintegrations and coalescences), short-term surface and shoreline variability (by rates of variation, Shoreline Change Envelope and Net Shoreline Movement indicators) and medium-term surface and shoreline trends (by linear regressions and End Point Rate indicators). The observations show that the formation of shoreline sedimentary bodies was sudden, within 24–48 h after stabilization of the lava fronts, and that most were subsequently long-lasting. Despite their durability, the dynamics after their appearance show high morphological mutability. The analysis of the maritime regime has allowed us to interpret these early, abnormally changing dynamics as initial states of morphodynamic disequilibrium and adjustments towards morphological stability and equilibrium with the physical environmental conditions.

Interannual variability in dominant shoreline behaviour at an embayed beach

Shoreline variability at embayed beaches can be characterized into modes where either longshore or cross-shore sediment transport processes dominate the overall shoreline response, or there is a mixed combination of the two. To-date it has been assumed that the relative dominance of these differing modes of longshore and/or cross-shore shoreline behaviour is stationary in time. This concept is tested using a unique 43-year dataset of shoreline positions at Narrabeen-Collaroy beach (southeast Australia) and a rolling five-year window Empirical Orthogonal Function analysis, revealing the new observation of a distinct interannual variability in the dominant cross-shore and longshore modes of shoreline behaviour at this site. The dominant mode of shoreline behaviour was found to range from time periods when the cross-shore mode (referred to as the cross-shore coherent mode) comprised as much as 74 % of the overall shoreline variability, contrasting to other time periods when the alongshore mode of shoreline behaviour (longshore coherent mode) was more dominant, accounting for up to 62 % of the observed shoreline variability. Wave forcing correlation analysis suggests that these modes are controlled by varying influences of wave intensity and wave direction at interannual time scales. Consistent with previous research at this same embayment, the cross-shore coherent mode of shoreline variability appears to be controlled primarily by wave height/intensity, with stronger controls (i.e., higher correlation) when this cross-shore mode was overwhelmingly dominant. In contrast, the contribution of the longshore coherent mode appears to be controlled primarily by wave direction, but also at certain unique times in the time series by wave intensity. Analysis using available topographic and bathymetric data suggests that the observed switch in longshore versus cross-shore dominance may be triggered by extreme storm events, which cause significant and near ‘instantaneous’ redistribution of sediment across the entire shoreface and beach face. These results highlight the importance of considering a non-stationary shoreline behaviour at embayed beaches and the association of differing modes of dominant shoreline behaviour with interannual wave climate variability. Given observed interannual variability in deep water wave climates more broadly, it is likely that the dominant modes of shoreline variability may also occur at other embayed beaches and should be considered for numerical modelling (and prediction) of future shoreline behaviour.

Assessment of the Impact of Anthropogenic Evolution and Natural Processes on Shoreline Dynamics Using Multi-Temporal Satellite Images and Statistical Analysis

This research aims to examine changes in the eastern part of Qatar’s shoreline from 1982 to 2018 by means of satellite imagery. Five different time periods, namely 1982, 1992, 2002, 2013, and 2018, were analysed to determine shoreline movements and shoreline variations. Techniques such as maximum likelihood classification, the normalised difference vegetation index, and tasselled cap transformation were utilised to extract the shoreline data. Linear regression rate statistics were used to quantify the rate of shoreline variations. The results indicate that the majority of shoreline accretion is a result of human activities such as coastal construction, land reclamation, and building artificial islands, which are associated with the high economic activity over the past two decades. Significant changes were observed in Lusail City, The Pearl, and Hamad International Airport (HIA). Natural sediment accumulation was also observed in Al Wakra and on the southern side of HIA. In general, there were more land gains than losses throughout the study period, and the shoreline increased by twice its previous length. The field survey confirmed the presence of sandy and rocky beaches, as well as a shoreline with protective structures such as natural limestone rocks and concrete reinforcement.

Pacific shoreline erosion and accretion patterns controlled by El Niño/Southern Oscillation

In the Pacific Basin, the El Niño/Southern Oscillation (ENSO) is the dominant mode of interannual climate variability, driving substantial changes in oceanographic forcing and impacting Pacific coastlines. Yet, how sandy coasts respond to these basin-scale changes has to date been limited to a few long-term beach monitoring sites, predominantly on developed coasts. Here we use 38 years of Landsat imagery to map shoreline variability around the Pacific Rim and identify coherent patterns of beach erosion and accretion controlled by ENSO. On the basis of more than 83,000 beach transects covering 8,300 km of sandy coastline, we find that approximately one-third of all transects experience significant erosion during El Niño phases. The Eastern Pacific is particularly vulnerable to widespread erosion, most notably during the large 1997/1998 El Niño event. By contrast, La Niña events coincide with significant accretion for approximately one-quarter of all transects, although substantial erosion is observed in southeast Australia and other localized regions. The observed regional variability in the coastal response to ENSO has important implications for coastal planning and adaptation measures across the Pacific, particularly in light of projected future changes in ENSO amplitude and flavour. The El Niño/Southern Oscillation drives coherent patterns of beach erosion and accretion around the Pacific Rim, according to analysis of satellite imagery covering over 8,300 km of sandy coastline.

Diagnostic modeling of the shoreline variation along the Jiangsu Coast, China

Intertidal flats are of great socio-economic and ecological importance in defending the coastal cities from flooding, providing resources for land reclamations and habits for wildlife. On the intertidal flats, milder profiles are usually featured with finer sediment. However, we find the opposite relationship between the alongshore variation in intertidal slope and sediment grain size on the intertidal flat along the Jiangsu Coast. With a conceptual figure of the hydrodynamics and shoreline evolution on this coast, we hypothesize that the unexpected pattern is caused by the alongshore gradient in hydrodynamic forcing. In order to test our hypothesis, we carry out a series of numerical model simulations in a highly schematized manner to investigate the real mechanism behind this unexpected pattern. Through the analysis, we find that only the southwards coarsening pattern is inconsistent with the shoreline evolution pattern. This inconsistency is not induced by alongshore hydrodynamic gradient, and can only be explained by different sediment provenances. We also find that the alongshore shoreline evolution pattern is not only determined by the alongshore gradient in hydrodynamic forcing, but also influenced by the alongshore variation in bed composition. In the erosion/sedimentation transition zone, the bed composition factor plays the major role.

Lichens as an Indicator of Sea-Level Rise

Coastal areas around the globe are threatened with sea-level rise (SLR). Many of these areas support coastal forests, and determining the threat is complicated by wind patterns and sea floor and shoreline variability, beyond simple elevational concerns. Lichens can be used as indicators of SLR at site specific locations. Developing vegetative indicators of SLR could assist land managers, municipalities, and homeowners in evaluating the risk of building homes, roads, and other structures in some locations. The absence of salt sensitive lichen species can be an indicator of SLR potential. We base this on lichen distribution patterns within two Florida state parks – one a barrier island, the other on the nearby mainland. Rapidly colonizing lichen taxa with asexual reproductive structures are poor indicators of SLR, because of their ability to quickly recolonize following storm events and other disturbances. Knowledge of lichen distribution patterns in combination with reproductive traits help facilitate the development of lichen indicator guidelines. We have learned that Coccocarpia palmicola, Dirinaria picta, and Heterodermia albicans do not appear to be salt-tolerant but have abundant asexual propagules and recolonize rapidly. Sites lacking salt sensitive lichens such as Bulbothrix laevigatula, Cryptothecia rubrocincta, Leptogium cyanescens and Parmotrema rampoddense could indicate areas that are at high risk to SLR at a fine scale. Such areas should be avoided for the construction of homes, roads, and other structures. Lichens make good indicator species and could help guide management of coastal areas in Florida and much of the U.S. southeast Coastal Plain.