Coastal Elevation Research Articles

Coastal Vulnerability Index (CVI) Assessment: Evaluating Risks Associated with Human-Made Activities along the Limassol Coastline, Cyprus

Coastal risk assessment is crucial for coastal management and decision making, especially in areas already experiencing the negative impacts of climate change. This study aims to investigate the coastal vulnerability due to climate change and human activities in an area west of the Limassol district’s coastline, in Cyprus, on which there have been limited studies. Furthermore, an analysis is conducted utilising the Coastal Vulnerability Index (CVI) by exploiting eight key parameters: land cover, coastal slope, shoreline erosion rates, tidal range, significant wave height, coastal elevation, sea-level rise, and coastal geomorphology. These parameters were assessed utilising remote sensing (RS) data and Geographical Information Systems (GISs) along a 36.1 km stretch of coastline. The results exhibited varying risk levels of coastal vulnerability, mainly highlighting a coastal area where the Kouris River estuary is highly vulnerable. The study underscores the need for targeted coastal management strategies to address the risks associated with coastal erosion. Additionally, the CVI developed in this study can be exploited as a tool for decision makers, empowering them to prioritise areas for intervention and bolster the resilience of coastal areas in the face of environmental changes.

Imprints of washover sediments by tropical storm Pabuk 2019 along the coast of the Gulf of Thailand; insight into coastal geomorphological response to storm surge

Tropical storm Pabuk (4th January 2019) struck southern Thailand, causing damage to the low-lying coastal area. The combination of waves, storm surge, and high tide resulted overwash and inundation of regions on the West coast of the Gulf of Thailand (GOT) side. After the event, we conducted a field survey from January 7–10 and 15–20, 2019 to investigate the effect of storm surges and the degree of damage from the site under the eye of storm affected area up to the north 500 km from the landfall sites. This paper investigates how variations in coastal geomorphological features respond to the storm surge generated by tropical storm Pabuk at a regional scale. Coastal damage was observed along the beach from the presence of the scour, beach scarp, knocked down trees, and destroyed buildings and infrastructure. The most damaged area was at Nakhon Si Thammarat (NST), where the tropical storm made landfall with maximum wind speeds of almost 100 km/h and a storm surge height of 5 m. At NST site, the washover deposits extended as far as 80 m from the coastline with a maximum inundation of 330 m. From this study, two types of washover deposits including perched fan and washover terrace were identified. The thickest washover sediment, 60 cm thick, was discovered in a relatively low-lying area adjacent to a small estuary. Mud rip-up clasts, planar stratification, cross stratification, foreset bedding, scouring at base, and sharp and erosional contact are characteristics of sedimentary structures found in storm sediments. Bedform surfaces, such as current ripples with indicated storm surge direction, were well-preserved at several sites. We suggest that the local geomorphological controlling factors, especially coastal elevation have played important roles in the difference of coastal geomorphological responses as well as the type of washover deposits.

Coastal vulnerability assessment to multi hazards in the exposed coast of Southeastern Coastal Region of Bangladesh

Bangladesh is a maritime nation situated on the northern side of the Bay of Bengal (BoB), blessed with substantial natural resources and opportunities. However, natural disasters and climate-induced hazards are threatening these opportunities as well as destroying the recourses. Coastal vulnerability assessment aids in the prevention of loss of life and resource devastation since it provides forewarning of impending calamitous consequences and facilitates taking mitigative measures. The study has endeavored to make a composite coastal vulnerability index (CVI) for the exposed coast of the southeastern coastal region of Bangladesh, combining physical and social vulnerability indexes using several physical and social parameters. The CVI was developed by using nine physical parameters, namely (a) Coastal Elevation, (b) Coastal Slope, (c) Annual Average Rainfall, (d) Storm Surge Height, (e) Soil Salinity, (f) Average Wind Speed, (g) Rate of SLR, (h) Soil Permeability, (i) Mean Tidal Range and six social parameters namely (a) Literacy rate, (b) Household Structure, (c) Land Use Land Cover (LULC), (d) Population Density (e) Number of Disabled People and (f) Number of Population (Age: <5 & >65). With the aid of field and secondary data, thematic layers of each physical and social parameter were prepared by defining five distinct vulnerability classes (i.e., very high, high, moderate, low, and very low) and assigning vulnerability ranks. The final CVI was estimated using geospatial techniques such as GIS and remote sensing, coupled with Physical Vulnerability Index (PVI) and Social Vulnerability Index (SVI), and relevant values were categorized into five distinct groups as before. The findings show that 25.9% of the exposed coast in the southeast coastal region, which comprises Banshkhali, Chakaria, Maheshkhali, and Cox's Bazar Sadar is high to very high vulnerable to multiple hazards. Comparatively, 28.29% have been classified as moderately vulnerable, and the remaining 45.8% in the areas of Hathazari, Mirsharai, Sitakunda, Sandwip, and Chittagong City (Kotwali), Kutubdia show that they are very low to low vulnerable to such multi-hazards. Based on this vulnerability assessment result, sustainable coastal management policy-making and development planning can be taken to mitigate the risk and loss of the southeastern coastal region due to climatic hazards and natural disasters such as floods and storm surges. The outcome information will also help to make an Integrated Coastal Zone Management (ICZM) plan for the proper and sustainable utilization of the coastal resources. Additionally, it will assist as ground information to establish a framework for prioritizing community resilience-building initiatives or developing appropriate adaptation strategies to lower catastrophe risk.

DeltaDTM: A global coastal digital terrain model

Coastal elevation data are essential for a wide variety of applications, such as coastal management, flood modelling, and adaptation planning. Low-lying coastal areas (found below 10 m +Mean Sea Level (MSL)) are at risk of future extreme water levels, subsidence and changing extreme weather patterns. However, current freely available elevation datasets are not sufficiently accurate to model these risks. We present DeltaDTM, a global coastal Digital Terrain Model (DTM) available in the public domain, with a horizontal spatial resolution of 1 arcsecond (∼30 m) and a vertical mean absolute error (MAE) of 0.45 m overall. DeltaDTM corrects CopernicusDEM with spaceborne lidar from the ICESat-2 and GEDI missions. Specifically, we correct the elevation bias in CopernicusDEM, apply filters to remove non-terrain cells, and fill the gaps using interpolation. Notably, our classification approach produces more accurate results than regression methods recently used by others to correct DEMs, that achieve an overall MAE of 0.72 m at best. We conclude that DeltaDTM will be a valuable resource for coastal flood impact modelling and other applications.

Coastal vulnerability assessment along the coast of Kerala, India, based on physical, geological, and socio-economic parameters

The increase in population and rapid economic development activities increase vulnerability along the coastal areas. Coastal zones are among the planet’s most dynamic regions and are susceptible to natural and anthropogenic hazards. To comprehend how risks and hazards are distributed spatially along the coast, coastal vulnerability assessment is crucial. This study aims at identifying the vulnerable zones along the coast of Kerala, India. For this, the coastal vulnerability index (CVI) is calculated by considering the physical, geological, and socio-economic parameters. The physical-geological parameters considered are nearshore bed slope, shoreline change rate, coastal elevation, tidal range, and continental shelf width. The socio-economic parameters include population density, road network, and land use/land cover. Analytical hierarchy process (AHP) is used for obtaining weights for physical-geological and socio-economic parameters. Coastal vulnerability results show that 82.40 km of the coastal stretch has a very high CVI value along the coast of Kerala, accounting for 13.87% of the total coastline. The most vulnerable stretches are along the coast of Kozhikode, Malappuram, Thrissur, Ernakulam, Alappuzha, and Trivandrum districts while Kasargod and Kannur districts have no coastal stretches with very high CVI. High population density, low nearshore bed slope, low coastal elevation, high erosion rates, built-up areas, and roads near to the coastline are some of the factors contributing to very high CVI in coastal districts of Kerala.

Variability in terrestrial characteristics and erosion rates on the Alaskan Beaufort Sea coast

Arctic coastal environments are eroding and rapidly changing. A lack of pan-Arctic observations limits our ability to understand controls on coastal erosion rates across the entire Arctic region. Here, we capitalize on an abundance of geospatial and remotely sensed data, in addition to model output, from the North Slope of Alaska to identify relationships between historical erosion rates and landscape characteristics to guide future modeling and observational efforts across the Arctic. Using existing datasets from the Alaska Beaufort Sea coast and a hierarchical clustering algorithm, we developed a set of 16 coastal typologies that captures the defining characteristics of environments susceptible to coastal erosion. Relationships between landscape characteristics and historical erosion rates show that no single variable alone is a good predictor of erosion rates. Variability in erosion rate decreases with increasing coastal elevation, but erosion rate magnitudes are highest for intermediate elevations. Areas along the Alaskan Beaufort Sea coast (ABSC) protected by barrier islands showed a three times lower erosion rate on average, suggesting that barrier islands are critical to maintaining mainland shore position. Finally, typologies with the highest erosion rates are not broadly representative of the ABSC and are generally associated with low elevation, north- to northeast-facing shorelines, a peaty pebbly silty lithology, and glaciomarine deposits with high ice content. All else being equal, warmer permafrost is also associated with higher erosion rates, suggesting that warming permafrost temperatures may contribute to higher future erosion rates on permafrost coasts. The suite of typologies can be used to guide future modeling and observational efforts by quantifying the distribution of coastlines with specific landscape characteristics and erosion rates.

Coastal erosion and climate change: A review on coastal-change process and modeling.

Coastal erosion is a normal process of nature. However, the rate of coastal erosion, and the frequency and intensity of coastal flooding events, are now on the rise around the world due to the changing climate. Current responses to coastal erosion are primarily determined by site-specific factors, such as coastal elevation, coastal slope, coastal features, and historical coastline change rate, without a systematic understanding of the coastal-change processes in the context of climate change, including spatiotemporal changes in sea level, regional changes in wave climate, and sea ice coverage. In the absence of a clear understanding of the coastal-change processes, most of the current coastal responses have been built upon a risky assumption (i.e., the present-day coastal change will persist) and are not resilient to future climate change. Here, we conduct a literature review to summarize the latest scientific understanding of the coastal-change processes under climate change and the potential research gaps towards the prediction of future coastal erosion. Our review suggests that a coupled coastal simulation system with a nearshore wave model (e.g., SWAN, MIKE21, etc.) can play a critical role in both the short-term and long-term coastal risk assessment and protective measure development.

COASTAL VULNERABILITY ANALYSIS IN DUMAI BARAT DISTRICT

The Coastal area is an area that is very vulnerable to the phenomenon of natural change. The coastal area's vulnerability level is influenced by geological variables, namely coastal geomorphology, sea level rise, shoreline changes, tides, and coastal elevations. This research was conducted in October 2021. This study aims to determine the level of coastal vulnerability in the Dumai Barat Sub-District, Riau Province with a quantitative descriptive method. Based on the result of the study, the coastal vulnerability index can be classified into five categories: very not vulnerable, not vulnerable, medium, high, and very high. The coastal area of Dumai Barat District is categorized as low vulnerability

Predicting future coastal land use/cover change and associated sea-level impact on habitat quality in the Northwestern Coastline of Guinea-Bissau

The assessment of coastal land use/cover (LULC) change is one of the most precise techniques for detecting spatio-temporal change in the coastal system. This study, integrated Land Change Modeler, Habitat Quality Model, and Digital Shoreline Analysis System, to quantify spacio-temporal coastal LULC change and driving forces between 2000 and 2020. Combined the CA-Markov Model with Sea Level Affecting Marshes Model (SLAMM), merged local SLR data with future representative concentration pathway (RCP8.5) scenarios, and predicted future coastal LULC change and associated sea-level rise (SLR) impact on the coastal land use and habitat quality in short-, medium- and long-term. The study area had significant coastal LULC change between 2000 and 2020. The tidal flats, whose change was driven mainly by sea level, registered a total net gain of 57.93 km2. We also observed the significant loss of developed land whose change was influenced by tidal flat with a total loss of −75.58 km2. The tidal flat will experience a stunning net gain of 80.55 km2 between 2020 and 2060, making developed land the most negatively impacted land in the study area. The study led to the conclusion that the uncontrolled conversion of saltmarshes, mixed-forest, and mangroves into agriculture and infrastructures were the main factors affecting the coastal systems, including the faster coastal erosion and accretion observed during a 20-year period. The study also concluded that a low coastal elevation of −1 m and a slope of less than 2° have contributed to coastal change. Unprecedented changes will unavoidably pose a danger to coastal ecological services, socioeconomic growth, and food security. Timely efforts should be made by establishing sustainable mitigation methods to avoid the future impact.

Coastal Vulnerability Assessment of Bali Province, Indonesia Using Remote Sensing and GIS Approaches

Coastal zones are considered to be highly vulnerable to the effects of climate change, such as erosion, flooding, and storms, including sea level rise (SLR). The effects of rising sea levels endanger several nations, including Indonesia, and it potentially affects the coastal population and natural environment. Quantification is needed to determine the degree of vulnerability experienced by a coast since measuring vulnerability is a fundamental phase towards effective risk reduction. Therefore, the main objective of this research is to identify how vulnerable the coastal zone of Bali Province by develop a Coastal Vulnerability Index (CVI) of areas exposed to the sea-level rise on regional scales using remote sensing and Geographic Information System (GIS) approaches. This study was conducted in Bali Province, Indonesia, which has a beach length of ~640 km, and six parameters were considered in the creation to measure the degree of coastal vulnerability by CVI: geomorphology, shoreline change rate, coastal elevation, sea-level change rate, tidal range, and significant wave height. The different vulnerability parameters were assigned ranks ranging from 1 to 5, with 1 indicating the lowest and 5 indicating the highest vulnerabilities. The study revealed that about 138 km (22%) of the mapped shoreline is classified as being at very high vulnerability and 164 km (26%) of shoreline is at high vulnerability. Of remaining shoreline, 168 km (26%) and 169 km (26%) are at moderate and low risk of coastal vulnerability, respectively. This study outcomes can provide an updated vulnerability map and valuable information for the Bali Province coast, aimed at increasing awareness among decision-makers and related stakeholders for development in mitigation and adaptation strategies. Additionally, the result may be utilized as basic data to build and implement appropriate coastal zone management.

Propuesta metodológica para la caracterización y tipificación de las costas españolas. Aplicación a las costas de Galicia.

Hay varias clasificaciones costeras. La mayoría de ellas han sido elaboradas a nivel mundial utilizando criterios tectónicos, climáticos, topográficos u oceanográficos. Otras clasificaciones han sido elaboradas a mayor escala y han sido enfocadas a catalogar las formas costeras: acantilados, playas, estuarios, lagunas o complejos dunares.Este trabajo analiza los tipos de litoral, entendiendo como tal cada sector que presenta determinadas condiciones topográficas marcadas por la elevación y pendiente, y que se modeló sobre un tipo concreto de roca en un entorno climático y marino específico. Se describe un enfoque metodológico para una clasificación a escala detallada. Este enfoque se basa en la delimitación de los diferentes sistemas costeros, ejemplificados en acantilados y playas de cantos rodados, playas de arena y dunas. En este caso las plataformas costeras, marismas y lagunas no han sido consideradas por los problemas técnicos derivados de la fuente de datos LiDAR, de la cual se derivan los modelos digitales del terreno (MDT) de resolución espacial de 2 m.El primer paso en la clasificación fue una delimitación manual que combinaba MDT y ortofotografías. Posteriormente, se realizó otra tipificación mediante la creación automática de Unidades Topográficas Litorales (UTC). Este índice es la combinación de dos variables: elevación costera y pendiente. La posible integración de otras, como la orientación o la litología, es posible, pero generan un número muy elevado de unidades y dificultan su interpretación. Por esta razón, este estudio no consideró más variables.En este proyecto se generaron 30 UTC, y luego se seleccionaron solo aquellas que aparecen en los sectores de acantilados, playas de cantos rodados, playas de arena y dunas costeras. La posibilidad de visualizar una o varias UTC en cualquier sector de la costa permite conocer con mayor precisión las condiciones de cada sector y estas categorías podrían mejorar los planes de gestión costera.

Coastal Vulnerability Assessment: A case study of the Ratnagiri coast, Maharashtra, India

The coastal zone is a vulnerable habitat that needs extra caution to protect ecosystems. Coastal systems are increasingly threatened by possible climate change consequences, as evidenced by the Intergovernmental Panel on Climate Change’s consecutive assessments. Increased tropical storm occurrences in recent years, in addition to the devastation caused by the tsunami in December 2004, have highlighted the necessity of analyzing the coast’s susceptibility to flooding-induced hazards to get a better knowledge of the factors that generate various hazards and, as a result, reduce the after-effects of future occurrences. The Ratnagiri coast in Maharashtra is prone to erosional hazards, periodic land rehabilitation, and sudden rises in sea level. The main objective is to calculate the CVI (Coastal Vulnerability Index) for the Ratnagiri coast. To analyze the vulnerability of the coastal region, eight risk parameters were used, viz. shoreline change rate, coastal elevation, sea level change rate, coastal slope, tide range, significant wave height, coastal geomorphology, and tsunami arrival height. The coastal vulnerability map was created by categorizing the numerous coastal portions into three vulnerability groups: high, medium, and low, which will aid coastal residents in risk mitigation in the future.

The proposal of the Coast-RiskBySea: COASTal zones RISK assessment for Built environment bY extreme SEA level, based on the new Copernicus Coastal Zones data

Natural hazards and the long-term effects of climate change could have disastrous consequences for urban settlements, in this context, risk assessment is a key factor in supporting urban designers and planners. The research proposes a simplified model for the assessment of coastal risk on built environment expressed in terms of potential, direct and tangible, economic damages. The Coast-RiskBySea (COASTal zones RISK assessment for Built environment bY extreme SEA level) is developed in GIS and the risk is evaluated based on the IPCC AR5 and AR6 frameworks through an equation that combines exposure, vulnerability and hazard. The first step is the creation of the land use grid derived from the Copernicus Coastal Zones database, after which then damage scenarios are calculated using depth-damage functions that enable to translate climate impacts into economic damages (exposure). Vulnerability is then assessed in relation to coastal elevation through the DTM and, finally, climate projections of Extreme Sea Level (ESL) are introduced (hazard). To test and verify the approach, the model is applied to the metropolitan city of Naples, Italy, the results show multiple areas at medium and high risk for ESL events with significant economic impacts. From the output maps it is possible to identify the higher risk areas and to understand how, with significant mitigation actions, the risks could be significantly reduced. In conclusion, the Coast-RiskBySea, as it has been developed with input data characterised by a homogeneous spatial coverage, it can be replicable in all EU coastal zones that dispose of a DTM with adequate vertical accuracy.

Multi-criteria coastal environmental vulnerability assessment using analytic hierarchy process based uncertainty analysis integrated into GIS

Changes in environmental conditions influence vulnerability due to interacting stresses and pressures across the nations and regions. Coastal resources are under severe stress due to climate change, growing trade and commerce, and the human population depends on them. The coastal vulnerability to changing climatic variables has created a major concern at regional, national and global scales. The present model study assessed the coastal vulnerability of the densely populated districts in South India, which are prone to extreme climatic events at a higher frequency. The seven crucial influencing variables that have been selected for the study were sea-level rise, coastal elevation, coastal slope, extreme rainy days, historical shoreline change, tidal range, and geomorphology. The identified variables were ranked by relative importance and linked by weightage using analytical hierarchy process-based uncertainty analysis. Mapped and reclassified variables have been integrated to derive the overall vulnerability using geospatial techniques. The study shows that the coast has experienced high vulnerability to SLR impact, extreme rainfall, geomorphology, and elevation; medium vulnerability to the shoreline change and least vulnerable to coastal slope and tidal range. Of the coastal regions studied, 29% and 14.3% had high vulnerability; 70.5% and 85.7% had medium vulnerability in the two selected densely populated districts (Kancheepuram and Tiruvallur District). Applying geospatial techniques to assess the environmental vulnerability resulted in reliable and informative maps which will serve as a model to determine the critical coastal regions to plan for the conservation and adaptation measures.

Precise Elevation Thresholds Associated with Salt Marsh–Upland Ecotones along the Mississippi Gulf Coast

Coastal marshes provide essential ecosystem services related to biodiversity, water quality, and protection from erosion. As increasing rates of relative sea-level rise affect many coastal marsh systems, a thorough understanding of marsh responses to sea-level change, particularly the migration of marsh–upland boundaries, becomes essential. The goal of this study was to determine precise elevation thresholds associated with coastal marsh, the marsh–upland ecotone, and upland plant communities along Mississippi’s Gulf of Mexico coast (diurnal, microtidal). Elevations (NAVD88) were measured using survey-grade Global Navigation Satellite System solutions integrated with high-precision leveling. Plant species were sampled at approximately 1-m intervals along each of thirty-three transects extending from intermediate marsh through the marsh–upland ecotone. Elevation thresholds associated with plant community change were determined based on relevant quartiles of the data. Probabilities of occurrence of each plant community type were computed for elevations at the centimeter scale. Results indicated transitions from marsh to ecotone and ecotone to upland at elevations of approximately 0.40 m and 0.60 m, respectively. Understanding the precise nature of these centimeter-scale dependencies of marsh vegetation on coastal elevation will facilitate spatial modeling of marsh transgression in response to sea-level rise, subsidence, changes in sediment flux, and land use change.

Coastal Hazards of Tropical‐Like Cyclones Over the Mediterranean Sea

AbstractMedicanes, for Mediterranean hurricanes, are mesoscale cyclones with morphological and physical characteristics similar to tropical cyclones. Although less intense, smaller, and rarer than their Atlantic counterparts, medicanes are very hazardous events threatening islands and continental coasts within the Mediterranean Sea. The latest strong episode, Medicane Ianos (September 2020), resulted in severe damages in Greece and several casualties. This work investigates the oceanic response to these extreme events along the Mediterranean coasts under present‐day and future (late 21st century) climate conditions. To this end, a coupled hydrodynamic‐wave model is used to simulate both storm surges and wind‐waves generation and propagation in the Mediterranean Sea at high resolution (∼2 km) along the coastlines. A data set of thousands of medicanes synthetically generated from 20 global climate models and two atmospheric reanalyses is used to derive the atmospheric forcing fields. Regional coastal hazards assessment is performed for the present and future climates. For the first period, highest medicane‐induced waves are found in the central and the southwest part of the western Mediterranean, while greatest storm surges are found in the Adriatic Sea and regions characterized by wide and gently sloping continental shelves. Results obtained for future changes show amplitudes generally smaller than the associated uncertainty due to limited agreement among models (especially for coastal elevation). Though, model consensus is reached (60–75%) and relative intensity change is significant (10–20%) at some locations (e.g., 1 m increase of medicane‐induced significant wave height on average for south coasts of Sicilia).

Estimating population and urban areas at risk of coastal hazards, 1990–2015: how data choices matter

Abstract. The accurate estimation of population living in the low-elevation coastal zone (LECZ) – and at heightened risk from sea level rise – is critically important for policymakers and risk managers worldwide. This characterization of potential exposure depends on robust representations not only of coastal elevation and spatial population data but also of settlements along the urban–rural continuum. The empirical basis for LECZ estimation has improved considerably in the 13 years since it was first estimated that 10 % of the world's population – and an even greater share of the urban population – lived in the LECZ (McGranahan et al., 2007a). Those estimates were constrained in several ways, not only most notably by a single 10 m LECZ but also by a dichotomous urban–rural proxy and population from a single source. This paper updates those initial estimates with newer, improved inputs and provides a range of estimates, along with sensitivity analyses that reveal the importance of understanding the strengths and weaknesses of the underlying data. We estimate that between 750 million and nearly 1.1 billion persons globally, in 2015, live in the ≤ 10 m LECZ, with the variation depending on the elevation and population data sources used. The variations are considerably greater at more disaggregated levels, when finer elevation bands (e.g., the ≤ 5 m LECZ) or differing delineations between urban, quasi-urban and rural populations are considered. Despite these variations, there is general agreement that the LECZ is disproportionately home to urban dwellers and that the urban population in the LECZ has grown more than urban areas outside the LECZ since 1990. We describe the main results across these new elevation, population and urban-proxy data sources in order to guide future research and improvements to characterizing risk in low-elevation coastal zones (https://doi.org/10.7927/d1x1-d702, CIESIN and CIDR, 2021).

Assessing Vegetation, Nutrient Content and Soil Dynamics Along a Coastal Elevation Gradient in a Mississippi Estuary

Assessing Vegetation, Nutrient Content and Soil Dynamics Along a Coastal Elevation Gradient in a Mississippi Estuary

Interplay Between Coastal Elevation and Wave Height Controls the Occurrence of Coastal Boulder Deposits in the Aran Islands, Ireland

Coastal boulder deposits (CBD) are wave-emplaced supratidal accumulations that record extreme inundation on rocky coasts. They are poorly understood but are of growing importance as we seek to better understand the extremes of wave power on coastlines. The Aran Islands, Ireland, host CBD in varying settings ranging from sheer cliff tops to wide shore platforms, and at elevations to about 40 m above sea level. Deposits are known to be active during strong storm events and provide a unique opportunity to examine relationships between wave energy, setting, and CBD occurrence. We use topographic elevation (Z) and offshore 100-years significant wave height (Hs,100) to calculate a dimensionless elevation Z* = Z/Hs,100 at 25 m intervals all along the Atlantic-facing coasts of the Aran Islands, and record whether CBD were present or absent at each location. The data reveal universal CBD presence at locations with low dimensionless elevations and near-monotonic decreasing frequency of CBD occurrence as Z* increases. On the Aran Islands, CBD are restricted to locations with Z*&amp;lt;3.13. For high elevation deposits it appears that unresolved local factors may be the major determinants in whether CBD will form. This approach can be applied at any CBD-bearing coastline and has the potential to change the way that we think about these deposits. Evaluation of dimensionless elevations at CBD locations around the world will help build broader understanding of the impact local shoreline conditions have on CBD formation. Determining these relationships contributes to the ongoing need to better understand interactions between extreme waves and rocky coasts.

Analysis of the Makran Coastline of Iran’s Vulnerability to Global Sea-Level Rise

The SE coast of Iran is of great economic and environmental importance. Global climate change affects this coastline through sea level rise (SLR), compounded by a decrease in sediment budgets in coastal areas. This study developed a Coastal Vulnerability Index (CVI) for the SE coast of Iran using satellite, instrumental and field data. Eight risk variables were defined: coastal slope, regional coastal elevation, mean tidal range, mean significant wave height, rate of relative sea-level change, rate of shoreline change, environmental sensitivity and socio-economic sensitivity. The coast was divided into 27 segments based on geomorphic, environmental and socioeconomic traits. Coastal segments were categorized based on their vulnerability to each risk factor using a CVI. The resulting maps highlighted the vulnerability of each coastal segment to SLR. Approximately 50% of the coast is comprised of mostly rocky shores, which are less vulnerable to SLR. Approximately 33% of the coastal length, including sandy beaches, tidal flats and mangrove forests, were determined to be highly vulnerable to SLR. Approximately 12% of the coastline was determined to be moderately vulnerable. Population centers and infrastructure were ranked as highly-to-moderately vulnerable to SLR. This study highlighted the high vulnerability of low-lying areas, such as lagoons and mangroves, in the western part of the Iranian coast of Makran. Proper coastal management and mitigation plans are essential in the future to protect coastal societies and environments.