Beach Berm Research Articles

Permanent loss of barrier island resilience due to a critical transition in dune ecosystems

Barrier islands cover a large fraction of US coasts and support unique ecosystems and coastal infrastructure. The ‘barrier’ function of a barrier island depends on coastal dunes that can prevent storm flooding and widespread ecosystem loss. Furthermore, dune-less barriers are more susceptible to breaching and potential drowning under sea level rise. Here we study the transition from richly-vegetated barriers with mature dunes (‘high’ state) to dune-less barren barriers (‘barren’ state) using data from a representative set of barrier islands in Virginia, US. We find that these two states are possible stable solutions of a non-linear stochastic dynamics characterized by a tipping point at which barriers with elevation around beach berms experience a critical transition into a permanently barren state. Our results suggest that frequently-flooded dune-less barren islands are a natural endpoint of barrier’s evolution under sea level rise.

The Impact of Foreshore Slope on Cross-Shore Sediment Transport and Sandbar Formation in Beach Berm Nourishment

Foreshore slope is crucial in designing beach berm nourishment schemes and understanding coastal responses to wave forces. Beach berm nourishment often suffers from a high loss rate, necessitating theoretical research and design parameter comparison to mitigate these losses early on. This study uses Bagnold’s energy conservation method and the small-angle approximation method to establish a relationship between cross-shore sediment transport and foreshore slope. The feedback mechanism between these factors shows that when the foreshore slope is fewer than 10 degrees, a smaller initial slope results in a reduced rate of sediment transport. Over time, the foreshore slope decreases and eventually reaches equilibrium, promoting the formation of an offshore sandbar, which helps reduce sediment loss. Using data from Guanhu Beach in Dapeng Bay, this study constructs a realistic numerical beach model to simulate the dynamic behavior of beach profiles with varying foreshore slopes under the influence of monsoon waves and storm surges. The simulation results support the feedback mechanism findings, demonstrating that profiles with minimal foreshore slopes experience the least initial sediment loss, thus facilitating sandbar formation more effectively. These insights can inform beach berm nourishment strategies, emphasizing early-stage efforts to expand beach areas and reduce sediment loss.

The Feedback from a Beach Berm during Post-Storm Recovery and How to Improve the Berm’s Restorative Efficiency

The efficiency of beach recovery during a time of moderate waves following storm waves is closely related to the interaction between dynamics, sediment, and the landform. The existing studies mainly focus on the description of erosion and accretion characteristics, while the response and feedback mechanism of beach berm sediment have not been elucidated. The main controlling factors of recovery efficiency are not clear. In this paper, field observation and the XBeach numerical model are utilized on the sandy beach in Puqian Bay, China, to capture high-frequency cross-shore data during the post-storm recovery period. The variation characteristics and rules of berm elements, including berm ridge height and slope on two sides of the berm ridge, are analyzed. It is observed that the berm constantly changes to adapt to dynamic conditions. Additionally, a correlation between volume change and certain landform parameters is proposed, leading to the identification of a new relationship in wave run-up. The new forum reflects berm influence and considers the berm ridge and berm width.

An experimental study on the evolution of beach profiles under different beach nourishment methods

Due to the influence of storm surges, hard coastal protection structures may exacerbate beach erosion, hence beach nourishment methods are considered in coastal protection and restoration efforts. An experiment is conducted in a wave flume to compare the advantages and disadvantages of three types of beach nourishment methods (berm nourishment, profile nourishment, and bar nourishment) under non-storm and storm wave conditions. The experiment analyzes wave height distribution, beach morphology changes, net sediment transport, shoreline recession, beach width increase, and beach volume changes. The findings indicate that the implementation of bar nourishment strategies facilitates the pre-breaking of storm waves, thereby mitigating the disruption caused by wave breaking on water flow dynamics. Moreover, the application of berm and profile nourishment methods proves to be highly effective in expanding the width of the beach and bolstering its stability. However, it is worth noting that bar nourishment exhibits limited efficacy in terms of restoring beach berms and mitigating coastal erosion within the same duration of wave action. The study presents two equations incorporating hydrodynamic parameters to predict the erosion or accretion status of beaches, and compares the predicted results with experimental data, thereby refining the criteria and making the formulas more applicable to beach nourishment projects. These findings provide valuable insights into the strengths and weaknesses of different beach nourishment methods, which will contribute to the implementation of nourishment projects.

Experimental Analysis of the Changes in Coral Sand Beach Profiles under Regular Wave Conditions

This study utilized 50 laboratory experiments to document the evolution of coral beaches under varying regular wave conditions, including five distinct wave periods and ten wave heights. Both the type of equilibrium beach and the shape of sand bars were used to represent beach evolution. The evolution of coral sand beaches was then compared to quartz sand beaches. The experimental results show that the predicted (modeled) equilibrium profile of a quartz sand beach was not applicable to coral sand beaches. Compared to sand bars on quartz sand beaches, the distance from bar crests to the beach berm in coral sand beaches was greater, whereas the erosional depth of sand troughs was deeper. However, the grain size distribution of sand associated with the coral sand beach under wave action was consistent with Celikoglu’s law. Both an equilibrium beach profile classification model and a sand bar shape prediction model for coral sand beaches were developed based on the experimental data.

Morphodynamic Response of Open and Embayed Beaches to Winter Conditions: Two Case Studies from the North Atlantic Iberian Coast

The morphological responses of two mesotidal beaches located in different coastal settings (embayed and open sandy beaches) on the northwestern Iberian coast were monitored during the winter of 2018/19. The offshore wave time series analysis is related to high-resolution topo-bathymetric measurements to explore spatial-temporal morphological variability at monthly to seasonal scales. Both locations are subjected to the North Atlantic wave climate which exhibits a pronounced seasonality. Throughout the last decade (2010–2020), significant wave heights reached values of up to Hs~9 m during winters and up to Hs~6 m during summers. On average, approximately 12 storms occurred annually in this region. The results clearly reveal divergent morphological responses and sediment transport behaviors at the upper beach and the intertidal zone during the winter for each location. In the embayed beach (Patos), sediment transport in the nearshore is governed by cross-shore processes between the beach berm and a submerged sandbar. In contrast, the open beach (Mira) showed dynamic sediment exchanges and three-dimensional morphologies alternating between accumulation and erosion zones. Overall, both beaches exhibited an erosional trend after the winter, particularly concerning berm erosion and the subaerial beach volume/shoreline retreat. This study highlights the contrasting morphodynamic response on open and embayed beaches to winter conditions, integrating both the subaerial and submerged zones. Local geological and environmental factors, as well as the coastal management strategies applied, will influence how the beach responds to winter wave events. Monitoring and understanding these responses are essential for effective coastal management and adaptation to changing climate.

Zooplankton composition following an artificial mouth breaching event in Lake St Lucia, South Africa

Lake St Lucia is one of the most important estuarine systems in South Africa, but the long history of anthropogenic intervention has threatened its integrity. With the exception of sporadic overtopping events and periodic marine connectivity via the uMfolozi River, the St Lucia Estuary remained closed off from the Indian Ocean since 2007. Due to the build-up of sediment and prolonged mouth closure, the beach berm was artificially breached in January 2021, fully reconnecting St Lucia to the Indian Ocean for the first time in 13 years. This study aimed to determine the effect of this breaching event on St Lucia’s zooplankton community by analysing samples from March, May and August 2021, at five representative sites throughout the lake system. The mouth remained open for only five months, and the system was still largely oligo- to meso-haline due to high freshwater input. The patterns in the zooplankton were related more to the prevailing environmental conditions than to the breaching event itself. The composition of zooplankton in the system did change; however, the presence of marine taxa was not far-reaching nor long-lasting, most likely due to the limited tidal intrusion, strong outflow and predominant salinity regime.

Microtextures on quartz grain surfaces in the Bay of Bengal shoreline sediments, Bangladesh: Implications for sediment transport process and depositional environment

SEM and SEM-EDS studies of quartz grains in the shoreline sediments of the Bay of Bengal, Bangladesh were carried out to evaluate the mode of origin, paleoclimate, and depositional environment. A total of 38 microtexture types were identified, which were grouped into mechanical (23 features), mechanical/chemical (6 features), and chemical (9 features) origins. The morphology of quartz grains in the shorelines was dominantly sub-angular to sub-rounded in shape, which represents robust energy conditions, short residence time, low weathering, and nearby sediment provenance. The microtextures of mechanical origin such as straight and curved scratches, pits, broken edges, and crescent-shaped features were relatively abundant in the eastern site samples (Section-I) indicating high-energy, fluvial, and beach environments. The abundance of V-shaped marks and smooth surfaces of quartz grains indicate high-velocity storm conditions and/or high-energy impact events. The well-rounded outline, low relief with dish-shaped depressions, mechanically upturned plates, and arcuate steps were also observed on quartz grain surfaces. These features suggest that they were developed during an aeolian process in the beach berm environment. Etching, solution/irregular pits, and differential relief on quartz grains were somewhat elevated in the western site samples (Section-III), reflecting that these microtextures were associated with a subaqueous collision and humid climates in the fluvial and nearshore environments. Quartz grains in all sections represented microtextures of high energetic subaqueous environment as well as wind events. However, the absence of corrosion channels and high density of voids in the quartz grains revealed low degree of weathering.

REVEALING THE GEOMORPHOLOGIC IMPACTS OF HURRICANE IAN IN SOUTHWEST FLORIDA USING GEOSPATIAL TECHNOLOGY

Abstract. Geospatial data were used to analyze changes to geomorphology of barrier islands and beaches in Southwest Florida resulting from Hurricane Ian in late September 2022. The hurricane generated high intensity winds and storm surge causing more than $112 billion in damages, along with massive sediment mobilization due to erosion and deposition. This study quantified net sediment loss and gain on specific barrier islands by storm surge (Sanibel, Naples, Fort Myers Beach, others, though this paper focuses exclusively on Sanibel) by comparing pre- and post-Ian topography generated by a drone-flown LiDAR sensor; changes in elevation were used to quantify spatial variation in sediment volume. Data were collected immediately after Hurricane Ian and compared against topographic data collected by NOAA in 2018. Digital elevation models (DEMs) were used to compare topography, shoreline positions (relative to Mean High Water), foredune position, and volumetric changes using GIS technology. In general, the shoreline position after Ian changed little, indicating that the incoming surge had little influence on the beach. The foredunes, however, were deflated and set back by surge overwash. The outgoing surge created a much more dramatic geomorphologic change. Erosional surge channels cut through the foredunes and upper beach berm along many regions of the coastline. The ebb erosion also caused extensive damage to physical structures when located immediately behind the foredune. Lastly, this work demonstrates the value of employing GIS and remote sensing technology to problems of beach and dune management, the restoration of coastal ecosystems, the enhancement of resilience capacity of both natural and developed infrastructure, and the development of new policy needed to contend with the effects of climate change.

A PROCESS-BASED NUMERICAL MODEL OF SHOREFACE PROFILE EVOLUTION

It remains a challenge to model numerically profile evolution across the shore-face from deep water to the shoreline with stability and accuracy. At long time scales, attempts to date typically utilise equilibrium profile shapes or bed slopes, with profile change based on the degree of disequilibrium and wave/current forcing, primarily for the surf zone in erosion events. Simulation of shoreward bar migration and beach recovery after erosion events is generally poor. Here we present an effective integrated framework and process-based dynamics in the form of a new software package that successfully models the whole shore-face zone seamlessly from relative deep water to the beach. It incorporates analytical procedures, including some simplified empirical relationships, that describe the forcing of waves and currents and the sedimentation responses that change the profile. It is shown to simulate profile evolution satisfactorily, with shoreward as well as seaward sand transport, bar development and migration and beach erosion and accretion, in a manner and at time-scales consistent with measured data, for both small scale laboratory and prototype modal and storm conditions. The model caters for water level variations due to tide, storm surge and/or sea level rise. It may be used to assess beach nourishment deposition at the beach berm, lower shore-face or across the surf zone.

OBSERVATIONS AND MODELING OF EROSION AND RECOVERY OF A COUPLED BEACH-DUNE SYSTEM

The geomorphic and ecological vulnerability of barrier islands is influenced by the way they respond to oceanographic and anthropogenic forcing over a broad range of temporal scales. Integrated models capable of simulating these processes are increasingly necessary to understand barrier island trajectories under future conditions and to aid in management decisions by evaluating the impact of potential restoration activities. While there are numerical models capable of simulating some of the dominant barrier processes, the role of beach berm evolution is rarely included despite the important function of berms in sustaining beaches, enabling dune growth via Aeolian transport, and mitigating backshore and dune erosion during storm events. This is primarily due to a lack of available data that resolves details of beach profile evolution at necessary temporal scales (e.g., seasonal, post-storm recovery, etc.) to test and develop models and the inherent difficulty of including these intra-annual processes into decadal scale models of barrier island evolution. Here we describe a unique and growing dataset of environmental forcing and barrier island topographic change. We also use the dataset to develop and test a model for barrier island evolution and quantify the role of storms, moderate wave conditions, and wind-driven transport in dictating coastal change on various timescales.

CORPUS CHRISTI SHIP CHANNEL DEEPENING PROJECT: OVERVIEW and MODELING APPROACH TO ASSESS ENVIRONMENTAL IMPACTS

The Corpus Christi Ship Channel in Texas connects the Port of Corpus Christi to the Gulf of Mexico. The Port is seeking to deepen the Corpus Christi Ship Channel to 22.9m (75ft) nominal depth in order to allow fully loaded very large crude carriers (VLCC’s) to access proposed terminals within the port complex. As a part of the environmental coordination requirements of the National Environmental Policy Act (NEPA) the Port Authority prepared a number of studies to assess the potential environmental impacts of the proposed channel deepening. These included assessing changes in hydrodynamics, salinity, storm surge, and sedimentation patterns including sediment movement generated by vessel generated currents. The channel design was also verified through vessel maneuvering studies which were conducted using modeled currents, dynamic underkeel clearance assessment, and propeller scour potential determination. The fate of proposed beneficial use of dredged materials to construct a submerged beach berm and perform beach nourishment was also assessed.

Grain size distribution of modern beach sediments in Sri Lanka

Grain size distributions are widely used to describe sedimentary geochemistry, depositional environment, and sediment transportation. The objective of this study is to analyze grain size distributions of modern sandy beach sediments in Sri Lanka. Sediment samples (n = 90) were collected from beach berm, representing the entire coastline of Sri Lanka. Grain sizes were determined by the dry-sieving method. Statistical parameters such as mean size, sorting, skewness, and kurtosis were calculated using GRADISTATV9.1 software for all the sieved sediment samples. Grain size variations (108.2 – 609.8 µm) show that Sri Lanka mainly consists of medium sand, whereas the northeast part of the country mixes with fine sand due to the influence of Bengal fan sediments. The variations of skewness (-0.229 – 0.446) and sorting (1.305 – 2.436) indicate symmetrical distributed moderately sorted samples. These variations specify a moderate energy depositional environment/wave action around the coastline of Sri Lanka. In addition, grain size analysis confirmed relatively high and low energy deposition environments on the west and east coasts, respectively. Accordingly, the west coast is more vulnerable to coastal erosion compared to the east coast of Sri Lanka. Therefore, this study provides the baseline grain size distribution data that can be used in decision-making for coastal zone management by mitigating beach erosion.

Influence of Beach Erosion during Wave Action in Designed Artificial Sandy Beach Using XBeach Model: Profiles and Shoreline

Beach width is an important factor for tourists’ comfort, and the backshore is a swash zone where sediment moves quickly. Artificial sandy beaches focus on beach width stability and evolution. This paper is based on an artificial beach project in Haikou Bay, where, in view of the existing conditions, a new type of beach profile that can protect beach berm and width without being eroded by large wave action. Numerical simulation based on XBeach model were conducted to predict the morphodynamical responses of the beach, including a diagnosis of the erosion spots under storm and normal wave events, respectively. Sediment fluxes along and across the shoreline under varied scenarios, dependent on profile width and backshore slope, were discussed. It was found that normal waves with lower heights and longer periods can induce stronger erosion than storm waves due to the landform of the inner-bay in Haikou Bay. Engineering and biological methods to reduce beach erosion during wave action were discussed. Biological methods such as green-plants-root-system can retain berm surface sediment without allowing it to be transported offshore by wave action. The design concept of this artificial beach project may inspire more beach design and protection projects in coastal zones.

Assessing the Coastal Vulnerability by Combining Field Surveys and the Analytical Potential of CoastSat in a Highly Impacted Tourist Destination

Tropical sandy beaches provide essential ecosystem services and support many local economies. In recent times, however, there has been a massive infrastructure expansion in popular tourist destinations worldwide. To investigate the shoreline variability at a popular tourist destination in Mexico, we used the novel semi-automatic CoastSat program (1980 to 2020) and the climate dataset ERA5 (wave energy and direction). We also measured the beach cross-shore distance and the foredune height with topographic surveys. The results indicate that the section of real estate seafront infrastructure in the study site presents a considerable shoreline erosion due to the fragmentation between the foredune ridge and the beach berm, based on the in situ transects. Moreover, foredune corridors with cross-shore distances of up to 70 to 90 m and dune heights of 8 m, can be seen in the short unobstructed passages between buildings. In the south section we found the coastline in a much more stable condition because this area has not had coastal infrastructures, as of yet. For the most part, the remote sensing analysis indicates constant erosion since 1990 in the real estate section (mainly seafront hotels) and an overall accretion pattern at the unobstructed beach-dune locations. This study demonstrates the catastrophic consequences of beach fragmentation due to unplanned real estate developments, by combining in situ surveys and a freely available big-data approach (CoastSat).

Successful Coastal Protection by Step Concrete Revetments in Thailand

Coastal revetment has a main function to protect eroding shorelines. Sometimes, the revetment is considered ineffective and harmful to the environment. This article presents 3 case studies in Thailand where stepped concrete revetments were successfully implemented. If theoretically accurately designed, the revetments will not only protect the coastlines but also enhance community’s well-being. The case studies at the Suan-Son beach, the Pra-Ae beach, and the Laem-Sadet beach advocate such a claim. When the incoming waves break on the steps, the revetment crest is accurately configured, the front slope is well-designed, the wave reflection will be minimized. The sand will climb and deposit on the steps. The beach berm will be wide. People can walk either on the beach or the revetment crest. Tourism will be promoted. Livelihoods of coastal communities will be enhanced. Sustainable coastal development can follow. None of these can happen if the coast is still being eroded. The revetment is not a bad thing. What is bad is an engineer who poorly designs the revetment. The misleading belief that the revetment will do more harm than good must be adjusted.

Natural and nature based features for environmental enhancement and coastal storm risk management: a case study on Marco Island, Florida, United States

Natural and Nature-Based systems provide an opportunity for adaptive response to Coastal Storm Risk Management and Sea Level Rise. The Tigertail Lagoon/Sand Dollar Island Restoration on Marco Island, Florida, presents a case study designed to maintain and enhance an existing coastal barrier system consisting of a 3-km-long sand spit and tidal lagoon ecosystem that is otherwise evolving toward closure. The case study is part of a nature-based adaptive management plan to restore and stabilize the sandspit and tidal lagoon through cyclic use of sediment within the system. This approach seeks to preserve existing protective habitats and landforms that also serve as natural coastal barriers to protect upland development. Design of the restoration plan considers the functions of a wildlife nature preserve and evolution of complex tidal inlet morphologic features bordered by a heavily developed barrier Island. The design aims to restore and enhance a sandspit degraded by a sequence of storms since Major Hurricane Irma impacted Southwest Florida in 2017 and improve the existing deteriorated habitat by enhancing tidal exchange through restoration of the lagoon flow channel. Total wetland area will be increased by relocating the sand spit seaward of its present location to where it was located in approximately 2017. The reconstructed beach berm will provide enhanced resiliency to high frequency weather events. Sediment will be sourced from the existing sand spit and an innovative sand trap that will maintain the lagoon entrance open while providing beneficial re-use for excess sediment that continues to accumulate at the end of the spit. Components of the project were analyzed using existing engineering models and methods such as the Coastal Modeling System (CMS) and XBeach. Enhancing and preserving this barrier island feature and productive ecosystem provides an example of the enhanced coastal resiliency provided by natural and nature-based systems that are adaptable and responsive to sea level rise and ongoing coastal processes.

Reply to the comment by Dougherty, A.J. on “Relative sea-level records preserved in Holocene beach-ridge strandplains – An example from tropical northeastern Australia” by Brooke, B.P., Huang, Z., Nicholas, W.A., Oliver, T.S.N., Tamura, T., Woodroffe, C.D., Nichol, S.L.

The approach and results of our 2019 paper (Brooke et al., 2019) have been criticised by Dougherty (2022). We examined the sensitivity of a tropical, coarse sand strandplain to changes in relative sea level as expressed through beach-ridge morphology and the elevation of beach berms preserved in the succession of cyclone-generated beach ridges at Cowley Beach, Queensland, Australia. Rather than presenting a new sea-level curve for this region as suggested by Dougherty, our 2019 study of the Cowley Beach strandplain revealed that when compared with the modelled Holocene relative sea-level record and sea-level indicator data for north-eastern Queensland, the strandplain morphology and stratigraphy provide a first-order representation of sea-level position. Importantly, Dougherty (2022) has overlooked the processes involved in the formation of beach ridges at this site and the spatial coverage of our analysis of the strandplain morphology. Both these factors are fundamental to the approach and conclusions of our 2019 paper. We reiterate here that the Cowley Beach strandplain morphology and succession of beach-berm deposits have elevation patterns that match well the broad trend in the regional relative sea-level model for the past 7 ka. We highlight those key beach-ridge formative processes and data limitations neglected in the Dougherty Comment. Finally, we note the challenges and opportunities for further research into the sedimentary records preserved in this distinctive type of tropical strandplain.

Influences of beach berm height on beach response to storms: A numerical study

The field observation at two neighboring beaches showed significant effects of berm height on beach profile changes during a major storm. The fully nonlinear Boussinesq wave model, FUNWAVE-TVD, with a sediment transport module was used to simulate the beach erosion processes of the two beaches. The model reproduced the beach profile changes in good agreement with the measured data. The model results revealed that, for the beach with a higher berm, the wave force, wave-induced undertow flow, along with the higher sediment concentration on the berm induce more offshore sediment transport and cause significant beach profile changes compared to the beach with a lower berm. The erosion trend with different berm heights was predicted by using a series of numerical tests with different berm heights and offshore forcing conditions. The test results suggested that beach erosion increases with the berm height until the berm height reaches a certain level.

Simulation Study of Scarp and Berm Formation Using a Suspended Sediment Transport Model

Vu, X.H. and Lee, J.L., 2021. Simulation study of scarp and berm formation using a suspended sediment transport model. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 504–508. Coconut Creek (Florida), ISSN 0749-0208. Beach berms and scarps are common morphological features that develop repetitively due to the cyclic incidence of mild and storm waves. However, beach scarp and berm formations, as well as their morphodynamics, have not been researched thoroughly. In particular, scarp generation is often observed at nourished beaches or under the incidence of oblique storm waves; scarps can pose severe risks to beach users and negatively impact local ecosystems. A numerical study was conducted using a suspended sediment transport model developed in a previous study to quantify the morphodynamic responses of beach berms and scarps to the foreshore region as well as offshore sand motion. In the present study, the destructive beach slope at the foreshore was controlled using Kim's empirical formula on the foreshore slope.