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Coral reefs protect coastlines from inundation and flooding and serve over 200 million people globally. Wave transformation has previously been studied on coral reef flats with limited focus on forereef zones where wave transformation is greatest during high‐energy conditions. This study investigates the role of forereef spur and groove (SaG) morphology in wave energy dissipation and transmission at the reef crest. Using XBeach on LiDAR‐derived bathymetry from One Tree Island in the southern Great Barrier Reef, we reproduced dissipation rates comparable to SaG field studies. We examined how wave energy dissipation differs between realistic bathymetry and those with SaG features removed, demonstrating an up to 40% decrease in dissipation when SaG features are absent. We then investigated changes to wave energy dissipation and wave transmission at the reef crest based on IPCC AR5 emission scenarios (RCP2.6 and RCP8.5) and a total disaster scenario (TD) for the year 2100. For RCP2.6, an increase in wave heights of 0.8 m and an increase in water level of 0.3 m resulted in a two‐fold increase in dissipation rates. For RCP8.5 and TD, with no increase in incident wave height, dissipation rates were 29% and 395% lower than RCP2.6. This resulted in increased wave transmission at the reef crest by 1.8 and 2.7 m for the RCP8.5‐ and TD based models, respectively, when compared to the RCP2.6‐based model. The results from our novel modeling approach of using long‐shore varying accurate bathymetry on forereefs show increased wave energy dissipation rates with implications for reducing coastal flooding and island inundation on reef‐lined coasts. Plain Language Summary: Coral reefs protect coastlines from floods and waves, benefiting over 200 million people globally. We studied how waves change over coral reefs, focusing on the forereef zone where wave transformation is most significant during high‐energy conditions. The shape of the forereef, specifically the long comb‐like grooves that cut through coral reefs, known as spur and grooves (SaG), modify wave energy transformation. Utilizing digital representation of waves over accurate reef shapes (known at bathymetry), we simulated wave dissipation rates comparable to real‐world SaG studies. By comparing high resolution, accurate bathymetry to smoothed bathymetry with SaG removed, we demonstrate a 40% decrease in wave energy dissipation. Next, we investigated how wave energy dissipation changes in different forereef environments. We considered low and high emission scenarios (RCP2.6 and RCP8.5) from the IPCC AR5 report and a total disaster scenario (TD) for the year 2100, considering changes to wave power, and water‐level. We found that models based on high‐emission scenarios (RCP 8.5) had decreased dissipation rates, resulting in more water passing the reef crest. Our study highlights the benefits of using accurate reef shapes in simulating wave energy dissipation on coral reefs. Accurate bathymetry can incorporate features such as SaG of different shapes, which increase wave dissipation. Key Points: Accurate bathymetry (<1 m) in forereef wave energy dissipation models can include features such as spurs and grooves (SaG)SaG increases forereef wave energy dissipation when compared to similar bathymetry without SaGForereef dissipation shifts from bed friction to wave breaking in modeled environmental conditions based on future climate projections [ABSTRACT FROM AUTHOR]

The Great Barrier Reef (GBR) is the largest coral reef system on earth, with ecological and scientific importance for the world and economic and iconic value for Australia. However, the characterisation of its offshore wave climate remains challenging because of its remoteness and large dimensions. Here, we present a detailed analysis of the offshore wave climate of the GBR, unveiling the details of both modal conditions and extreme events. We used a calibrated satellite radar altimeter dataset (spanning from 1985 to 2018) to quantify wave climate, assess the influence of climate drivers, and analyse the wave conditions generated by tropical cyclones at three main regions of the GBR (northern, central, and southern). Our results indicate average significant wave heights of 1.6 m, 1.5 m, and 1.7 m for the northern, central, and southern GBR, respectively. The modal wave climate exhibits substantial seasonality, particularly in the northern region with dry season wave heights up to twofold larger than during wet season. The northern and central wave climates show decreasing wave height and wave energy trends over the last 33 yrs, whilst the southern region remains stable. Consistent with prior studies, we found that the wave climate in the southern region is modulated by the El Niño-Southern Oscillation and the southern annular mode, with influence additionally extending to the central region. Analysis of the extreme waves generated by tropical cyclones revealed they generate large, long period waves, frequently above 7 m, resulting in wave power up to 32-fold higher than median conditions. [ABSTRACT FROM AUTHOR]

The wave fields of coastal bays are comprised of waves generated by far-off storms that enter the bay to combine with waves generated locally by winds inside the bay and regionally outside the bay. In any given location, the resultant wave field varies spatially and temporally, and affects coastal features, such as beaches in estuaries and bays (BEBs). However, wave fields in enclosed bays with tidal shoals are poorly studied, limiting the efficacy of coastal protection and restoration projects in these systems, a critical focus in light of ongoing sea level rise. Here we present observations of the wave field in Tomales Bay, a 20-km-long, narrow, semi-enclosed embayment on the wave-dominated coast of Northern California (USA) with a spring-tide range of 2.5 m. We deployed pressure sensors near several beaches along the linear axis of the bay. Low-frequency waves ( 4 ∗ 10 - 2 - 2.5 ∗ 10 - 1 Hz or 4–25-s period) were not observed further than 4 km of the mouth, delineating the "outer bay" region, where remotely generated swell and regionally generated wind waves could dominate. The wave spectrum of the landward "inner bay" was dominated by fetch-limited waves generated within the bay with frequency ≥ 2.5 ∗ 10 - 1 Hz. The energy of both ocean waves and locally generated wind waves across all sites were controlled by the tide, but the former by changes in attenuation and the latter likely by modulation of wave generation. Wave energies were low at low tide and high at high tide, but high-frequency wind wave energy was increased during ebb tides while lower-frequency swell energy was reduced during ebb tides, suggesting different mechanisms of tidal influences. Thus, in addition to fluctuations in winds and the presence of ocean waves, tides exert a strong control on the wave energy spectra at coastal features in mesotidal regions. In general, events that may be impactful for BEB morphology are expected to occur when waves due to high winds or high-swell event arrive during high-tide periods. However, no such events were observed during our study and questions remain as to how rarely such events occur across the bay. [ABSTRACT FROM AUTHOR]

Women face disproportionate challenges while undertaking coastal fieldwork. We draw on 18 responses that specifically raise fieldwork issues from an international survey about perceptions and experiences of gender inequality for those working in coastal sciences to discuss two common themes. These themes are barriers to fieldwork participation and challenges for women working in coastal field settings such as boats or working on beaches, including discrimination and sexual harassment. We suggest five priority behavioural and policy changes to improve the fieldwork experience for women in coastal sciences: (i) publicise field role models and trail blazers, (ii) improve opportunities and capacity for women to undertake fieldwork, (iii) establish field codes of conduct, (iv) acknowledge the challenges women face in the field and provide support where possible, and (v) foster an enjoyable and supportive fieldwork culture. [ABSTRACT FROM AUTHOR]

Habitat interactions play key roles in regulating biodiversity and ecosystem functions. This is particularly important in aquatic ecosystems, where the flow of water facilitates exchanges of energy and matter. Oyster reefs, a highly degraded habitat globally and a key focus for restoration efforts, can reduce water movement and facilitate the deposition of particles around them, affecting nutrient cycling in surrounding sediments. The effects of these reefs on sediment infauna taxonomic and functional biodiversity, however, remain unknown. We sampled sediments at increasing distances from reefs at three estuaries to evaluate the relationships between proximity to oyster reefs and composition and functionality of infaunal communities and explored the potential mechanisms behind those relationships. Sediments close to oyster reefs had consistently greater amounts of labile organic matter, which in turn was positively related to the number of taxa and total abundance of infauna. Also, the functional traits of infauna, such as bioturbation and feeding modes, were related to proximity to reefs, but they were variable between estuaries indicating the importance of background estuarine environmental conditions. These results suggest that habitat linkages between oyster reefs and sediments are important in regulating taxonomic biodiversity, while functional biodiversity seems to be driven by processes operating at larger scales. Given burgeoning restoration initiatives worldwide, particularly those of oyster reefs, incorporating seascape interactions can help inform recovery of biodiversity and functions beyond the target habitat at the seascape level, which is often overlooked. [ABSTRACT FROM AUTHOR]

Many estuaries contain sandy beaches that provide habitats and offer protective buffers for wetlands and infrastructure, alongside cultural and recreational resources. Research underpinning coastal management tends to focus on tide‐ and swell‐dominated sandy beaches, but little attention is given to beaches in estuaries and bays (BEBs) that exist along a continuum of wind/swell wave, tide and riverine influence. BEBs are subject to less wave energy than open coast locations because of the generally narrow window of directions for which ocean waves can propagate through the entrance. However, when storm wave direction coincides with the orientation of the estuary or bay entrance, waves can penetrate several kilometres inside. Here we focus on eight BEBs in two major bays/estuaries in Sydney, Australia and present observations from before and after a major extratropical storm with waves from an atypical direction in June 2016. We quantify magnitudes of beach erosion and recovery rates for 3 years post‐storm. We show that when high‐energy storm waves penetrate bays and estuaries, BEBs can undergo up to 100% of subaerial beach erosion. Three years after the storm, only 5 of the 29 (17%) eroded subaerial beach profiles had recovered to their pre‐storm volume. This is likely due to the lack of low‐frequency, beach‐building waves at BEBs under modal weather conditions in between storms, in contrast to open coast beaches. We also show that the recovery of BEBs may be limited by the absence of adjacent sediment reservoirs due to the dominance of tidal processes mid‐channel. Our study highlights the unique behaviour of BEBs relative to beaches on the open coast, and that shifting wave direction needs to be considered in long‐term beach resilience under climate change. © 2020 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Sediment transport calculations are used globally in the numerical models that coastal managers, scientists and engineers use to assess and forecast coastal change. Most of the existing sediment transport equations were defined based on experimental results using siliciclastic sands. Yet these equations are applied to all types of sand, including carbonate sands that have different characteristics and therefore, settling behaviour. A rigorous management of the transport of carbonate sand is essential for the present and future management of sedimentary features in coral reefs such as sandy beaches or reef islands. Here we present a new approach to estimating the drag coefficient of carbonate sands that considers both friction and pressure. Based on our new method, the calculated drag coefficients explain the great variability in settling velocities of carbonate sand observed in nature (from 0.025 m/s to 0.364 m/s in our database). Using our formula, we demonstrate that even small differences in the settling velocity obtained with the new drag coefficient can lead to substantial changes in sediment transport and call for an update of numerical models. [ABSTRACT FROM AUTHOR]

Wave and tide induced sediment transport pathways and rates govern the morphological evolution of estuarine systems. An understanding of the morphodynamics of these systems is required to maintain their commercial, biological and recreational value. The morphodynamics of Port Stephens estuary, a micro-tidal estuary located on a wave dominated southeast coast of Australia were investigated using bathymetric surveys and current velocity data from several locations over the estuary. This provided detailed insight into the rates and direction of movement for the main sedimentary features of the system, and how these features interact with the processes that drive their evolution. We used these findings to develop a conceptual model for estuarine morphodynamics that accounts for fair weather and storm conditions. Our model explains how sediment eroded from the estuarine beaches is trapped by the adjacent flood-tide delta. The model is applicable to fetch-limited estuaries that do not have offshore sources of sediment, where the tidal currents are weak in relation to the incident ocean waves, and that have a wide, stable entrance through which ocean waves can propagate into the estuary. The model is multi-scale in that it encapsulates both short-term and local process, and large scale evolution of an estuary; therefore, it represents a tool that may be used in developing sustainable estuary management strategies. [ABSTRACT FROM AUTHOR]

Fellowes, T.E.; Gacutan, J.; Harris, D.L.; Vila-Concejo, A.; Webster, J.M., and Byrne, M., 2017. Patterns of sediment transport using foraminifera tracers across sand aprons on the Great Barrier Reef. Sediment dynamics exert large control over coral reef geomorphological evolution and are vital to understanding past and present geomorphic responses. Large benthic foraminifera (LBF) live in the algal reef flats, and their tests (shells) are transported post-mortem by waves and currents onto back-reef environments, including sand aprons. This study investigated the patterns of transport linking surficial and downcore sediments in samples from three sand aprons with different wave exposures at One Tree Reef on the southern Great Barrier Reef (Australia). Six LBF genera represented up to 32% of the sediments analysed. Lagoonward transport increased LBF test abrasion and sediment bulk density. Sediment grain size and LBF abundance in sediments also decreased with lagoonward transport. Sediment transport patterns indicated by LBF species used as tracer were consistent with the prominent E-SE wave environment. A novel taphofacies approach was used to describe stratigraphic layers in downcore sediments based on LBF test abrasion and abundance. Varied sediment deposition rates did not affect the LBF test abrasion signature downcore. It appears that Baculogypsina sphaerulata has been the dominant species for at least 3 ka. Tests that were deposited slowly exhibited less or the same levels of abrasion than those that were rapidly deposited. It appears that test abrasion is primarily determined by the distance travelled rather than the influence of increased age or chemical dissolution. [ABSTRACT FROM AUTHOR]

Some of the most profound effects of climate change on ecological communities are due to alterations in species interactions rather than direct physiological effects of changing environmental conditions. Empirical evidence of historical changes in species interactions within climate-impacted communities is, however, rare and difficult to obtain. Here, we demonstrate the recent disappearance of key habitat-forming kelp forests from a warming tropical--temperate transition zone in eastern Australia. Using a 10-y video dataset encompassing a 0.6 °C warming period, we show how herbivory increased as kelp gradually declined and then disappeared. Concurrently, fish communities from sites where kelp was originally abundant but subsequently disappeared became increasingly dominated by tropical herbivores. Feeding assays identified two key tropical/ subtropical herbivores that consumed transplanted kelp within hours at these sites. There was also a distinct increase in the abundance of fishes that consume epilithic algae, and much higher bite rates by this group at sites without kelp, suggesting a key role for these fishes in maintaining reefs in kelp-free states by removing kelp recruits. Changes in kelp abundance showed no direct relationship to seawater temperatures over the decade and were also unrelated to other measured abiotic factors (nutrients and storms). Our results show that warming-mediated increases in fish herbivory pose a significant threat to kelp-dominated ecosystems in Australia and, potentially, globally. [ABSTRACT FROM AUTHOR]

Linking surficial sediment patterns in reef environments to the processes that underlie their depositional dynamics enables predictions to be made of how environmental changes will influence reef-associated sedimentary landforms, such as islands and beaches. Geomorphic linkages between sediment deposition patterns and the biophysical processes that drive them are often poorly resolved, particularly at broad landscape scales where tangible statements can be made about structural changes to landforms. The present study applies geospatial techniques to link patterns in reef sediment dynamics at Lady Musgrave Island to the underlying processes driving them. In situ calcification is characterized by developing a high resolution map of the surficial calcium carbonate producing communities inhabiting the reef platform, and associated sediments across the reef flat are analysed for grain size, kurtosis, sorting and threshold bed shear stress to explore transport pathways across the reef flat and lagoon. Wave energy is modelled across the entire reef platform as a potential driver of sediment dynamics, and morphometric linkages are empirically defined between wave energy and grain size. Findings indicate that carbonate sediments are primarily sourced from calcifying communities colonizing the outer periphery of the reef platform and that sediment grain size can be reliably linked to wave energy by virtue of a linear model. [ABSTRACT FROM AUTHOR]

Harbours are a focus of intensive and diverse activities and thus have a high potential to become centres of conflict between users. Reviewing the multiple uses associated with harbours provides important insights into maritime communities and the management of conflict. In this paper, seven international, multi-disciplinary groups provide their expert synthesis of individual harbours. After a detailed discussion experts from Sydney, Qingdao, Vigo, Auckland, Jakarta, Crete and Plymouth synthesised and shared their harbour's characteristics, user conflicts and how such conflicts have been researched and managed. The paper addresses an omission of 'conflict' in most of the research literature about harbours, and ports and scopes a research agenda that includes integration, risk appreciation and other approaches to these increasingly contentious maritime environments. This process provided an opportunity for global researchers to share the ways harbour conflicts are mitigated and the kinds of adaptations that are possible. [ABSTRACT FROM AUTHOR]

Trindade, W.; Pereira, L.C.C., and Vila-Concejo, A., 2016. Tidal modulation of moderate wave energy on a sandy tidal flat on the macrotidal Amazon littoral. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 487-491. Coconut Creek (Florida), ISSN 0749-0208. The present study focusses on the Vila dos Pescadores, a tidal flat located at the mouth of the Caeté estuary in the northeast of the Brazilian state of Pará. The aim was to establish the interactions amongst climatological and hydrodynamic processes, as well as fluvial dischages under different conditions. Eight campaigns were undertaken between June 2012 and April 2014. Results show that during the dry season, winds were moderate to strong and blew mainly from the northeast, coinciding with migration of the Intertropical Convergence Zone (ITCZ) to the northern hemisphere. During the rainy season, when the ITCZ was moving through this Amazon sector, winds blew from different directions at varying speeds. Maximum local Hs values were recorded during the dry season, when wind speeds were stronger and the waves came from θ < 70°N. During this period, Hs values ranged from 0.0 m (low tide) to 1.3 m (high tide), associated with periods between 2-7 s. During low tides, the waves break on the sandbanks but as the tide elevation exceeds ∼1 m, the waves start to propagate over the sandbank and towards the shoreline. Precipitation levels also had a strong influence on this tidal flat, especially during the first half of the year, when increasing precipitation provoked a surge in the discharge of the Caeté River (with lower Hs values). Under different conditions of hydrodynamic energy (monthly and seasonal variation, neap and spring tides, equinox and solstice periods), wave energy was correlated strongly with the tidal elevation. [ABSTRACT FROM AUTHOR]

The response of platform reefs to sea-level stabilization over the past 6 ka is well established for the Great Barrier Reef (GBR), with reefs typically accreting laterally from windward to leeward. However, these observations are based on few cores spread across reef zones and may not accurately reflect a reef's true accretional response to the Holocene stillstand. We present a new record of reef accretion based on 49 U/Th ages from Heron and One Tree reefs in conjunction with re-analyzed data from 14 reefs across the GBR. We demonstrate that hydrodynamic energy is the main driver of accretional direction; exposed reefs accreted primarily lagoon-ward while protected reefs accreted seawards, contrary to the traditional growth model in the GBR. Lateral accretion rates varied from 86.3 m/ka–42.4 m/ka on the exposed One Tree windward reef and 68.35 m/ka–15.7 m/ka on the protected leeward Heron reef, suggesting that wind/wave energy is not a dominant control on lateral accretion rates. This represents the most comprehensive statement of lateral accretion direction and rates from the mid-outer platform reefs of the GBR, confirming great variability in reef flat growth both within and between reef margins over the last 6 ka, and highlighting the need for closely-spaced transects. [ABSTRACT FROM AUTHOR]

Beach morphology, waves, tides, and current speeds were measured in a moderate-energy macrotidal environment of the Amazon coast (Atalaia beach, Brazil). The study was based on two complementary sets of data: (i) hydrodynamic and topographic data collected in four 25-hour campaigns during equinoctial and non-equinoctial periods, and (ii) climatological data (wind speed and direction, and rainfall) obtained from the Brazilian Institute of Meteorology. The results indicate that tidal currents run predominantly to the northwest during the flood tide and southeast during the ebb. The highest current speeds were recorded during the equinoctial period, reaching a maximum of 0.5 m/s in the flood tide. In March and June (rainiest months), ebb tide currents reached a maximum speed of 0.4 m/s. The tidal cycle was weakly asymmetric with the ebb tide lasting up to 6 hours and 40 minutes. High tides ranged from 4 m (nonequinoctial) to 5.7 m (equinoctial). Wave energy was modulated slightly during the low tide due to wave attenuation on the sandbanks, but substantial changes were not observed during ebb and flood tides. Modal wave height (Hb) varied from 1.1 to 1.43 m, associated with wave periods of 5.0-7.5s, with the highest values being recorded in November (intense winds). This beach can be classified as tide-modified, presenting primarily dissipative (O > 5) characteristic. Wave-dominated characteristics were observed in November, when Hs values were around 1.5 m and tidal elevation was approximately 4 m (non-equinoctial period). [ABSTRACT FROM AUTHOR]

Spur and groove features occur on the seaward reef slope of coral reefs around the world. They are believed to act as important natural breakwaters, regulating the hydrodynamic energy and nutrients received by reef platforms. They also represent one of the most diverse and productive zones of modern reefs. However, the formation processes and morphodynamics of spur and groove systems are poorly understood, particularly in the Great Barrier Reef (GBR). This paper constitutes the first broad scale analysis of spur and groove systems in the Capricorn Bunker Group (CBG) in the southern GBR. It uses remotely sensed imagery coupled with ground-truthed data to measure groove length at four reefs (Wreck, Heron, One Tree and Lady Elliot). A total of 2621 grooves were digitised across the four study reefs. Groove length was found to vary both between and within the study reefs. The maximum groove length was 536 m. Average groove length ranged from 93 m at Wreck Reef to 32 m at Heron Reef. This data was compared to relative wave exposure estimates derived from the fetch scenario at each reef. Strong positive correlation was found with groove length increasing as wave exposure increased. Groove length was highly spatially dependant and varied around the reef platforms according to the degree of wave exposure. The longest grooves were found on the most exposed, eastern sides of all reefs. These results provide valuable insight into spur and groove function, formation and likely response to future environmental changes in the CBG and further afield. [ABSTRACT FROM AUTHOR]

Duce, S., Vila-Concejo, A., Hamylton, S., Bruce, E., Webster, J. M, 2014. Spur and groove distribution, morphology and relationship to relative wave exposure, Southern Great Barrier Reef, Australia. In: Green, A.N. and Cooper, J.A.G. (eds.), Proceedings 13th International Coastal Symposium (Durban, South Africa), Journal of Coastal Research, Special Issue No. 70, pp. 115-120, ISSN 0749-0208. Spur and groove features occur on the seaward reef slope of coral reefs around the world. They are believed to act as important natural breakwaters, regulating the hydrodynamic energy and nutrients received by reef platforms. They also represent one of the most diverse and productive zones of modern reefs. However, the formation processes and morphodynamics of spur and groove systems are poorly understood, particularly in the Great Barrier Reef (GBR). This paper constitutes the first broad scale analysis of spur and groove systems in the Capricorn Bunker Group (CBG) in the southern GBR. It uses remotely sensed imagery coupled with ground-truthed data to measure groove length at four reefs (Wreck, Heron, One Tree and Lady Elliot). A total of 2621 grooves were digitised across the four study reefs. Groove length was found to vary both between and within the study reefs. The maximum groove length was 536 m. Average groove length ranged from 93 m at Wreck Reef to 32 m at Heron Reef. This data was compared to relative wave exposure estimates derived from the fetch scenario at each reef. Strong positive correlation was found with groove length increasing as wave exposure increased. Groove length was highly spatially dependant and varied around the reef platforms according to the degree of wave exposure. The longest grooves were found on the most exposed, eastern sides of all reefs. These results provide valuable insight into spur and groove function, formation and likely response to future environmental changes in the CBG and further afield. [ABSTRACT FROM AUTHOR]

Pereira, L.C.C., Pinto, K.S.T., Vila-Concejo, A., 2014. Morphodynamic variations of a macrotidal beach (Atalaia) on the Brazilian Amazon Coast. In: Green, A.N. and Cooper, J.A.G. (eds.), Proceedings 13th International Coastal Symposium (Durban, South Africa), Journal of Coastal Research, Special Issue No. 70, pp. 681-686, ISSN 0749-0208. Beach morphology, waves, tides, and current speeds were measured in a moderate-energy macrotidal environment of the Amazon coast (Atalaia beach, Brazil). The study was based on two complementary sets of data: (i) hydrodynamic and topographic data collected in four 25-hour campaigns during equinoctial and non-equinoctial periods, and (ii) climatological data (wind speed and direction, and rainfall) obtained from the Brazilian Institute of Meteorology. The results indicate that tidal currents run predominantly to the northwest during the flood tide and southeast during the ebb. The highest current speeds were recorded during the equinoctial period, reaching a maximum of 0.5 m/s in the flood tide. In March and June (rainiest months), ebb tide currents reached a maximum speed of 0.4 m/s. The tidal cycle was weakly asymmetric with the ebb tide lasting up to 6 hours and 40 minutes. High tides ranged from 4 m (non-equinoctial) to 5.7 m (equinoctial). Wave energy was modulated slightly during the low tide due to wave attenuation on the sandbanks, but substantial changes were not observed during ebb and flood tides. Modal wave height ( Hb) varied from 1.1 to 1.43 m, associated with wave periods of 5.0-7.5s, with the highest values being recorded in November (intense winds). This beach can be classified as tide-modified, presenting primarily dissipative (Ω > 5) characteristic. Wave-dominated characteristics were observed in November, when Hs values were around 1.5 m and tidal elevation was approximately 4 m (non-equinoctial period). [ABSTRACT FROM AUTHOR]

Guerreiro, J.S., Ranieri, L. A., El-Robrini, M., Vila-Concejo. Seasonal changes of a dynamic macrotidal beach: Case Study of Marieta beach(Amazon Coast/Brazil) The Amazon Atlantic Coast is a very dynamic area due to the large discharge associated to a large network of rivers that include the Amazon River. Many of the beaches in this area are located within the area of influence of macrotidal range. There is a large sediment availability that creates extensive tidal flats. Waves are moderate with average offshore of 1.8m. The area has a tropical climate with two seasons, rainy and dry, and is under influence of moderate SE/NE trade winds. This paper presents topographic and hydrodynamic data from one of these beaches, Marieta Beach, and shows that while it undergoes severe erosion during the rainy season, accretion and recovery occurs during the dry season. Erosion seems to be associated to the large river discharge in the rainy season (10 3 to 10 4 m3/s−1), high water levels coupled with strong ebbing currents that remove the sediment from the beach. The beach accumulates large volumes of sediment during the dry season (averaging 15.2 m3); the processes that drive sediment transport are not clear but given that onshore winds occur during this period, it is hypothesized that locally wind- generated waves are capable of transporting sediment back to the beach. Seasonal behavior in this case is associated to the tropical seasonality of the rivers instead of traditional storm/fair weather conditions cycles that are often found in the literature. [ABSTRACT FROM AUTHOR]

Pereira, L.C.C., Vila-Concejo, A.and Short, A.D., 2013. Influence of subtidal sand banks on tidal modulation of waves and beach morphology in macrotidal beaches. Amazon beaches are controlled by large tidal ranges, strong tidal currents and an ample supply of sediments, which create subtidal sand banks that modulate wave energy on the shoreline. Given this, the objective this study was to study the effects of tidal modulation of waves on spatial and temporal beach morphodynamics. This paper presents morphological and hydrodynamic data from three beaches on the Amazon coast of Brazil. Data was taken between November, 2008 and October, 2009. This study has two time scales: short term intensive campaigns with hydrodynamic measurements and topographic surveys and medium term measurements that refer to climatologic and offshore wave data obtained from National Institutes. For the analyses considering the ebb tide and flood tide conditions we have found higher RTR modal values and lower Ω modal values during the ebb tide periods, mainly in the most sheltered beach (higher influence of sand banks), showing the influence of tidal modulation. On the more exposed beach (lower influence of sand banks), a greater influence of wind-wave contributed to a similar pattern among the ebb and flood tide phases, prevailing low tide bar and non-barred dissipative characteristics. On the most sheltered area, the tidal processes dominate maintaining ultradissipative beaches and tidedominated tidal flat. On the macrotidal Amazon beaches tidal elevation and subtidal sand banks modulate the wave energy - during low tide, the waves break offshore on the sand banks and they only start to propagate over the banks when tide is increasing, reaching the maximum wave energy during high tides. [ABSTRACT FROM AUTHOR]

Vila-Concejo, A. Harris, D.L., Shannon, A.M., Webster, J.M., and, Power, H.E., 2013. Coral reef sediment dynamics: evidence of sand-apron evolution on a daily and decadal scale This paper investigates sand apron progradation on decadal and daily scales on a platform reef (One Tree Reef, OTR) located in the southern Great Barrier Reef. The decadal scale is addressed by analysing sand apron progradation using remotely sensed images (aerial photos and satellite imagery) coupled with wind data and cyclone events. The daily scale is addressed through a field campaign that was undertaken in September-October 2011. The campaign consisted of hydrodynamic measurements in three stations over the southern sand apron in OTR. It was found that while there was a small overall progradation over the last 31 years, the progradation had not occurred continuously or consistently along the entire sand apron. Additionally, the effect of cyclones was not clear on the decadal scale. On the daily scale, it was found that currents are generally weak (<0.4 m/s) and that currents during conditions at which suspended sediment is maximized are ocean-ward directed on the central part of the sand apron and lagoon-ward directed on the easternmost end. As such, daily sediment transport does not represent a gross contribution to lagoon infilling by sand apron progradation. Our results show that sand apron progradation does not occur continuously on the decadal or the daily scale. [ABSTRACT FROM AUTHOR]

Harris, D.L. and Vila-Concejo, A., 2013. Wave transformation on a coral reef rubble platform Wave transformation across coral reef platforms is the primary process affecting changes in coral reef geomorphology. Transformation regulates the amount of wave energy entering reef systems, however there have been relatively few hydrodynamic assessments conducted on coral reefs when compared to siliciclastic environments with the effects of common geomorphic features like rubble platforms on wave transformation never specifically examined. This study focuses on the changes in wave characteristics across a rubble platform in a high energy environment (One Tree Reef, southern Great Barrier Reef). Wave conditions were measured at five locations over two days along a cross-reef transect from the reef rim to lagoon. Most of the wave energy was dissipated during wave breaking with energy attenuation due to bottom friction a secondary process. Wave energy attenuation was between 60-99% of the offshore wave conditions only during high tide would wave propagation across the reef platform be capable of affecting reef geomorphology. The wave spectrum also changed with the shorter period gravity wave energy (3 - 20 s) almost completely expending during transformation while longer period infragravity waves (20 - 300 s) were capable of propagating across the reef platform. Wave heights were depth limited and primarily controlled by water depth which suggests that water depth over the reef platform and subsequently elevation of the reef platform above mean sea level govern the amount of wave energy transferred across into reef systems, with most of the gravity wave energy removed during propagation over coral rubble platforms. [ABSTRACT FROM AUTHOR]

An investigation into the evolution of coral rubble deposits on a coral reef platform is assessed using high-resolution remote sensing data and geospatial analysis. Digital change detection analysis techniques are applied to One Tree Reef in the southern Great Barrier Reef by analysing aerial photographs and satellite images captured between 1964 and 2009. Two main types of rubble deposits were identified: (1) rubble flats that are featureless mass accumulations of coral rubble; and, (2) rubble spits that are shore-normal linear features. While both deposits prograde in a lagoon-ward direction, rubble spits move faster (∼2 m/yr) than rubble flats (∼0.5 m/yr). The volume of rubble, the underlying substrate, the energy regime, and storm frequency control the rate of progradation. Rubble flat occurrence is restricted to the high-energy (windward) margin of the coral reef platform, while rubble spits are distributed reef wide, both in modal high energy and modal low energy regions of the reef. Rubble spit deposition is considered to be a result of enlarged spur and groove morphology of the forereef, whereby wave energy is focused through the enlarged groove formations causing the preferential deposition of coral rubble in particular zones of the adjacent reef flat. One last control is thought to be the elevation of the reef crest whereby lower areas are more prone to rubble flat development. A vertical and ocean-ward accumulation of rubble is occurring on the windward margin of the reef leading to a build-up and build-out of the reef, governing the expansion of the reef footprint. This study shows for the first time the evolution of a coral reef rubble flat and rubble spits over decadal time scales as detected through remotely sensed images spanning 45 years. [ABSTRACT FROM AUTHOR]

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Estuarine shorelines are often classified as low-energy coasts and are, therefore, expected to undergo little variation. Port Stephens (SE Australia) is a ria-like drowned river valley microtidal estuary located on a wave-dominated coast. The outer part of the estuary is tide-dominated and has a large shallow flood-tide delta, which is also affected by waves. The northern (predominantly low-energy) shoreline of outer Port Stephens is a continuous stretch of sand comprising areas of high mobility and areas of relative stability terminating in a western extending sand spit. This paper investigates the effects of periodic high-energy conditions during which waves penetrate into the estuary by analysing two types of storms, low to moderate (more frequent type) storms and severe to extreme (low frequency) storms. It is established that low to moderate storms cause generalised erosion over the northern shoreline. On the contrary, severe to extreme storms, while causing erosion on parts of the beach, can transport new sediment across the flood-tide delta and deposit it to build a mobile shore attached sandwave. Long-term (decadal) trends identified in the study area are in agreement with short- and medium-term results. Moving into the estuary are four complementary zones of sediment transport which include: (1) sandwave formation and westward migration; (2) a relatively stable area between the sandwave and an erosion zone; (3) an erosion zone undergoing shoreline retreat and finally (4) a depositional terminus causing westward extension of the sand spit. [ABSTRACT FROM AUTHOR]

The objective of this work is to determine the relative importance of different processes (swash, overwash, aeolian, and lagoon) affecting sediment dynamics in barriers with frequent overwash. Aerial photographs, topographic surveys (with real-time kinematic global positional system), and sample collection were undertaken on Barreta Island (Ria Formosa barrier islands, Portugal). Wave and tidal data were also analysed during a 3-year monitoring period (2001-2004). This 3-year period represents the typical wave conditions of this region. Historical barrier evolution was characterised for the 1947-2001 period. Up until 1996, the supratidal barrier changed from barred sand to fully developed dunes. In 2001, a wide washover plain had developed and an updrift tidal inlet (Ancão Inlet) was migrating toward the study area. Between 2001 and 2004, the study area had three geomorphological sectors. Sector A (westernmost) showed the widest beach berms that developed because of welding of swash bars of Ancão Inlet. Sector B had the widest washover and developed embryonic dunes with well-sorted medium sands. In sector C (easternmost), overwash was more frequent, and induced the deposition of 57 m3/m of sediments (the coarsest of the barrier). Globally, barrier volume variation was mostly due to swash (83%); however, net barrier accretion was 88% induced by overwash. Barrier volume variation was more related to Ancão Inlet evolution than to the seasonality of wave climate. A four-stage conceptual model of barrier evolution under frequent overwash is presented: beach erosion; dune destruction, and formation of washover plain; frequent overwash; and dune development. [ABSTRACT FROM AUTHOR]

The Cacela Peninsula on the south coast of Portugal was, previous to nourishment operations, extremely vulnerable to overwash events. During the 1995-96 winter, extensive overwashing led to the opening of a new inlet. Simultaneously, the lagoon channel in the backbarrier was silting up with the overwash deposits, inlet flood delta sands, and accretion of fine sediments. Between October 1996 and February 1997 the channel was dredged, and the sediments were deposited on the western 2,000 meters of the Cacela Peninsula, forming an artificial dune ridge. The sediment characteristics of the dredge spoils were in contrast with the natural dune sand. The spoils had higher silt and clay content, lower mean grain size, and poorer sorting. In January 1998, three washover breaches were infilled, with sand removed from the foreshore, on the eastern part of the Cacela Peninsula. These sands were coarser and more poorly sorted than the original dune sediments. A 2-year monitoring program, consisting of beach/dune profiling, topographic surveys in specific areas, and sediment analysis, was established to observe the morphological evolution of these areas. The total eroded volume recorded for the dune nourishment project after 2 years was about 106,500 cubic meters, corresponding to 33% of the total 325,000 cubic meters of sediment that was deposited. The washover infilling showed little or no variation. However, the downdrift. beaches and foredunes experienced severe erosion. Both protective measures accomplished their purposes in terms of preventing erosion; however, a natural landscape was only created where dune development by aeolian processes was possible. [ABSTRACT FROM AUTHOR]

Four natural inlets, existing in a multi-inlet, barrier island system, were studied for the period between the 1940s and 1996. Inlet width and position of the inlet channel were determined using a series of vertical aerial photos and charts. The objective of the work was to determine the association between inlet migration patterns and different hydrodynamic conditions, major storms and engineering interventions. Results indicate that natural inlet opening and evolution were mainly affected by three factors: (a) existence of sub-embayments (western and eastern) inside the system, (b) exposure to wave energy, and (c) inlet efficiency. Two distinctive eastward migration patterns were found by analysing the correlation coefficient (r) between inlet width evolution and inlet migration and by the comparison of the shape of the curves fitted to the inlet migration behaviour. Typical migration of the high-energy flank (on the west side of the system) is characterised by an initial stage of readjustment, with low migration rates, followed by a stage of high eastwards migration rates, up to a limiting position. Inlet width remains reasonably constant during the entire migration cycle, thus the correlation between inlet width and position is very low. Typical inlets on the low-energy flank (east side of the system) are formed by barrier breaching during major storms and produce initially very wide inlets. Eastward inlet migration on the low-energy flank follows a natural logarithmic curve where channel migration is accompanied by strong constructional processes on the updrift barrier. Due to subsequent inlet width reductions, the correlation between inlet width and position is significant. [ABSTRACT FROM AUTHOR]

Rubble islands are dynamic sedimentary features present on reef platforms that evolve under a variety of morphodynamic processes and controlling mechanisms. They provide valuable inhabitable land for small island nations, critical habitat for numerous species, and are threatened by climate change. Aiming to investigate the controlling mechanisms dictating the evolution of One Tree Island (OTI), a rubble island in the Southern Great Barrier Reef, we combined different remotely-sensed data across varying timescales with wave data extracted from satellite altimetry and cyclone activity. Our findings show that (1) OTI had expanded by 7% between 1978 and 2019, (2) significant gross planform decadal adjustments were governed by the amount, intensity, proximity, and relative position of cyclones as well as El Niño Southern Oscillation (ENSO) phases, and (3) the mechanisms of island growth involve rubble spits delivering and redistributing rubble to the island through alongshore sediment transport and wave overtopping. Frequent short-term monitoring of the island and further research coupling variations in the different factors driving island change (i.e., sediment availability, reef-wave interactions, and extreme events) are needed to shed light on the future trajectory of OTI and other rubble islands under a climate change scenario. [ABSTRACT FROM AUTHOR]

Robust data are the base of effective gender diversity policy. Evidence shows that gender inequality is still pervasive in science, technology, engineering and mathematics (STEM). Coastal geoscience and engineering (CGE) encompasses professionals working on coastal processes, integrating expertise across physics, geomorphology, engineering, planning and management. The article presents novel results of gender inequality and experiences of gender bias in CGE, and proposes practical steps to address it. It analyses the gender representation in 9 societies, 25 journals, and 10 conferences in CGE and establishes that women represent 30% of the international CGE community, yet there is under-representation in prestige roles such as journal editorial board members (15% women) and conference organisers (18% women). The data show that female underrepresentation is less prominent when the path to prestige roles is clearly outlined and candidates can self-nominate or volunteer instead of the traditional invitation-only pathway. By analysing the views of 314 survey respondents (34% male, 65% female, and 1% "other"), we show that 81% perceive the lack of female role models as a key hurdle for gender equity, and a significantly larger proportion of females (47%) felt held back in their careers due to their gender in comparison with males (9%). The lack of women in prestige roles and senior positions contributes to 81% of survey respondents perceiving the lack of female role models in CGE as a key hurdle for gender equality. While it is clear that having more women as role models is important, this is not enough to effect change. Here seven practical steps towards achieving gender equity in CGE are presented: (1) Advocate for more women in prestige roles; (2) Promote high-achieving females; (3) Create awareness of gender bias; (4) Speak up; (5) Get better support for return to work; (6) Redefine success; and, (7) Encourage more women to enter the discipline at a young age. Some of these steps can be successfully implemented immediately (steps 1–4), while others need institutional engagement and represent major societal overhauls. In any case, these seven practical steps require actions that can start immediately. [ABSTRACT FROM AUTHOR]

Vila-Concejo, A., Short, A.D., Hughes, M.G. and Ranasinghe, R., 2007. Flood-tide Delta Morphodynamics and Management Implications, Port Stephens, Australia. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 705 – 709. Gold Coast, Australia, ISSN 0749.0208 Port Stephens is a drowned river valley estuary located in SE Australia. Its flood-tide delta is part of the morphological transition between the wave-dominated open coast and the tide-dominated estuarine environment. The sand surface of the flood-tide delta is subject to episodic disturbance by large ocean waves that penetrate into Port Stephens. Moreover, the flood-tide delta is a dynamic feature that responds to variations in the forcing mechanisms. Shoal Bay, Nelson Bay and Jimmy's Beach located on both sides of the entrance have experienced severe erosion for the last 40 years, resulting in expensive shoreline management controls. The evolution of these beaches has been linked to the flood-tide delta morphodynamics. Most of the morphologic features in outer Port Stephens have undergone erosion processes during at least the last 40 years. Yacaaba Head seems to be the only morphologic unit that has undergone sedimentary accretion. Results from numerical models obtained by other authors found eastward directed sediment transport occurring on the eroding beaches. Field measurements and observations show westward sediment transport. Further studies to identify the sediment exchange mechanisms and controls are needed to clarify the morphodynamics of the outer part of Port Stephens. [ABSTRACT FROM AUTHOR]