Beach Recovery Research Articles

The extreme 2013/2014 winter storms: Beach recovery along the southwest coast of England

Sand and gravel beaches naturally act as a coastal buffer, absorbing wave energy and dynamically adapting to the seasonal and long-term wave climate. Significant shifts in nearshore morphology can occur during extreme wave events, which can have a significant impact on coastal vulnerability. During the winter of 2013/14, the Atlantic coast of Europe received an unprecedented sequence of very energetic wave conditions (8-week mean offshore Hs=4.4m). These events caused extensive physical (beach and dune erosion) and socio-economic (flooding, damage to infrastructure) impacts throughout the west coast of Europe. Many monitored sites in the UK and France were in their most eroded state since morphological records began (5–10years). We consider the geomorphological significance of the storm response at 38 natural beaches in the southwest of England, ranging from semi-sheltered reflective gravel barriers to ultra-dissipative exposed sand beaches with dunes. The extent and patterns of post-storm recovery are examined in detail at three beaches with characteristic storm response behaviours. Exposed sandy beaches were dominated by cross-shore transport processes leading to significant loss of sediment offshore from the intertidal zone (>200m3/m); exposed gravel beaches were dominated by overwash with significant loss landward; and semi-sheltered sites exposed to more oblique wave forcing were dominated by a rotational response due to alongshore sediment redistribution. Due to these contrasting responses, mechanisms and timescales for beach recovery displayed strong inter-site and intra-site variations. In offshore and rotational cases, the recovery processes were multi-annual, comprising seasonal to decadal signals and were intrinsically linked to the storm response mechanisms, while permanent losses occurred when overwash dominated. We show that post-storm recovery does not necessarily occur during calm periods and that in many cases high-energy wave events appear to be essential for recovery of sediment (offshore and counter-rotation). Our results highlight the significance of dominant climatic oscillations, multi-annual storm sequencing, storm tracks and resultant variations in wave angle, in controlling the impact that extreme wave events have on contrasting sand/gravel beaches in exposed/sheltered locations.

The role of community leadership in disaster recovery projects: Tsunami lessons from Japan

While project management has been effectively applied to many fields and sectors, disaster management has yet to see its full benefits. This inductive study generates insights about the nature and role of ‘active leadership’ (LaBrosse, 2007) in the context of a community led recovery project in Minami-sanriku, Japan, an area affected by the 2011 tsunami. Community leaders displayed ‘active leadership’ evidenced in 1) the effective identification of project objectives and relevant stakeholders, 2) the efficient management of stakeholder engagement and 3) the robust understanding of the socio-cultural context in which the Nagasuka Beach Recovery Project took place. This multi-disciplinary and inductive study highlights the need to train project managers (be they community leaders or otherwise) in both technical and soft leadership skills: the former ensure that Project Management methodologies are clearly understood and applied; the latter facilitate the adaptation of these methodologies to the specific socio-cultural locales in which recovery projects take place.

Morphological changes, beach inundation and overwash caused by an extreme storm on a low-lying embayed beach bounded by a dune system (NW Mediterranean)

The geomorphological evolution of a low-lying, micro-tidal sandy beach in the western Mediterranean, Pals beach, was characterized using airborne Light Detection and Ranging (LiDAR) data. Data were collected in prior to and six months after the impact of an extreme storm with a return period of approx. 50years, with the aim of characterizing the beach's response to the storm. The use of repeated high-resolution topographic data to quantify beach geomorphic changes has allowed assessment of the accuracy of different proxies for estimating beach volume changes. Results revealed that changes in the shoreline position cannot accurately reproduce beach volume changes on low-lying beaches where overwash processes are significant. Observations also suggested that volume estimations from beach profiles do not accurately represent subaerial volume changes at large profile distances on beaches with significant alongshore geomorphological variability. Accordingly, the segmentation of the beach into regularly spaced bins is proposed to assess alongshore variations in the beach volume with the accuracy of the topographic data. The morphological evolution of Pals beach during the study period showed a net shoreline retreat (−4m) and a significant sediment gain on the subaerial beach (+7.5m3/m). The net gain of sediment is mostly due to the impact of the extreme storm, driving significant overwash processes that transport sediment landwards, increasing volume on the backshore and dunes. The increase of volume on the foreshore and the presence of cuspate morphologies along the shoreline also evidence post-storm beach recovery. Observed morphological changes exhibit a high variability along the beach related to variations in beach morphology. Changes in the morphology and migration of megacusps result in a high variability in the shoreline position and foreshore volume changes. On the other hand, larger morphological changes on the backshore and larger inundation distances occur when the beach and the dunes are lower, favouring the dominance of overwash. The observed storm-induced morphological changes differ from predicted beach storm impacts because of spatial and temporal variations in the beach morphology, suggesting that detailed morphological parameters and indicators used for predicting beach vulnerability to storms should be regularly updated in order to represent the pre-storm beach conditions. Finally, observed morphological changes in Pals Bay evidenced a different behaviour between natural and urban areas, with better post-storm beach recovery on natural areas where the beach is not artificially narrowed.

Shoreline variability of an urban beach fronted by a beachrock reef from video imagery

This contribution presents the results of a study on the shoreline variability of a natural perched urban beach (Ammoudara, N. Crete, Greece). Shoreline variability was monitored in high spatio-temporal resolution using time series of coastal video images and a novel, fully automated 2-D shoreline detection algorithm. Ten-month video monitoring showed that cross-shore shoreline change was, in some areas, up to 8 m with adjacent sections of the shoreline showing contrasting patterns of beach loss or gain. Variability increased in spring/early summer and stabilized until the end of the summer when partial beach recovery commenced. Correlation of the patterns of beach change with wave forcing (as recorded at an offshore wave buoy) is not straightforward; the only discernible association was that particularly energetic waves from the northern sector can trigger changes in the patterns of shoreline variability and that increased variability might be sustained by increases in offshore wave steepness. It was also found that the fronting beachrock reef exerts significant geological control on beach hydrodynamics. Hydrodynamic modelling and observations during an energetic event showed that the reef can filter wave energy in a highly differential manner, depending on its local architecture. In some areas, the reef allows only low-energy waves to impinge on the shoreline, whereas elsewhere penetration of higher waves is facilitated by the low elevation and limited width of the reef or by the presence of an inlet. Wave/reef interaction can also generate complex circulation patterns, including rip currents that appeared to be also constrained by the reef architecture.

The influence of fluvial dynamics and North Atlantic swells on the beach habitat of leatherback turtles at Grande Riviere Trinidad

Grande Riviere beach, located on the north coast of Trinidad, West Indies, is internationally recognised as a critical habitat/nesting ground for the endangered leatherback turtles (Dermochelys coriacea). Episodic extreme flooding of the Grande Riviere River led to the shifting of the river mouth and resulted in backshore beach erosion, with the most recent recorded event occurring in 2012. Following this event, the construction of a sand dam to arrest further erosion which threatened coastal infrastructure, precipitated a host of new problems ranging from beach instability to public health threats. In January 2013, high energy swell waves naturally in-filled the erosion channel, and the beach recovery continued over the successive months, thereby rendering the intervention in the previous year questionable. This paper presents a geomorphological analysis of beach dynamics for Grande Riviere, within the context of this erosion event. Data on beach profiles, sediment and coastal processes were collected using standard geomorphological techniques. Beach topographic analysis and water quality tests on impounded water in the erosion channel were conducted. Results indicate that the event created an erosion channel of 4843.42 m3 over a contiguous area of 2794.25 m2. While swell waves were able to naturally infill the channel, they also eroded 17,762 m3 of sand overall across the beach. Water quality tests revealed that the impounded water was classified as a pollutant, and created challenges for remediation. Hydrologic and coastal geomorphologic interplay is responsible for the existence and sustainability of this coastal system. It is also evident that the beach system is able to recover naturally following extreme events. Our results demonstrate that effective and integrated management of such critical habitats remains dependent upon continuous monitoring data which should be used to inform policy and decision making.

GIS based beach sand budget analysis through seasonal beach profiling using cartographic techniques

Seasonal morphological variations and effect of oceanographic processes such as erosion or accretion along beaches are important aspects to understand the sand budget. The nature of the beach and their seasonal cyclic changes are probable reasons of seasonal morphological variations. The primary objective of the present study is to estimate coastal beach sand budget using Geoinformatics techniques. The study area is 113 km long coastal belt covering parts of Midnapore–Balasore coast. The field data has been collected using GPS and Theodolite, following standard cartographic techniques. Besides, Remote Sensing and GIS techniques have been used in identifying the coastal features, mapping and spatial analysis. Therefore, eighteen beach profiles have been taken during the post and pre-monsoon seasons of the year 2008 and 2009. Within the specific zones, beach erosion and/or accumulation between post and pre-monsoon season has been quantified. The result shows that up to pre-monsoon season, the beach is significantly recovered with gradual decrease in beach gradient. Further, along each profile Digital Elevation Models corresponding to post and pre monsoons periods have been generated, which has subsequently utilized in the estimation of beach recovery along each profile and also estimation of beach sand budget of the study region.

Analysis of short-term shoreline oscillations along Midnapur-Balasore Coast, Bay of Bengal, India: a study based on geospatial technology

Shoreline is one of the quickly fluctuating linear landscapes of the coastal zone which is active in nature. In the present study, the analysis of remote sensing data sets covering Midnapur-Balasore coast, with an average time span of 6 months, has shown that they can be used to evaluate the short-term shoreline oscillations. In the present study, multi temporal satellite images of Landsat have been used to demarcate the short-term position of the shoreline changes. The techniques such as littoral cells, shore line change rate and beach recovery and devastation concept has been applied in this study. Finally the use of remote sensing data has proven as a good technique to estimate and quantify short-term shoreline oscillations along Midanpur-Balasore coast.

Analysis of Coastal Erosion due to the 2011 Great East Japan Tsunami and its Recovery Using Ground Penetrating Radar Data

ABSTRACT Takamura, M.; Udo, K.; Sato, M., and Takahashi, K., 2016. Analysis of Coastal Erosion due to the 2011 Great East Japan Tsunami and Its Recovery Using Ground Penetrating Radar Data. 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. 477–481. Coconut Creek (Florida), ISSN 0749-0208. The 2011 Great East Japan Tsunami caused severe beach erosion along the Pacific coast. Eroded beaches began to recover rapidly after the tsunami, but the rate of beach recovery declined recently. We conducted a ground-penetrating radar (GPR) and borehole survey at Yamamoto Beach, which was eroded by the 2011 tsunami, to understand the tsunami recovery process using a new method that combines GPR, satellite images or aerial photographs, and tidal data. We compared reflective surfaces with geological layers observed using the GPR and borehole survey, respectively, to...

Effects of storm clustering on beach/dune evolution

Impacts of storm clustering on beach/dune morphodynamics were investigated by applying the state-of-the-art numerical model XBeach to Formby Point (Sefton coast, UK). The adopted storm cluster was established by analysing the observed winter storms from December 2013 to January 2014 using a storm threshold wave height. The first storm that occurred during this period is regarded as exceptionally intense, and the occurrence of such a cluster of events is very unusual. A 1D model was setup for the highly dynamic cross-shore at Formby Point. After initial calibration of the model parameters against available post-storm profile data, the model was used for the simulation of the storm cluster. It was assumed that no beach recovery occurred between adjacent storms due to the very short time intervals between storms. As a result, the final predicted post-storm profile of the previous storm was used as the pre-storm profile of the subsequent storm. The predicted evolution during each storm was influenced by the previous storms in the cluster. Due to the clustering effect, the bed level change is not proportional to the storm power of events within the cluster, as it would be in an individual storm case. Initially, the large storm events interact with the multi-bared foreshore enabling the subsequent weaker storms to influence the upper beach and lower dune system. This results in greater change at the dune toe level also during less severe subsequent storms. It is also shown that the usual water level threshold used to define dune erosion is over predicted by about 1m for extreme storm conditions. The predicted profile evolution provides useful insights into the morphodynamic processes of beach/dune systems during a storm cluster (using Formby Point as an example), which is very useful for quantifying the clustering effects to develop tools for coastal management.

Post-earthquake coastal evolution and recovery of an embayed beach in central-southern Chile

Earthquakes and tsunamis are significant factors for change along active margin shores, and influence coastal evolution. The Chilean coast was affected in 2010 by a subduction earthquake with a magnitude of Mw8.8 and also by a trans-Pacific tsunami, which generated violent geomorphologic changes and damaged homes. Following these events, the magnitude of the changes which affect Chile's central-southern coast (37°S) and the role of subduction earthquakes in coastal evolution on a historical scale were investigated.At Lebu bay (an embayed beach) data were generated for variations in time and space along the shoreline, topographical and bathymetric changes in the bay, and for morphodynamic littoral processes. Logarithmic and parabolic models were applied to the shoreline along with map overlays in order to determine changes. The shoreline processes were analyzed based on statistics for waves, tides and sediment transport for pre- and post-tsunami conditions.An average accretion rate of 2.80m/year (1984–2010) was established for the shoreline, with a strong trend towards accretion in the last 30years. A parabolic function best represented the general form of the shoreline, although the presence of a river in the concave zone affected the fit in this sector. Two factors controlled historical changes on the beach: one of anthropic origin in addition to the earthquake and tsunami on February 27th, 2010. The post-earthquake recovery was fast, and currently the beach is in a stable condition despite the inter-seismic subsidence process previous to the event. This coastal system showed a high resilience in the face of coastal geomorphological changes induced by high-impact natural disturbances. However, the opposite occurred in relation to changes induced by anthropogenic disturbances.

New insights into embayed beach rotation: The importance of wave exposure and cross‐shore processes

AbstractAlthough embayed beach rotation has been viewed and modeled as an alongshore sediment transport process acting on a uniform beach profile, recent research suggests a more complex response whereby alongshore variability in cross‐shore sediment fluxes may be more significant. This study utilizes 5 years of fully three‐dimensional beach surveys at Narrabeen‐Collaroy Beach (SE Australia) to quantify the control of alongshore nonuniform wave exposure and cross‐shore processes on embayed beach rotation. Empirical orthogonal function analysis of the alongshore variability in subaerial beach volume/width and berm slope confirms that the dominant mode of subaerial beach variability is an onshore/offshore sediment exchange that is strongly controlled (R > 0.8) by the alongshore gradient in breaker wave height and coincides with a uniform flattening/steepening of the berm slope. A secondary rotation‐like signal is observed in both the subaerial beach volume/width data and, significantly, the berm slope. This inverse flattening/steepening of the berm slope between beach extremities is most likely a proxy for differing cross‐shore processes within the surf zone between the exposed and sheltered ends of the embayment, particularly with regards to dissipation of storm wave energy by offshore sandbars and beach recovery following storms. Analysis of the corresponding wave data reveals two distinct time scales of wave forcing characteristic of short‐term erosion and longer‐term recovery processes. A new conceptual model is presented of three differing modes of embayed beach rotation, with the newly identified beach rotation mode controlled by offshore sandbars considered of particular importance at embayments where headland sheltering of oblique waves is pronounced.

MODELLING BEACH MORPHODYNAMICS FOR SOUTHERN GOLD COAST BEACH NOURISHMENT PROJECT AT BILINGA BEACH

A new cross shore process model NSBEACH (New SBEACH) has been applied to the Southern Gold Coast Nourishment Project at Bilinga beach (Australia) where nearshore nourishment and bar movement with beach berm and dune building have been simulated. Following the extension of the Tweed River training walls in the late 1960s, the downdrift Southern Gold Coast beaches to the north suffered extensive and prolonged erosion. Between 1988 and 1996, 6.6 million m3 of sand was deposited in both onshore and nearshore locations along the beaches of the Southern Gold Coast. Extensive post-nourishment beach monitoring data shows the recovery of Bilinga beach with the nearshore nourished material transported onshore. There have been many unsuccessful attempts to numerically model the beach recovery processes following the nearshore nourishment on the Southern Gold Coast. Most coastal models have been developed for prediction of storm erosion and as such have limited abilities in simulating bar movement and onshore accretion with beach recovery over extended periods of time. NSBEACH (New SBEACH) has been developed with the ability to simulate short term storm erosion and the longer duration recovery processes under natural or nourished conditions. NSBEACH has been successfully applied at Bilinga beach over an extended simulation period of 8 months with both erosion and accretion responses of the beach successfully simulated.

Storm impact on the seasonal shoreline dynamics of a meso- to macrotidal open sandy beach (Biscarrosse, France)

A three-year dataset (2007–2010) of shoreline and sandbar positions derived from video observations of an open sandy beach (Biscarrosse, France) is analyzed, to explore the impact of storms on the seasonal shoreline dynamics. The results indicate that a clear seasonality is observed in the offshore significant wave height and in the occurrence of ‘winter storm’ events that are defined as periods with significant wave height greater than 4m lasting at least 12h. Data indicate that the range of variation of the inner sandbar positions (120m) is two and a half times larger than the range of variation of the shoreline position. Correlation analyses suggest that the offshore conditions do not conclusively explain the position of the inner bar. Shoreline positions show a clear seasonal pattern, displaying a stable position occurring in February and July, providing evidence of seasonal-recovery although analysis of storm activity indicates that the number and intensity of storms is highly variable over the three years. The Biscarrosse data show that rapid erosion can be observed also under moderate conditions, and that beach recovery after the storm season can be relatively rapid.

Status of intertidal infaunal communities following the Exxon Valdez oil spill in Prince William Sound, Alaska

Intertidal infaunal communities were sampled in Prince William Sound, Alaska from 1990–2000 to evaluate impacts and recovery from the Exxon Valdez oil spill. Initial findings suggested that the spill and cleanup depressed abundances of all taxonomic groups. By 1992, abundances of major taxonomic categories at disturbed sites had either converged or paralleled populations at Unoiled sites. Abundances of littleneck clams, Leukoma (Protothaca) staminea, slowly increased at Treated sites and converged with Unoiled sites by 2000. Infaunal population differences positively correlated with fine-grained sediments at Treated sites. We believe that sediment fines removal during cleanup, and subsequent slow natural replenishment, impeded the return of the environment to pre-spill conditions. This suggests physical recovery of spill-affected beaches is an important precursor to biological recovery.

Evaluation of storm impact on sandy beaches of the Gulf of Valencia using Landsat imagery series

The impact of storms on sandy beaches and the subsequent recovery process is described from an analysis of the shoreline positions obtained from Landsat 5 TM and Landsat 7 ETM+ imagery. Shoreline extraction is based on an algorithm previously proposed by the authors that enables a positioning accuracy of 5m root mean square error (RMSE). The impact of six storms registered over a period of seven months (between November 2001 and May 2002) and the beach recovery processes until December 2002 across a 100km segment of the Gulf of Valencia on the Spanish Mediterranean coast were analysed by comparing 12 shoreline positions. The multiple shoreline positions obtained from Landsat images provide very useful information for describing the impact of storms and the recovery process across large segments of microtidal coast. This enables the identification of differences not only in the magnitude of change produced by a particular event but also in the cumulative effect associated with several storm events, and in the study of how the beach recovery process takes place. The results show a high level of spatial variability. Beaches with steep slopes experienced fewer changes than shallow slopes. The existence of well developed foredunes in some areas minimised the reduction in the beach width after the storms. Coastal orientation was another important factor in explaining storm impact and the recovery process. This factor affects not only the way the waves interact with the beaches but also the sediment longshore transport: beach regeneration is slower when the transport of sediments is limited by artificial infrastructures (groins, jetties, ports) or natural sediment traps (headlands). The main limitations of using the proposed methodology to obtain the shoreline position from Landsat images are related to: (i) the precision in the shoreline detection; (ii) the nature of the indicator obtained, that is, the water/land interface; and (iii) the registration instant defined by the image acquisition time. However, the high frequency of the data acquisition and the possibility to cover large coastal areas bring a new perspective that enriches other methods and tools used by coastal scientists.

津波来襲後の広域漂砂系の変容

Recovery of sandy beach from severe erosion by the 2011 tsunami can be observed on Sendai Coast even 3 years after the tsunami. The long-term effect of such a severe morphology change on sediment transport system is investigated through analysis of aerial photographs. Empirical Orthogonal Function (EOF) analysis is applied to shoreline positions extracted from the aerial photographs. The first and third modes express the recovery process of shoreline from the severe erosion with respective time-scale, and the superposition of their contribution rate is more than 70%. Comparison of shoreline change rate before and after the tsunami clearly shows that the recovery process of severely eroded area caused completely different trend of sediment transport processes.

二宮海岸での粗粒材養浜による砂浜復元の実証実験

二宮海岸での粗粒材養浜による砂浜復元の実証実験

Burrowing inhibition by fine textured beach fill: Implications for recovery of beach ecosystems

Beach nourishment is often considered the most environmentally sound method of maintaining eroding shorelines. However, the ecological consequences are poorly understood. Fill activities cause intense disturbance and high mortality and have the potential to alter the diversity, abundance, and distribution of intertidal macroinvertebrates for months to years. Ecological recovery following fill activities depends on successful recolonization and recruitment of the entire sandy intertidal community. The use of incompatible sediments as fill material can strongly affect ecosystem recovery. We hypothesized that burrowing inhibition of intertidal animals by incompatible fine fill sediments contributes to ecological impacts and limits recovery in beach ecosystems. We experimentally investigated the influence of intertidal zone and burrowing mode on responses of beach invertebrates to altered sediment texture (28–38% fines), and ultimately the potential for colonization and recovery of beaches disturbed by beach filling. Using experimental trials in fill material and natural beach sand, we found that the mismatched fine fill sediments significantly inhibited burrowing of characteristic species from all intertidal zones, including sand crabs, clams, polychaetes, isopods, and talitrid amphipods. Burrowing performance of all five species we tested was consistently reduced in the fill material and burrowing was completely inhibited for several species. The threshold for burrowing inhibition by fine sediment content in middle and lower beach macroinvertebrates varied by species, with highest sensitivity for the polychaete (4% fines, below the USA regulatory limit of 10% fines), followed by sand crabs and clams (20% fines). These results suggest broader investigation of thresholds for burrowing inhibition in fine fill material is needed for beach animals. Burrowing inhibition caused by mismatched fill sediments exposes beach macroinvertebrates to stresses, which could depress recruitment and survival at all intertidal zones. Our results suggest use of incompatible fine fill sediments from dredging projects creates unsuitable intertidal habitat that excludes burrowing macroinvertebrates and could delay beach ecosystem recovery. Through effects on beach invertebrates that are prey for shorebirds and fish, the ecological impacts of filling with mismatched fine sediments could influence higher trophic levels and extend beyond the beach itself.

A comparison of the post-storm recovery of two sandy beaches on Hong Kong Island, southern China

Typhoon Hagupit was one of six tropical cyclones that affected Hong Kong in 2008. When the typhoon made landfall, the combined effect of the waves, storm surge and seasonal high tides resulted in a maximum sea level of 3.53 m at the nearest tide gauge to the study site, the highest since 1962. The event caused considerable damage to coastal infrastructure and large-scale erosion on many sandy beaches in Hong Kong. To study the degree of erosion and recovery of Hong Kong beaches, we surveyed two sandy beaches: Tai Long Wan (TLW), a relatively high-energy exposed beach system, and To Tei Wan (TTW), a relatively low-energy Sheltered beach system. We examined the two beaches for changes in their beach profiles and sediment properties. TLW recovered quickly, with significant post-storm accretion of fine- to medium-grained sand. Within four months after the typhoon, TLW regained >700 m3 sand, forming a new, ∼1.0 m high, berm, with the beach face prograding approximately 5.0 m seaward. In contrast, within the same four months after the typhoon, TTW showed little evidence of sand accretion or recovery, with only minor changes in the beach profile. In fact, instead of post-storm sand accretion, the landward migration of the high tide mark shown in the pre- and post-storm satellite images suggested that the post-storm beach elevation at TTW decreased. The results, which reflect the different background energy regimes of each beach, indicate that different coastal management strategies should be applied. In the case of relatively high-energy beaches of Hong Kong, we suggest not interfering with their natural state. In contrast, in the case of relatively low-energy beaches of Hong Kong, which appear unlikely to recover rapidly from erosion during storms, we suggest further investigation before applying any long- to medium-term management strategies.

Airflow reversal and alternating corkscrew vortices in foredune wake zones during perpendicular and oblique offshore winds

On all sandy coastlines fringed by dunes, understanding localised air flow allows us to examine the potential sand transfer between the beach and dunes by wind-blown (Aeolian) action. Traditional thinking into this phenomenon had previously included only onshore winds as effective drivers of this transfer. Recent research by the authors, however, has shown that offshore air-flow too can contribute significantly, through lee-side back eddies, to the overall windblown sediment budget to coastal dunes. Under rising sea levels and increased erosion scenarios, this is an important process in any post-storm recovery of sandy beaches. Until now though, full visualisation in 3D of this newly recognised mechanism in offshore flows has not been achieved. Here, we show for the first time, this return flow eddy system using 3D computational fluid dynamics modelling, and reveal the presence of complex corkscrew vortices and other phenomena. The work highlights the importance of relatively small surface undulations in the dune crest which act to induce the spatial patterns of airflow (and transport) found on the adjacent beach.