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Warner, A.L.; Hesp, P.A.; Keane, R., and Gontz, A.M., 2022. Ground penetrating radar of paleoblowouts and transgressive dunes, Younghusband Peninsula, South Australia. Journal of Coastal Research, 38(5), 885–895. Coconut Creek (Florida), ISSN 0749-0208. Ground penetrating radar (GPR) can be used to elucidate the spatial and temporal relationships of paleoshorelines and dunefield evolution and aid in understanding past landscapes in order to help predict future evolutionary pathways of barrier development. GPR was used on the Younghusband Peninsula coast of Southern Australia at a location known as 42 Mile Crossing. The barrier is on the longest beach in Australia and hosts a Holocene transgressive dunefield system. The site also contains many active, modern, and stabilized blowouts. This study aimed to image buried (paleo) blowouts, analyze the subsurface strata of the area, and attempt to relate these findings to the past transgressive dunefield processes, phases, and architecture. The study was able to characterize the buried blowout's shape, size, and dominant wind direction, and the site's stratigraphic evolution. [ABSTRACT FROM AUTHOR]

DaSilva, M.; Miot da Silva, G.; Hesp, P.A.; Bruce, D.; Keane, R., and Moore, C., 2021. Assessing shoreline change using historical aerial and RapidEye satellite imagery (Cape Jaffa, South Australia). Journal of Coastal Research, 37(3), 468–483. Coconut Creek (Florida), ISSN 0749-0208. The coastal zone is a dynamic area which can experience substantial natural change in short time periods, but changes are also associated with human modifications to the coastline. This case study is focused around assessing shoreline change associated with the Cape Jaffa Marina and canal estate in South Australia. The research comprises a GIS based analysis of shoreline change utilising aerial imagery from 1975 to 2005, which provides information of the morphological coastal trends prior to construction in 2008 of the marina/canal estate. In addition, imagery collected by the RapidEye satellite constellation was used to assess shoreline changes in the decade since construction, 2009 to 2019. The shoreline change statistics over the past few decades were calculated using the Digital Shoreline Analysis System extension of ESRI's ArcGIS. The image analysis workflow is based on the objective extraction of shoreline proxies from individual image statistics in a semi-automated process and is used to identify the waterline and edge of vegetation shoreline proxies in a time series analysis. The results provide a case study of a historically progradational sandy coastline experiencing substantial amounts of alongshore sediment transport, the corresponding obstruction from coastal infrastructure, and the resulting morphological changes to the Cape Jaffa shoreline. Shoreline change trends were altered from a predominantly accretional shoreline before the construction of the marina to one oscillating between extremes of erosion and accretion. The results showed significant accretion occurring updrift (Net Shore Movement (NSM) of 106 m) and significant erosion downdrift (NSM of –80 m) of the marina's training walls and entrance. The information derived from Earth observation satellites, such as RapidEye, can provide valuable insights into trend analysis due to their relatively high spatial (5 metre) and temporal resolution (5.5-day revisit). [ABSTRACT FROM AUTHOR]

Hesp, Patrick A. and Smyth, T.A.G., 2016. Surfzone-Beach-Dune interactions: Review; and flow and sediment transport across the intertidal beach and backshore. 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.8-12. Coconut Creek (Florida), ISSN 0749-0208. The original wave-beach-dune model (Hesp, 1982) stated that in the medium to long term, modal dissipative beaches display maximum onshore wave driven sediment transport, maximum aeolian transport off beaches, the largest foredune heights and volumes, and the largest Holocene dunefields. Modal reflective beaches display the opposite, while modal intermediate beaches display a trend in these from relatively high to relatively low sediment transport, foredune volumes, and Holocene barrier volumes with a trend from dissipative to reflective. New Computational Fluid Dynamic (CFD) modelling of flow and calculation of sediment transport over three modal beach types presented here shows that the original conceptual ideas and field data regarding aeolian sediment transport are correct. Dissipative beaches show the greatest long term potential for sediment delivery to the backshore whilst reflective beaches display the least, with a trend from relatively high to low in the intermediate beach state range. [ABSTRACT FROM AUTHOR]

Hesp, Patrick A.; Smyth, Thomas A.G.; Walker, Ian J.; Gares, Paul A., and Wasklewisz, Thad, 2016. Flow within a trough blowout at Cape Cod. 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. 288-292. Coconut Creek (Florida), ISSN 0749-0208. The Province Lands dunefield at Cape Cod is characterised by large parabolic dunes on which have developed very significant numbers of active saucer and bowl blowouts. Blowouts occur across the entire dune landscape but many are initiated on the high lee margins of large erosional ridges and bowl blowouts within the larger parabolic dune landscape. Evolution of these blowouts is characterised by multiple stages. The first few evolutionary stages are described. In addition, the aerodynamics and flow structure within a trough blowout and former saucer blowout developed within a high ridge crest is elucidated from 2D sonic anemometer data, smoke bombs and videography. The flow is characterised by decreasing then increasing flow up the blowout centreline, and marked, highly turbulent opposed flow separation immediately inside and around the marginal entrance walls of the blowout. [ABSTRACT FROM AUTHOR]

Smyth, T.A.G. and Hesp, Patrick A., 2016. Numerical Modelling of Turbulent Flow Structures in a Blowout. 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. 328-332. Coconut Creek (Florida), ISSN 0749-0208. Blowouts are erosional landforms often formed on coastal sand dunes by the deflation of sediment by wind flow. Quantitative observations of wind flow within blowouts aided by the deployment of smoke-bombs, have noted that temporal and spatial variations in sediment transport occur with the presence of turbulent flow structures. However because of the discrete nature of anemometry data, the presence of flow structures has been difficult to quantify and our understanding remains largely conceptual. This study presents a detailed investigation of turbulent flow structures within a trough blowout using high resolution, three-dimensional computational fluid dynamic modelling. We show that when incident wind flow was parallel to the blowout axis, only limited flow steering took place but a well-defined near surface jet developed along the deflation basin. Conversely when incident wind flow was oblique to the axis of the blowout wind flow became steered along the axis of the blowout but no near surface jet was produced. During neither incident wind direction were corkscrew or helicoidal vortices produced. Our study concludes that the incident wind flow direction is critical to the effectiveness of a trough blowout as a corridor for wind-blown sediment. While wind from a range of oblique angles may be steered along the axis of blowout, its relative effectiveness of eroding and transporting sediment beyond the deflation basin and erosional walls is much reduced compared to axis parallel wind flows of the same incident wind speed. [ABSTRACT FROM AUTHOR]

Dillenburg, S.; Hesp, P.; Cecílio, R., and Miot da Silva, G., 2016. Wave Energy as a Control on Dune Development on two Regressive Barriers in Southern Brazil. 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. 273-277. Coconut Creek (Florida), ISSN 0749-0208. Two regressive barriers (Cassino and Curumim) were developed during the middle and late Holocene along gentle re-entrants of the Rio Grande do Sul coast, and they have prograded up to 17 km and 5 km, respectively. While Cassino is marked by a surface morphology characterised predominantly by foredune ridges, Curumim displays a surface completely covered by widely spaced ridges, corresponding to phases of transgressive dunefield formation. As wave period and shoreline orientation are very similar for both barriers, and considering that they are subjected to the same deepwater wave climate, the substantial surface morphological differences between the barriers is, at least in part, a direct consequence of variations in wave height at the two sites. In addition, there is a significant difference in potential sand transport and wind power between the two sites. As transgressive dunefields and parabolic dunes can develop as a consequence of foredune destabilization, followed by wind action, it is very possible that at Cassino, during barrier development storm waves were not strong enough to destabilised the foredune system and, in addition, if storm scarping occurred, winds were not competent to destabilise the foredunes, thus providing conditions for the formation predominantly of a foredune ridge plain. Only occasionally, presumably during very strong storms (or multiples thereof), foredune destabilization has resulted in dune transgression. At Curumim, either storm waves and higher wind strengths were more effective in dune destabilization, or foredunes rarely developed allowing the formation of multiple phases of transgressive dunefields during barrier progradation. [ABSTRACT FROM AUTHOR]

Silva, R.; Martínez, M.L.; Hesp, P.; Catalan, P.; Osorio, A. F.; Martell, R.; Fossati, M.; Miot da Silva, G.; Mariño-Tapia, I.; Pereira, P.; Cienfuegos, R.; Klein, A., and Govaere, G., 2014. Present and future challenges of coastal erosion in Latin America. The coastal zones of Latin America have many landforms and environments, including sedimentary cliffs, deeply incised estuaries, headlands, barrier coasts and low lying, muddy coastal plains. These forms will respond differently to the expected changes in climate and associated sea level rise, which may produce coastal erosion in the future. Considering the coasts of Latin America overall, erosion is not yet a serious threat, although it is widespread and it is severe in some parts. Major erosion problems are frequently associated with human intervention in sediment supply, with poor planning or with the morphodynamic nature of the coast. Permanent erosional processes, locally or regionally, are caused by tectonic subsidence, deforestation and the fragmentation of coastal ecosystems, land use changes and sediment deficits because of infrastructure built along the coast. In this article we analyse coastal erosion in Latin America and the challenges it presents to the region. We first highlight the relevance of Latin America in terms of its biodiversity; then we describe the population at risk, demographic trends and economic growth throughout the low lying coastal zones. We also examine the vulnerability of the region by analyzing the resilience of key coastal ecosystems after exposure to the most frequent hazards that affect coastal zones in Latin America, namely tropical cyclones, sea level rise, ocean acidification, earthquakes and tsunamis. Finally, we discuss seven case studies of coastal erosion across Latin America. We close the study by pinpointing the main areas of concern in Latin America and explore possible strategies to overcome erosion and thus sustain economic growth, minimize population risk and maintain biodiversity. [ABSTRACT FROM AUTHOR]

Hesp, P.A., 2013. A 34 year record of foredune morphodynamics at Dark Point, NSW, Australia In: Conley, D.C., Masselink, G., Russell, P.E. and O'Hare, T.J. (eds.) Incipient foredunes are formed by æolian deposition in plants on the backshore. They commonly evolve into established foredunes, and are present on many of the world's coasts, yet there are very few medium to long term studies on how they evolve and change over time. An incipient foredune suite has been monitored at Dark Point, NSW, Australia since 1978, providing a 34 year record of dune evolution and dynamics, and therefore representing one of the very few medium term foredune monitoring sites in the world. The foredune was initiated by the growth of a zone of discrete pioneer plant species (principally Spinifex) on the backshore following the destructive 1974-75 storms. Over a period of 24 years, 5 separate incipient foredunes developed as sediment was gradually returned to the surfzone and beach, and the beach prograded 70m. Sometime after 1998, storms cut back the seawardmost foredune and former foredunes were reactivated landwards of the 1998 foredune. This study demonstrates (i) how incipient foredunes form by both discrete seedling development, and seawards rhizome extension over time, (ii) how ramp and terrace morphologies eventually evolve into ridges, (iii) rates of beach accretion following storm erosion and backshore response, (iv) how wave erosion drives morphological changes and evolutionary sequences on foredunes, (v) the relationships between backshore height, foredune development and sea levels, and (vi) indications for the initiation and evolution of so-called 'beach ridges'. [ABSTRACT FROM AUTHOR]

Miot da Silva, G., Hesp, P., Keim, B., Martinho, C.T. and Ferligoj, Y., 2013. Changes in dunefield geomorphology and vegetation cover as a response to local and regional climate variations. In: Conley, D.C., Masselink, G., Russell, P.E. and O'Hare, T.J. (eds.) Published analyses of aerial photographs show a marked increase in vegetation cover of coastal transgressive dunefields along the Southern Brazilian Holocene Barrier around the late 1970s. This phenomenon is reflecting an increase in precipitation and a decrease in aeolian sediment transport. These climatic changes are associated with recurring high intensity El Niño events related to the 1976/1977 regime shift of the Pacific Decadal Oscillation (PDO). [ABSTRACT FROM AUTHOR]

This paper aims to verify how wave energy and longshore sediment transport rates could have influenced the evolution of the Rio Grande do Sul Holocene barriers in the last 5000 y, assuming that wave climate conditions did not change much during the Middle and Late Holocene. Calculations of wave energy based on visual observations and longshore sediment transport show that both wave energy and sediment transport decrease as the coastline becomes concave (embayed) and increase as the coastline becomes convex (projected). These variations alongshore create a positive and negative imbalance, respectively, in the sediment budget. The long-term operation of these processes has produced progradational barriers in embayments and retrogradational barriers along projections. In the transition zones between embayed to convex coastlines, neither depositional nor erosional processes predominate, creating a sediment balance and producing aggradational barriers. [ABSTRACT FROM AUTHOR]

High-frequency measurements of airflow from ultrasonic anemometers and time-averaged cup anemometer profiles were taken during an oblique alongshore sand-transporting event (6.7 m/s) over a vegetated foredune in May 2002 as part of a larger study on the sedimentary dynamics of a beach-dune complex in Greenwich Dunes, Prince Edward Island National Park, Canada. Local flow and sand transport pathways deviated significantly from the regional wind because of topographic steering of oblique alongshore airflow on the beach back toward the foredune in the backshore. Flow decelerated on the lower seaward slope of the foredune because of flow stagnation and vegetation-induced roughness effects. On the upper seaward slope, flow veered crest-parallel because of secondary flow effects, including potential flow reversal, acceleration, and interaction with faster regional flow. An inflection point in velocity profiles indicates a momentum sink at plant canopy height, and above this height exists a distinct shear layer. Flow acceleration occurs only on the upper slope above the plant canopy as the shear layer intensifies. Flow steadiness, as indicated by the coefficient of variation in horizontal (U) and vertical (W) velocity, also declines up the seaward slope, in contrast to measurements of flow over unvegetated dunes, perhaps because of increasing vegetation-induced drag and turbulence. Gusting and vertical bursting was evident as honami motion in the beachgrass and was responsible for maintaining intermittent saltation into the foredune. Temporal correlations exist between U, W, and flow angle. As flow shifted onshore, both U and W increased because of enhanced topographic forcing and increased vertical lift on the lower seaward slope, whereas when flow shifted alongshore, U and W declined because of reduced forcing and acceleration effects because the dune is effectively less steep to flow. Although these dunes align well with the vector of the regional resultant sediment drift potential, sand transport pathways followed local flow vectors of varying magnitude and direction. Offshore to oblique alongshore winds are typical of the summer wind regime, and, although frequently incompetent, they contribute to dune maintenance by cycling sand to the backshore for incipient foredune growth, scarp infilling, or both. To date, the role of secondary flows under alongshore winds in foredune morphodynamics has not been well documented. [ABSTRACT FROM AUTHOR]

Sediment transport across a foredune and beach at Ocean City, New Jersey, was examined to identify the effect of houses, dune topography, sand fences, vegetation, and wrack lines during an offshore wind. Houses are as close as 18 m from the crest of the 2- to 3-m-high foredune and are up to 9.0 m high and 12.8 m wide and spaced 4.0 to 5.0 m apart. Data were gathered during a 1-day study on 3 March 2003 with the use of 15 vertical sand traps, 13 erosion pins, and eight sets of anemometers placed 0.3, 0.6, and 0.9 m above the ground surface. Wind speeds 0.9 m above the ground ranged from 1.61 to 3.75 m/s. Trapping rates were negligible on the vegetated dune crest and up to 2.03 kg m-1 h-1 near mid foreshore. The highest rate of trapping was 2.4 kg m-1 h-1 at a <10-m-wide unvegetated area in the dune. Houses shelter the dune from offshore winds and might contribute to dune stability. Increases in wind speed in the offshore direction cause greater rates of transport on the seaward side of the dune where vegetation has not had time to become established. Dune vegetation, remnant sand fences, wrack lines, and the sheltered area in the lee of the seaward dune ridge can trap sediment moving offshore during relatively low wind speeds. Sediment deposited at these obstacles could contribute to deflation of the backshore, which is the primary source of sediment moved to the inter-tidal foreshore. Losses of sediment from unvegetated portions of the dune to the beach can be overcome by replacing sand fences and suspending beach raking until the calmer summer months. [ABSTRACT FROM AUTHOR]

This paper examines the behaviour of wind flow within a trough blowout on the Manawatu coastline, lower west coast, North Island, New Zealand. The trough blowout is 40 metres long, 20 metres wide and 7-8 metres deep. Virtually any wind flow approaching the blowout from a seaward, alongshore or slightly offshore direction in an arc of at least 200 degrees to the entrance orientation will be directed into the blowout. This happens for a number of reasons including (i) the relatively deep trough topography is an area of intense localised low pressure and winds are "sucked" into the blowout; (ii) topographic steering by the blowout erosional walls; (iii) local flow separation over the blowout wall crests and within the blowout during alongshore and offshore winds, and (iv) re-direction/deflection of low to moderate obliquity approach flows to seawards and over the foredune. This research indicates that winds from a wide range of approach directions will influence blowout flow, sand transport, erosion and deposition patterns, and evolution. It cannot be assumed that only "onshore" winds will transport sediment up a blowout. The implications for routine determination of sand transport by remote sensing in blowouts are significant. [ABSTRACT FROM AUTHOR]

The author shares his experiences which provided him the fortitude to survive the events that occurred when conducting rip experiments. He talks about the hurricanes and other disasters he encountered, an experiment he conducted as a part time research assistant working for L. Don Wright at Palm Beach in Sydney, New South Wales, and a large scale surf zone experiment organised by Rob Brander in New Zealand.

Moulton, M.A.B.; Hesp, P.A.; Miot da Silva, G.; Keane, R., and Fernandez, G.B., 2020. Effects of the increase in vegetation cover and impact of rabbits on the geomorphology of parabolic dunes (Younghusband Peninsula - SA, Australia). In: Malvárez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 108-112. Coconut Creek (Florida), ISSN 0749-0208. This study examines the geomorphological changes that occurred in a large parabolic dune on the Younghusband Peninsula (YP) dune system (South Australia) due to changes in vegetation cover in the past ∼70 years. Recent studies have shown that vegetation cover has significantly increased due to the control of exotic rabbits by introducing Myxomatosis (1950's) and Rabbit Haemorrhagic Disease Virus (1990's and 2000's). Using a sequence of historical aerial photographs between 1949 and 2018 and LiDAR data (2018), changes in the geomorphological evolution of a typical parabolic dune were analyzed. In 1949 a well-developed transgressive and parabolic dunefield connected to the beach was present. In 1975 (26 years later), the parabolic dune analyzed here experienced partial stabilization by the increase in vegetation cover on the deflation basin and on top of the depositional lobe, where nebkha dunes started to develop. Vegetation of the nebkha eventually connected to the vegetation of the deflation basin, separating the parabolic dune into two. In 2018, a major stabilization of parabolic dunes, now disconnected from the beach by high foredunes, together with an increase of vegetation in the nebkha fields, deflation basin and in the interdune depression were observed. Although a gradual reduction in bare sand area within the parabolic dune and deflation basin was observed, demonstrating a clear stabilization process in the period analyzed, a significant increase in dune migration rate was observed between 1984 and 1995 (9.6 m/y), with was only acceded by the initial period 1949-1956 (14.6 m/y). These two periods correspond to times when European rabbit populations were highest in the YP, suggesting that these exotic herbivores played a significant role in the geomorphological evolution of parabolic dunes. [ABSTRACT FROM AUTHOR]

Robin, N.; Billy, J.; Castelle, B.; Hesp, P.; Laporte-Fauret, Q.; Nicolae-Lerma, A.; Marieu, V.; Rosebery, D.; Bujan, S.; Destribats, B., and Michalet., 2020. Beach-dune recovery from the extreme 2013-2014 storms erosion at Truc Vert Beach, Southwest France: New insights from ground-penetrating radar. In: Malvárez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 588–592. Coconut Creek (Florida), ISSN 0749-0208. Foredunes are efficient natural coastal defenses acting as protective barriers during storm events. A striking example is the response of coastal dunes along the Aquitaine Coast (SW France) to the 2013-2014 winter, which was the most energetic winter since at least the mid-20th century in most of the NE Atlantic. The aim of this study is to analyze the (partial) foredune recovery from the 2013-2014 winter at Truc Vert beach using ground-penetrating radar (GPR) and through the coastal dune internal structure. Geophysical data was compared with semi-monthly DGPS topographic data of the beach, UAV-photogrammetry and Airborne LiDAR surveys of the coastal dune. Three main recovery phases were identified from the 2013-2014 winter: (i) aggradation of the upper-beach and dune front-crest during the post-storm summer; (ii) distinct phases of incipient dune-foot development with dune-crest stability during the following year, and (iii) since 2016, aggradation of both dune-foot and dune front-crest tending towards an equilibrium profile. This study shows that GPR surveys, combined with chronological topographic data, is an efficient tool to provide comprehensive understanding of the beach-dune system evolution at a decadal scale. This approach opens new perspectives to document foredune recovery timing and magnitude along sandy coasts. [ABSTRACT FROM AUTHOR]

A Holocene sea level curve for Singapore is presented. Radiocarbon dating of a variety of shell, wood, peat and coral material is utilised to derive the curve. Most of the dated material comes from a low energy, 'quietwater' estuarine environment. at Sungei Nipah, and the remainder from the tops of relict Porites coral bommies at Pulau Semakau. Determination of the curve takes into consideration the environmental factors and conditions that determined the elevation range of thematerial dated. The tentative results indicate that the Holocene Post-Glacial Marine Transgression reached present mean sea level around 6,500 to 7,000 years BP, rose to nearly 3 m above present, and began to fall to present MSL around 3000 or less years ago, A comparison ofthe proposed sea-level curve with the curve for Peninsular Malaysia indicates that the highest mid-Holocene sea level may have been closer to +3 m rather than +5 m. [ABSTRACT FROM AUTHOR]