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ABSTRACT Barboza, E.G.; Rosa, M.L.C.C.; Dillenburg, S.R.; Watanabe, D.S.Z.; Esteves, T.; Martins, E.M., and Gruber, N.L.S., 2018. Diachronic Condition Between Maximum Transgressive and Maximum Eustatic Sea-Level in Holocene: Subsidies for Coastal Management. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 446–450. Coconut Creek (Florida), ISSN 0749-0208. The coastline of Pelotas Basin/Brazil displays alternate sectors showing long-term conditions of erosion and accretion during the Holocene, corresponding to retrogradational/transgressive and progradational/regressive barriers respectively. Currently, the retrogradational/transgressive sectors are suffering from problems related to coastal erosion, generating problems for the public and private sectors. Thus, it is important to understand if coastal sectors suffer long-term erosion. The transition between a retrogradational/transgressive and a progradational/regressive barrier is still not well known, and this is the reason why some GPR (Ground Penetrating Radar) profiles and a drilling were performed in the transition region between the two basic types of barriers that occur at São José do Norte/RS/Brazil. Six radarfacies of aeolian, lagoon and backshore/foreshore, upper/lower shoreface deposits were identified, and, also, the subsurface transition, between a transgressive phase and a regressive phase of the barrier was identified. In the transition, reflectors of a paleochannel and a delta system were interpreted as corresponding to active channel systems during the last glaciation, which was then partially reworked during the final stages of the postglacial marine transgression. The barrier at São José do Norte changed from retrogradational/transgressive to a progradational/regressive phase before the maximum eustatic sea-level which occurred at about 5.6 ka, defining a diachronic condition of the maximum transgression identified in the GPR record and dated by 14C at 6,652 – 6,424 yr cal BP. Based on these results, the area is considered to have a long-term progradational behavior. The identification of deposits with conditions of erosion and accretion in the subsurface gives important information to the understanding of the coastal evolution of Pelotas Basin and contributing to coastal management by identifying the long-term behavior of this sector. [ABSTRACT FROM AUTHOR]

Barboza, E.G.; Rosa, M.L.C.C.; Dillenburg, S.R.; Watanabe, D.S.Z.; Esteves, T.; Martins, E.M., and Gruber, N.L.S., 2018. Diachronic Condition Between Maximum Transgressive and Maximum Eustatic Sea-Level in Holocene: Subsidies for Coastal Management. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 446–450. Coconut Creek (Florida), ISSN 0749-0208. The coastline of Pelotas Basin/Brazil displays alternate sectors showing long-term conditions of erosion and accretion during the Holocene, corresponding to retrogradational/transgressive and progradational/regressive barriers respectively. Currently, the retrogradational/transgressive sectors are suffering from problems related to coastal erosion, generating problems for the public and private sectors. Thus, it is important to understand if coastal sectors suffer long-term erosion. The transition between a retrogradational/transgressive and a progradational/regressive barrier is still not well known, and this is the reason why some GPR (Ground Penetrating Radar) profiles and a drilling were performed in the transition region between the two basic types of barriers that occur at São José do Norte/RS/Brazil. Six radarfacies of aeolian, lagoon and backshore/foreshore, upper/lower shoreface deposits were identified, and, also, the subsurface transition, between a transgressive phase and a regressive phase of the barrier was identified. In the transition, reflectors of a paleochannel and a delta system were interpreted as corresponding to active channel systems during the last glaciation, which was then partially reworked during the final stages of the postglacial marine transgression. The barrier at São José do Norte changed from retrogradational/transgressive to a progradational/regressive phase before the maximum eustatic sea-level which occurred at about 5.6 ka, defining a diachronic condition of the maximum transgression identified in the GPR record and dated by 14C at 6,652 – 6,424 yr cal BP. Based on these results, the area is considered to have a long-term progradational behavior. The identification of deposits with conditions of erosion and accretion in the subsurface gives important information to the understanding of the coastal evolution of Pelotas Basin and contributing to coastal management by identifying the long-term behavior of this sector. [ABSTRACT FROM AUTHOR]

Rosa, M.L.C.C; Barboza, E.G.; Menegon, B.S.; Frota, P.C.; and Anoni, R.A.O., 2016. Geological evolution and inundation hazard: an analysis through geotechnologies. 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. 1227 - 1231. Coconut Creek (Florida), ISSN 0749-0208. In the southern coastal plain of Rio Grande do Sul, southern Brazil, part of the city of Santa Vitória do Palmar was studied to analyze inundation hazard and its relation to geological evolution. Remote sensing, GNSS, total station surveys, laser scanning and photogrammetric reconstructions with a low cost UAV were combined and compared aiming at defining four main units with different levels of inundation susceptibility, which correspond to geological units of different ages. The allogenic factor related to the development of these units is sea level, which controls lagoon level, and determines that younger areas have higher inundation susceptibility. An autogenic control was also verified and is related to the dynamics of the lagoon system, where spits are higher and have a lower susceptibility when compared to the plains of the same age. [ABSTRACT FROM AUTHOR]

Barboza, E.G., Rosa, M.L.C.C., Dillenburg, S.R and Tomazelli, L.J., 2013. Preservation potential of foredunes in the stratigraphic record. In: Conley, D.C., Masselink, G., Russell, P.E. and O'Hare, T.J. (eds.) Foredunes occur worldwide on shorelines, especially those which are wave-dominated and with moderate to high sediment supply. Pelotas Basin, located in southern Brazil, has a significant record of foredunes which are present on modern beaches as well as in the geological record. Many locations along the Holocene coastal plain of Pelotas Basin were investigated with a Ground Penetrating Radar (GPR). Foredunes are present in almost all the investigated areas. However some peculiarities were found along these areas. At some places it is still possible to see foredune morphology in the field. At these places GPR profiles show a convex ridge morphology preserved and its separation by concave, sometimes filled swales. At other sites foredunes are covered by transgressive dunes, the morphology is not preserved and erosive surfaces are found on the top of the unit. Along the progradational sectors, dip profiles show that even where foredunes have their morphology preserved, some erosive scarps are found at the seaward face. These patterns indicate that high frequency events lead to the erosion of foredunes. The combination of sedimentary budget with climatic events sets foredune preservation and its pattern. Where sedimentary budget is high, progradation occurs faster and foredunes are preserved. However, where the sedimentary budget is not very expressive, the progradation is slower and part of the foredune is destroyed forming transgressive dunes or sand sheets. [ABSTRACT FROM AUTHOR]

The paper of Milana et al. (2016) presented interesting palaeoclimatic results related to the evolution of a foredune ridge plain of a regressive (prograded) barrier in southern Brazil. Unfortunately, they presented an evolutionary model for a type of wave-dominated delta, and not for a coastal barrier. By not classifying the regressive barrier of Cassino properly, the authors made a succession of incorrect interpretations, such as the nature of littoral drift directions during the progradation of the ridge plain. By using their delta model, they obtained opposite directions than the actual ones. In challenging the barrier model of the area, which has been well-established for more than 50 years, they should have more fully discussed the differences between deltas and barrier systems, in a manner which would have given support to their interpretations. [ABSTRACT FROM AUTHOR]

This paper presents the geological and morphological evolution of the prograded Cassino barrier during the middle and late Holocene. A special focus is given on the presentation and discussion of records of environmental changes that occurred during barrier progradation. The results demonstrated that variable rates of progradation were produced by environmental changes that affected the coastal sediment budget, such as changes in the wave climate. The total progradation of 18 km recorded for the Cassino barrier is probably the highest extension of progradation registered for a ridge plain associated with a coastal barrier. Sea-level changes during barrier progradation were accessed by the high difference between the degree of compaction of the foredune and backshore/foreshore deposits detected by the drilling system applied in this study and were confirmed by the limit of those deposits, which were also revealed by GPR records. During most of the time of barrier progradation, an overall sea-level fall of approximately 2 ± 1 m occurred. Six sets of relict foredune ridges were identified, and the limits between them were well marked by ridge truncations and the formation of transgressive dune sheets (TDS). Optically stimulated luminescence ages show that the TDS were formed under the driest climate conditions, with age periods very close to 3.8, 3.5, 1.9, 1.5, 0.22 and 0.09 ka ago, interspersed with ages of known wetter conditions in southern Brazil. The modern phases of TDS formation, with ages varying from 0.25 to 0.22 ka ago, were coincident with the time period of the younger pulse of the Little Ice Age (LIA), which was characterized by arid and cold conditions in southern South America. A comparison with prograded barriers located 350 to 600 km to the north suggests the existence of teleconnections, with phases of TDS and parabolic dunes that formed with a time interval of approximately 405 to 583 years. [ABSTRACT FROM AUTHOR]

Rockett, G.C.; Barboza, E.G., and Rosa, M.L.C.C. 2016. Ground Penetrating Radar applied to the characterization of the Itapeva Dunefield, Torres, 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. 323-327. Coconut Creek (Florida), ISSN 0749-0208. Subsurface data obtained from Ground Penetrating Radar (GPR) have been used in studies in various coastal plain environments. GPR applied to dune characterization and stratigraphy is well described in the literature, and enables the distinction between different depositional patterns and their delimitation. This study aimed to characterize the stratigraphy of the Itapeva dunefield, located at the municipality of Torres, north of the Rio Grande do Sul (Brasil) coastal plain, using subsurface data. This dunefield contains aeolian forms that differ from other dunefields in Rio Grande do Sul: namely, reversing dunes. The 150 and 400 MHz frequency antennas were used to collect subsurface data in dunes located in the central portion of the dunefield, with a linked GNSS system to obtain positional data. GPR data were processed, and the geospatial data were integrated to satellite images in a geographic information system. Results show that at least two different dune packages are present in the Itapeva dunefield, indicating two different depositional phases. [ABSTRACT FROM AUTHOR]

Biancini da Silva, A., Barboza, E.G., Rosa, M.L.C.C., Dillenburg, S.R., 2014. Meandering Fluvial System Influencing the Evolution of a Holocene Regressive Barrier in Southern Brazil. 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. 205-210, ISSN 0749-0208. A meandering fluvial system changes its course according to geological time, eroding rocks and pre-existing deposits and transporting large volumes of sediment to the coastal plains. Understanding the evolution of channels and paleochannels in regions showing coastal barriers and relating them to changes in sea level becomes extremely important to comprehend the factors that contribute to the behavior of coastal barriers. During the Holocene the barrier at Passo de Torres located northeast of the Mampituba River, along the southern coast of Santa Catarina state, prograded approximately 5.5 km. The barrier comprises both foredune ridges, which occur in the landward portion, and transgressive dune ridges, which occur seawards. One feature that stands out in the region is that the regressive barrier morphologies are truncated (eroded) by paleochannels and channels of a meandering fluvial system, which can be related to the dynamics of the Mampituba River. These paleochannels have elongated morphologies with SW - NE orientation and are up to 25 km long. With the purpose of characterizing the longer paleochannels, the geophysical method of ground penetrating radar (GPR) was used, associated with drill hole and radiocarbon dating. The GPR profile reveals continuous reflectors (± 5 m depth) with great contrast and lateral continuity for over 450 m. These represent an erosive surface, interpreted as the base of the fluvial channel. The granulometric results indicate that around 5 m, an increase in grain size (fine sand grading to medium sand) and the presence of several shells. These are very fragmented, characterizing a probable bedload transport. However, shells of the genus Donax sp. were collected intact with no signs of abrasion. This genus inhabits beach environments (specifically foreshore) and cannot survive in freshwater environments. These shells were incorporated to the bedload of the fluvial channel through an inlet, probably during storm surge events. These events carried beach sands, associated with shells (mainly Donax sp.), towards the continent, which were incorporated into the fluvial sediments. The dating of these species revealed an age between 5.6 - 5.4 cal ka. The ages obtained are consistent with the maximum sea level of the Postglacial Marine Transgression (PMT) in southern Brazil. Because these shells are exclusive to beach environments, dating allowed us to infer that this channel was active and had connection with the ocean at about 5.5 ka, concomitant with the maximum sea level of PMT. [ABSTRACT FROM AUTHOR]

This paper discusses a model of coastal barrier progradation where the development of a prograded plain was a product of the successive formation of foredune ridges followed by their burial by transgressive sand sheets and dunefields. The results are based on direct lithological data from drill holes and geomorphological analyses, indirect geophysical data (GPR), and 14C and OSL dating. Barrier progradation started at 6.69 ka (OSL) or 7.2 ka (14C), under sea-level rise. At around 5.0 ka (OSL), or thereabouts, a forced regression condition started to operate, when sea-level started to fall after it reached a maximum of 2.34 ± 0.8 m. During barrier progradation sets of foredunes were formed, and at least some of them were buried by sands of transgressive dunefields (TDF), which later evolved to transgressive sand sheets (TSS). A total of 11+ phases of TSS and a modern phase of TDF were formed in a time span of 6.69 ka (OSL) or 7.2 ka (14C), corresponding to one phase formed at each 560 or 600 yrs. Two models of possible development of the surface of Curumim barrier are proposed. • Arare record of aforedune plain buried by transgressive sandsheets formation. • The cyclic formation of transgressive dunefieldsand transgressive sand sheets. • The foredune/beach contact as a proxy of sea-level position. • Distinct contributions of normal and forced regressionon barrier progradation. • Possibletransformation of a transgressive dunefield in a transgressive sand sheet. [ABSTRACT FROM AUTHOR]

Dillenburg, S.R.; Barboza, E.G.; Rosa, M.L.C.C.; Caron, F., and Bitencourt, V.B., 2020. Changes in the littoral drift of the Uruguayan coast during the Holocene and its influence in the continuing erosion in southern Brazil. In: Malvárez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 453–457. Coconut Creek (Florida), ISSN 0749-0208. In northern Uruguay and southern Brazil, a littoral drift system dominates from southwest to northeast. This littoral drift is a consequence of higher wave-energy, generated in southern latitudes and that has been operating on a long-term scale, playing an important role not only in the evolution of coastal barriers of this region during the Holocene but also in coastal erosion that presently occurs in some parts of this coast. From La Coronilla to Cabo Santa Marta, which is a coastal sector 750 km - along the coast is gently undulating, showing gentle projections located to the south of gentle reentrances, that are dominated by transgressive/stationary and regressive barriers, respectively. In general, the regressive barriers have been developed by sediments brought into the reentrances by long-shore currents. The main source of these sediments had been the transgressive/stationary barriers that occur along the coastal projections. This differentiation of barrier behavior started at around 6-5 ka, at the end of the Postglacial Marine Transgression (PMT), when all rivers were drowned, finishing the delivery of new coarse sediments to the coast. Also, at this time the large rock promontories of the Uruguayan coast were formed and started to retain sediments of the littoral drift system, triggering a long-term coastal erosion in the southernmost coastal projection. Regarding erosion that is occurring in this stretch of coast the important issue to be considered in future coastal planning is that erosion will continue to operate in the long-term but will also be (and certainly has been already) amplified by sea-level rise in the next centuries as projected by the Intergovernmental Panel on Climate Change (IPCC). [ABSTRACT FROM AUTHOR]

Scarelli, F.M.; Cantelli, L.; Barboza, E.G.; Rosa, M.L.C.C.; and Gabbianelli, G., 2016. Natural and Anthropogenic coastal system comparison using DSM from a low cost UAV survey (Capão Novo, RS/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. 1232 - 1236, ISSN 0749-0208. In many cases, unplanned urbanization is the main factor that causes a decrease in coastal resilience. This paper compares the differences between the anthropogenic and natural coastal zone, based on the morphological dune reconstruction, using a low cost UAV (unmanned aerial vehicle) survey and the photogrammetric reconstruction method. The study area is in the Northern Littoral of Rio Grande do Sul State, where the dunes have few man-changes and are adjacent to an anthropogenic zone with a highly modified beach/dune system. By photogrammetric reconstruction it was possible to obtain a high-resolution DSM (Digital Surface Model) and a high-resolution othophoto to analyse differences in morphology. Data acquired by UAV's are important to coastal managers and decision makers as they can collect high-resolution data and be used for Integrated Coastal Zone Management. Moreover this work propose a low cost method for obtaining a high-resolution data for researchers and local authorities. [ABSTRACT FROM AUTHOR]

This paper describes the evolution of a sector of the southern coastal plain of the Pelotas Basin, southern Brazil, between the last Pleistocene sea-level lowstand and the Holocene highstand, based on geomorphology and high-resolution stratigraphy. A fluvial drainage system associated with an incised valley developed during the Last Glacial Maximum (LGM) was identified. Two high-resolution 2D and 2.5D geophysical profiles using Ground-Penetrating Radar (GPR) show a Pleistocene fluvial system's former path, starting close to its present mouth inside Mirim Lagoon crossing the coastal barriers and reaching the inner continental shelf, covering some 60 km across the coastal plain. During the LGM, with the sea-level at −120 to −130 m and the coastline positioned close to the shelf edge (distant 200 km from the present coastline), the fluvial system excavated a ~31.5-m deep channel. Two cores, 36 and 32 m long, show that the paleochannel was filled with sedimentary deposits after 19.4 ka BP, and the facies succession represents the transition from fluvial, to estuarine, to the coastal barrier, and finally to inner shelf depositional environments, generated by processes connected to LGM and the Postglacial Marine Transgression (PMT). The study region behaved as a sediment by-pass zone, connecting the adjacent coastal plain's inner portion with the inner continental shelf. The studied area presents an unusual record of the LGM at a coastal plain domain. [Display omitted] • Records of the Last Glacial Maximum on the coastal plain. • Coastal stratigraphy transition: from basal fluvial to coastal barrier deposits. • Integrating GPR records and Drill Holes data on coastal evolution investigation. • Seismic facies and radarfacies as proxies for coastal evolution. • First record of continuous paleochannel in Southern Brazil. [ABSTRACT FROM AUTHOR]