A diachronic view of the net longshore sediment drift during the Late Holocene at the Jequitinhonha River delta, Brazil, using numerical modeling

Using numerical modeling, this work estimates sediment dispersion patterns caused by the incidence of waves in five distinct coastline contours of the Jequitinhonha River delta plain during the Late Holocene. For this study, a wave cliate odel based on the construction of ave refraction diagras relative to the current boundary conditions as defined and assumed to be valid for the five coastlines. Numerical modeling from the refraction diagrams was carried out considering the angle of incidence and wave height along the coastline. This work has allowed us to reproduce past and current patterns of net longshore sediment drift defined by a conceptual model developed from the integration of sediment cores, aerial photograph interpretation, C14 datings and geomorphic indicators of longshore drift. These results show that, on average, current wave conditions in the east-northeastern Brazilian region seem to have remained characteristically the same from approximately 5100 years BP until the present time. This type of information can be important when attempting to simulate possible future situations in terms of the long-term general behavior of the east-northeastern Brazilian coastal region.

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Cryostratigraphy, sedimentology, and the late Quaternary evolution of the Zackenberg River delta, northeast Greenland

The Cryosphere ◽

10.5194/tc-11-1265-2017 ◽

2017 ◽

Vol 11 (3) ◽

pp. 1265-1282 ◽

Cited By ~ 14

Author(s):

Graham L. Gilbert ◽

Stefanie Cable ◽

Christine Thiel ◽

Hanne H. Christiansen ◽

Bo Elberling

Keyword(s):

Late Quaternary ◽

Sediment Cores ◽

River Delta ◽

Optically Stimulated Luminescence ◽

Delta Plain ◽

Valley Fill ◽

Subaerial Exposure ◽

Facies Associations ◽

Delta Progradation ◽

Ice Content

Abstract. The Zackenberg River delta is located in northeast Greenland (74°30′ N, 20°30′ E) at the outlet of the Zackenberg fjord valley. The fjord-valley fill consists of a series of terraced deltaic deposits (ca. 2 km2) formed during relative sea-level (RSL) fall. We investigated the deposits using sedimentological and cryostratigraphic techniques together with optically stimulated luminescence (OSL) dating. We identify four facies associations in sections (4 to 22 m in height) exposed along the modern Zackenberg River and coast. Facies associations relate to (I) overriding glaciers, (II) retreating glaciers and quiescent glaciomarine conditions, (III) delta progradation in a fjord valley, and (IV) fluvial activity and niveo-aeolian processes. Pore, layered, and suspended cryofacies are identified in two 20 m deep ice-bonded sediment cores. The cryofacies distribution, together with low overall ground-ice content, indicates that permafrost is predominately epigenetic in these deposits. Fourteen OSL ages constrain the deposition of the cored deposits to between approximately 13 and 11 ka, immediately following deglaciation. The timing of permafrost aggradation was closely related to delta progradation and began following the subaerial exposure of the delta plain (ca. 11 ka). Our results reveal information concerning the interplay between deglaciation, RSL change, sedimentation, permafrost aggradation, and the timing of these events. These findings have implications for the timing and mode of permafrost aggradation in other fjord valleys in northeast Greenland.

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Past and current sediment dispersion pattern estimates through numerical modeling of wave climate: an example of the Holocene delta of the Doce River, Espírito Santo, Brazil

Anais da Academia Brasileira de Ciências ◽

10.1590/s0001-37652007000200014 ◽

2007 ◽

Vol 79 (2) ◽

pp. 333-341 ◽

Cited By ~ 9

Author(s):

Abílio C.S.P. Bittencourt ◽

José M.L. Dominguez ◽

Louis Martin ◽

Iracema R. Silva ◽

Karla O.P. de-Medeiros

Keyword(s):

Numerical Modeling ◽

Boundary Conditions ◽

Late Holocene ◽

Climate Model ◽

Coastal Region ◽

Wave Climate ◽

Aerial Photographs ◽

Dispersion Pattern ◽

Dispersion Patterns ◽

Doce River

This paper presents a numerical modeling estimation of the sediment dispersion patterns caused by waves inciding through four distinct coastline contours of the delta plain of the Doce River during the Late Holocene. For this, a wave climate model based on the construction of wave refraction diagrams, as a function of current boundary conditions, was defined and was assumed to be valid for the four coastlines. The numerical modeling was carried out on basis of the refraction diagrams, taking into account the angle of approximation and the wave height along the coastline. The results are shown to be comparable with existing data regarding the directions of net longshore drift of sediments estimated from the integration of sediment cores, interpretation of aerial photographs and C14 datings. This fact apparently suggests that, on average, current boundary conditions appear to have remained with the same general characteristics since 5600 cal yr BP to the present. The used approach may prove useful to evaluate the sediment dispersion patterns during the Late Holocene in the Brazilian east-northeast coastal region.

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Late Holocene evolution of the Parnaíba River Delta (Brazilian Equatorial Margin): Evidence of lobe switching process from mineralogical analysis and age dating on sediment cores

Journal of South American Earth Sciences ◽

10.1016/j.jsames.2021.103530 ◽

2021 ◽

pp. 103530

Author(s):

Fernando Sérgio Gois Smith ◽

Helenice Vital ◽

Andre Giskard Aquino da Silva ◽

Karl Stattegger ◽

Yoe Alain Reyes Perez

Keyword(s):

Late Holocene ◽

Sediment Cores ◽

River Delta ◽

Switching Process ◽

Age Dating ◽

Mineralogical Analysis

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THE RESPONSE OF A COASTAL REGION WITH IRREGULAR REEF BATHYMETRY TO STRONG GRAVITY WAVE FORCING - A NUMERICAL MODELING STUDY

10.1130/abs/2017cd-292612 ◽

2017 ◽

Author(s):

Assaf Azouri ◽

◽

Douglas S. Luther ◽

Volker Roeber

Keyword(s):

Numerical Modeling ◽

Gravity Wave ◽

Coastal Region ◽

Strong Gravity ◽

Wave Forcing ◽

Modeling Study

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The Tiber river delta plain (central Italy): Coastal evolution and implications for the ancient Ostia Roman settlement

The Holocene ◽

10.1177/0959683611400464 ◽

2011 ◽

Vol 21 (7) ◽

pp. 1105-1116 ◽

Cited By ~ 63

Author(s):

P. Bellotti ◽

G. Calderoni ◽

F. Di Rita ◽

M. D’Orefice ◽

C. D’Amico ◽

...

Keyword(s):

Central Italy ◽

River Mouth ◽

Fourth Century ◽

River Delta ◽

Seventh Century ◽

Delta Plain ◽

Tiber River ◽

Military Posts ◽

Historical Accounts ◽

The Town

Geomorphologic, stratigraphic, faunistic, palynological and carbon isotope analyses were carried out in the area of the Tiber river mouth. The results depict a complex palaeoenvironmental evolution in the area of the Roman town of Ostia, ascertain the changes of the Tiber river delta over the last 6000 years and support a re-interpretation of some archaeologic issues. The wave-dominated Tiber delta evolved through three distinct phases. In the first step (5000–2700 yr BP) a delta cusp was built at the river mouth, which was located north of the present outlet. Subsequently (2700–1900 BP), an abrupt southward migration of the river mouth determined the abandonment of the previous cusp and the progradation of a new one. The third step, which is still in progress, is marked by the appearance of a complex cusp made up of two distributary channels. The transition from the first to the second evolution phase occurred in the seventh century bc and was contemporary to the foundation of Ostia, as suggested by historical accounts. However, the oldest archaeological evidence of the town of Ostia dates to the fourth century bc, when human activity is clearly recorded also by pollen data. We suggest that the first human settlement (seventh century bc) consisted of ephemeral military posts, with the aim of controlling the strategic river mouth and establishing the Ostia saltworks. Only after the fourth century bc the coastal environment was stable enough for the foundation and development of the town of Ostia.

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Vulnerability of the North Water ecosystem to climate change

Nature Communications ◽

10.1038/s41467-021-24742-0 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Sofia Ribeiro ◽

Audrey Limoges ◽

Guillaume Massé ◽

Kasper L. Johansen ◽

William Colgan ◽

...

Keyword(s):

Climate Change ◽

Sea Ice ◽

Late Holocene ◽

Sediment Cores ◽

Arctic Ecosystems ◽

Little Auk ◽

The North ◽

Water Ecosystem ◽

North Water

AbstractHigh Arctic ecosystems and Indigenous livelihoods are tightly linked and exposed to climate change, yet assessing their sensitivity requires a long-term perspective. Here, we assess the vulnerability of the North Water polynya, a unique seaice ecosystem that sustains the world’s northernmost Inuit communities and several keystone Arctic species. We reconstruct mid-to-late Holocene changes in sea ice, marine primary production, and little auk colony dynamics through multi-proxy analysis of marine and lake sediment cores. Our results suggest a productive ecosystem by 4400–4200 cal yrs b2k coincident with the arrival of the first humans in Greenland. Climate forcing during the late Holocene, leading to periods of polynya instability and marine productivity decline, is strikingly coeval with the human abandonment of Greenland from c. 2200–1200 cal yrs b2k. Our long-term perspective highlights the future decline of the North Water ecosystem, due to climate warming and changing sea-ice conditions, as an important climate change risk.

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Assessing ice margin fluctuations on differing timescales: Chronological constraints from Sermeq Kujatdleq and Nordenskiöld Gletscher, central West Greenland

The Holocene ◽

10.1177/0959683618761541 ◽

2018 ◽

Vol 28 (7) ◽

pp. 1160-1172 ◽

Cited By ~ 2

Author(s):

Samuel E Kelley ◽

Jason P Briner ◽

Sandy L O’Hara

Keyword(s):

Late Holocene ◽

Sediment Cores ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Ice Dynamics ◽

West Greenland ◽

Southern Site ◽

Ice Velocity ◽

Observational Record ◽

Local Variability

The observational record of ice margin position reveals asynchrony in both the timing and magnitude of Greenland Ice Sheet (GrIS) margin fluctuations and illustrates the complex reactions of ice sheets to climatic perturbations. In this study, we reconstruct the timing and pattern of middle- and late-Holocene GrIS margin fluctuations at two locations, ~190 km apart, in central West Greenland using radiocarbon-dated sediment cores from proglacial-threshold lakes. Our results demonstrate that deglaciation occurs at both sites during the early Holocene, with the ice sheet remaining in a smaller-than-present ice margin configuration until ~500 years ago when it readvanced into lake catchments at both sites. At our northern site, Sermeq Kujatdleq, the late-Holocene advance of the GrIS approached maximum position during the past 280 years, with the culmination of the advance occurring at AD 1992–1994, and modern retreat was underway by AD 1998–2001. In contrast, field and observational evidence suggest that the GrIS at our southern site, Nordenskiöld Gletscher, has been advancing or stable throughout the 20th century. These results, in conjunction with previous work in the region, highlight the asynchronous nature of late-Holocene advances and subsequent modern retreat, implying that local variability, such as ice velocity or ice dynamics, is responsible for modulating ice margin response to changes in climate on these decadal to centennial timescales. Additional high-resolution records of past ice sheet fluctuations are needed to inform and more accurately constrain our predictions of future cryosphere response to changes in climate.

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