Response of Reed Mudflats in the Caspian Coastal Zone to Sea Level Fluctuations

2008 ◽  
pp. 439-460
Author(s):  
Valentina I. Kravtsova
Keyword(s):  
Sea Level ◽  
Coastal Zone ◽  
Sea Level Fluctuations

ACCUMULATIVE COASTS AS RELIABLE INDICATORS OF THE KINEMATICS OF THE SEA LEVEL DURING THE HOLOCENE

2017 ◽  
Author(s):  
Nikolay Dunaev ◽  
Nikolay Dunaev ◽  
Tatiana Repkina ◽  
Tatiana Repkina
Keyword(s):  
Sea Level ◽  
Coastal Zone ◽  
Synoptic Scale ◽  
The Holocene ◽  
Single View ◽  
Sea Level Fluctuations ◽  
Current State ◽  
Geological Section ◽  
Global Sea Level ◽  
Different Parts

Currently, there is no single view of the Holocene global sea level kinematics. At the same time, the question of a possibility of it exceeding the current sea level by several meters is be-ing debated. The accumulative coasts of nearly tide-free seas, in areas where the vertical di-rection of coastal movement remained unchanged are the most convenient objects for study-ing this major paleogeographic issue. Effects of the sea level fluctuations are revealed in the resulting geomorphological structure and in the nature of sediment areas of the coastal zone developing in an accumulative mode. If the Holocene sea level exceeds its modern marks, then ladders of accumulative terraces would have formed over different parts of the coast. The heights of the terrace ladders would correspond to the amplitudes of these exceedances. The lower sediment levels should reflect the transgressive character of their formation in the structure of geological section, while the higher levels would reflect the regressions. The coast of the Thatcher Peninsula, located in the Bay of Cumberland microcontinent of the South Georgia (Antarctic) was the focus of our research. It was established that the Holo-cene sea level in the region reached its current state no later than about one thousand years ago and did not exceed it, being subjected to only minor fluctuations of the synoptic scale. The accumulative terraces are located in fragments. The differences in their absolute eleva-tions are related to their correspondence to different tectonic units experiencing differenti-ated uplift.

ACCUMULATIVE COASTS AS RELIABLE INDICATORS OF THE KINEMATICS OF THE SEA LEVEL DURING THE HOLOCENE

2017 ◽  
Author(s):  
Nikolay Dunaev ◽  
Nikolay Dunaev ◽  
Tatiana Repkina ◽  
Tatiana Repkina
Keyword(s):  
Sea Level ◽  
Coastal Zone ◽  
Synoptic Scale ◽  
The Holocene ◽  
Single View ◽  
Sea Level Fluctuations ◽  
Current State ◽  
Geological Section ◽  
Global Sea Level ◽  
Different Parts

Currently, there is no single view of the Holocene global sea level kinematics. At the same time, the question of a possibility of it exceeding the current sea level by several meters is be-ing debated. The accumulative coasts of nearly tide-free seas, in areas where the vertical di-rection of coastal movement remained unchanged are the most convenient objects for study-ing this major paleogeographic issue. Effects of the sea level fluctuations are revealed in the resulting geomorphological structure and in the nature of sediment areas of the coastal zone developing in an accumulative mode. If the Holocene sea level exceeds its modern marks, then ladders of accumulative terraces would have formed over different parts of the coast. The heights of the terrace ladders would correspond to the amplitudes of these exceedances. The lower sediment levels should reflect the transgressive character of their formation in the structure of geological section, while the higher levels would reflect the regressions. The coast of the Thatcher Peninsula, located in the Bay of Cumberland microcontinent of the South Georgia (Antarctic) was the focus of our research. It was established that the Holo-cene sea level in the region reached its current state no later than about one thousand years ago and did not exceed it, being subjected to only minor fluctuations of the synoptic scale. The accumulative terraces are located in fragments. The differences in their absolute eleva-tions are related to their correspondence to different tectonic units experiencing differenti-ated uplift.

scholarly journals Spatial distribution of water level impact to back-barrier bays

2018 ◽  
Author(s):  
Alfredo L. Aretxabaleta ◽  
Neil K. Ganju ◽  
Zafer Defne ◽  
Richard P. Signell
Keyword(s):  
Water Level ◽  
Sea Level ◽  
Water Levels ◽  
Analytical Models ◽  
Barnegat Bay ◽  
Sea Level Fluctuations ◽  
Flooding Hazard ◽  
Short Period ◽  
Inlet Geometry ◽  
Spatial Estimates

Abstract. Water level in semi-enclosed bays, landward of barrier islands, is mainly driven by offshore sea level fluctuations that are modulated by bay geometry and bathymetry, causing spatial variability in the ensuing response (transfer). Local wind setup can have a secondary role that depends on wind speed, fetch, and relative orientation of the wind direction and the bay. Inlet geometry and bathymetry primarily regulate the magnitude of the transfer between open ocean and bay. Tides and short-period offshore oscillations are more damped in the bays than longer-lasting offshore fluctuations, such as storm surge and sea level rise. We compare observed and modeled water levels at stations in a mid-Atlantic bay (Barnegat Bay) with offshore water level proxies. Observed water levels in Barnegat Bay are compared and combined with model results from the Coupled Ocean–Atmosphere–Wave–Sediment Transport (COAWST) modeling system to evaluate the spatial structure of the water level transfer. Analytical models based on the dimensional characteristics of the bay are used to combine the observed data and the numerical model results in a physically consistent approach. Model water level transfers match observed values at locations inside the Bay in the storm frequency band (transfers ranging from 70–100 %) and tidal frequencies (10–55 %). The contribution of frequency-dependent local setup caused by wind acting along the bay is also considered. The approach provides transfer estimates for locations inside the Bay where observations were not available resulting in a complete spatial characterization. The approach allows for the study of the Bay response to alternative forcing scenarios (landscape changes, future storms, and rising sea level). Detailed spatial estimates of water level transfer can inform decisions on inlet management and contribute to the assessment of current and future flooding hazard in back-barrier bays and along mainland shorelines.

BIOINDICATORS OF SEA-LEVEL FLUCTUATIONS IN SOUTHEASTERN BRAZIL: NEW DATA AND METHODOLOGICAL REVIEW

Radiocarbon ◽  
2021 ◽  
pp. 1-15
Author(s):  
Julia Caon Araujo ◽  
Kita Chaves Damasio Macario ◽  
Vinícius Nunes Moreira ◽  
Anderson dos Santos Passos ◽  
Perla Baptista de Jesus ◽  
...  
Keyword(s):  
Sea Level ◽  
Late Holocene ◽  
Data Interpretation ◽  
Progressive Increase ◽  
Southeastern Brazil ◽  
Recrystallization Process ◽  
Sea Level Changes ◽  
Sea Level Fluctuations ◽  
Data Gap ◽  
Current Zero

ABSTRACT The vermetidae fossils of Petaloconchus varians, formed by calcium carbonate, associated with their radiocarbon ages, are the most accurate indicators of paleo sea level due to their restricted occupation in the intertidal zone in the rocky shore. However, the recrystallization of minerals can affect these age calculations and, consequently, the interpretation of the data. The aim of this study is to present new indicators of paleo sea-level changes in Southeast Brazil for the last 6000 years contributing to fill the data gap for the late Holocene. The influence of the recrystallization process was successfully resolved using the CarDS protocol, enabling the separation of the original aragonite fraction by density, prior to radiocarbon dating. This avoids the rejuvenation of ages and ensures greater efficiency for data interpretation. Paleo sea-level indicators were able to show a progressive increase in sea level up to the transgressive maximum of 4.15 m in 3700 BP years, followed by a regression to the current zero. This regression seems to have in addition, here we reinforce the reliability of the use of fossil vermetids as indicators of sea-level fluctuations.

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