Caspian Sea Level Fluctuations Research Articles

Dating the middle and late Quaternary Caspian Sea-level fluctuations: First luminescence data from the coast of Turkmenistan

The Caspian region provides the basis of the stratigraphy and palaeogeography of the Pleistocene of Central Eurasia, and has been actively studied for more than 200 years. Many issues concerning the palaeogeographic history of the various basins of Caspian Quaternary remain unsolved, but the main problem centres on uncertainties in the chronology. Previous chronological studies have focused on a detailed description of the sedimentation history in the Lower Volga and Eastern Caucasus, ignoring a number of unique sites on the eastern Caspian coast, mainly due to inaccessibility. We obtained access to one of the most complete sections, western Cheleken, located on the Caspian coast of Turkmenistan. Within this sandy and generally lowland coast, the western part of the Cheleken peninsula forms a 10 km wide cliff opening a unique series of Middle Pleistocene - Holocene sediments which record in detail the history of Caspian transgressions and regressions. Stratigraphical, geomorphological and palaeontological studies of the section were supplemented with luminescence and radiocarbon dating. Analysis of Caspian molluscs and luminescence ages allowed the reconstruction of the sedimentary history of this region during one of the most important events of the Caspian Basin: the Early and Late Khazarian, Khvalynian and Novocaspian transgression/regression series. Luminescence dating of quartz and feldspar provided 12 OSL, IR50 and pIRIR290 ages, comparison of which showed that quartz grains were sufficiently bleached before deposition. Our chronology provides, for the first time, a deeper understanding of the sedimentation and environmental history in this region and the entire Caspian Sea. The Early Khazarian transgression occurred here at ∼220–200 ka (MIS 7). The Late Khazarian stage recorded in shallow-marine clays had relatively stable level ∼150–130 ka ago. In the second half of MIS 5 sea-level decreased and sedimentation was controlled by a large river, most probably the palaeo-Amu-Daria. The Early Khvalynian stage started at ∼27 ka and continued presumably until ∼14 ka.

Changes in the Hydrological Regime of the Volga River and Their Influence on Caspian Sea Level Fluctuations

Changes in the Hydrological Regime of the Volga River and Their Influence on Caspian Sea Level Fluctuations

The influence of the Caspian Sea level fluctuations and river channels network dynamics in the Volga River delta on the location and development of Khazar settlements of the Semibugorinsky archaeological complex

The results of the comprehensive studies of ​​the Semibugorinsky archaeological complex in the central part of the Volga River delta make it possible to reconstruct the influence of the fluctuations of the Caspian Sea level and the dynamics of the channel network at the development of Khazar settlements in the 6th-10th centuries. During the period of the Caspian Sea level rise (-24 m abs.), part of the population, presumably, moved to the Baer knolls, which at that time became islands. The Volga River delta was located at the higher levels, which could lead to the resettlement of the part of the population to its northern periphery.

Geographic and geomorphologic context of Caspian Sea level fluctuations over the Late Pleistocene and Holocene

Geographic and geomorphologic context of Caspian Sea level fluctuations over the Late Pleistocene and Holocene

Late Holocene Vegetation and Environmental Changes of Coastal Lowlands in Northern Iran: Possible Role of Climate, Human Impact and Caspian Sea Level Fluctuations

Coastal forests and wetlands play an important role in supporting biodiversity, protecting the hinterlands and shorelines from erosion and also contributing to carbon sequestration and freshwater storage. To reconstruct late Holocene vegetation and environmental dynamics in the coastal lowlands of northern Iran and to detect the possible role of climate, human and Caspian Sea level fluctuation on coastal ecosystems, multi-proxy analysis was applied on the sediment cores from the inland Eynak (EYK) lagoon and near coast Bibi Heybat (BBH) alder swamp. Results shows that in the last 170 years, strong reduction of alder forest occurred around Eynak lagoon, while an expansion occurred in the coastal area in the last 100 years. This indicates that human impact shifted from the near coast to elevated inland, which might be due to the raised water level from the Caspian Sea and the coastal area of BBH region was flooded by brackish water from the Caspian Sea, and was not so suitable for agriculture anymore. This study indicate that alder swamp extent is different between coastal and inland sites, suggesting that further studies of multiple records across the region are needed. Moreover, this study helps to distangle human impacts from wetland processes and thus will be an important contribution to effective climate mitigation and conservation strategies. This multi-proxy study presents important palynological records, which helps to understand past and future impacts of various drivers, such as climate, human impact and sea level changes on wetland ecosystems both regionally and globally.

Geochemistry and ecological risk assessment of the coastal Tajan River using sediment quality indices (Southern Caspian Sea, Iran)

The present study aimed to reveal correlations between environmental events and geochemistry variation and ecological risks of the coastal Tajan River. Sediment quality indices (Cf, Cd, Er, and RI) were applied to achieve the research objectives based on the concentration of toxic metals (As, Cd, Cr, Cu, Ni, Pb, Zn). The probably effective level is based on the concentration of As, Cr, and Ni observed. The coastal zone and the urban sector of the river have experienced a moderate ecological risk since 1975, especially during wet seasons (1988–1997) with a mean sedimentation rate of 2 cm/year. A significant correlation (r=0.439–0.633, p-values < 0.0001) between the toxic metal concentration and the Caspian Sea level fluctuation was obtained. The lowest concentration of toxic metals coincided with the high stand water level. Management practices recommend controlling toxic metals (As, Cd, Ni, Cr, Pb) from the sources and dredging of retention pounds along the Tajan River.

LONG-TERM PREDICTION OF CASPIAN SEA LEVEL UNDER CMIP6 SCENARIOS USING ARTIFICIAL NEURAL NETWORKS

Artificial Neural Network (ANN) is employed to predict the long-term Caspian Sea level (CSL). 114-year observed CSL data (1900-2014) and the precipitation and temperature of historical and future scenarios of Coupled Model Intercomparison Phase 6 (CMIP6) are used to predict the future fluctuations of CSL (2015-2050). The values of the statistical indices in training, validating and testing periods (1900-2014) indicate the efficiency of the ANN in reconstruction of the CSL. Considering the outputs of different climate change projections (CMIP6) and excluding the human interventions, the study predicts the CSL fluctuation range of -28 m to -26m until 2050.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/Kfj-gr65TR8

Динамика каспийских берегов в концепции “АТласа культурного и природного наследия Дагестана”

Atlas of the cultural and natural heritage of Dagestan is a comprehensive cartographic work, which displays objects of archeology, history, ethnography, socio-economic sphere and nature, cultural, historical and natural heritage. The development of the Atlas is based on previously acquired experience in creating the Geographic and other atlases of Dagestan and involves the use of a number of methodological innovations, one of which is the use of typical contour maps with different physical and geographical outlines of coastal territories in specific historical eras. We are talking primarily about the coastline of the Caspian Sea, which has noticeably changed in the historical timescale. This approach allows to map the main historical milestones of the interaction of resettlement systems and households of the inhabitants of the Mountain Country with a very dynamic natural environment of this region. So, archaeological maps revealing the sites of pre-historic humans within the modern borders of the Republic of Dagestan include the lines of the Caspian coast in the ancient periods of sea transgressions and regressions. The atlas includes maps showing information on the dynamics and evolution of the Caspian coast for different historical eras as a result of sea level fluctuations and the variability of the Dagestan hydrographic network and the dynamics of the Terek delta and the mouth of Sulak. The history of the Caspian Sea level fluctuations was reconstructed starting from the regressive phase of sea level stand during pre-Bakinian time, when sufficiently reliable geological and geomorphological data were available to estimate, the amplitude and age of level changes. The Bakinian transgression, which consisted of two stages: Early Bakinian and Late Bakinian took place in the beginning of the Brunnes Era. Even more data is available for reconstruction of Early and Late Khazarian, and subsequent transgressions and regressions of the Caspian Sea, the boundaries of which are reflected on the map of the Paleolithic Era. The Atlas is divided into two parts, the first is represented by historical and cultural maps, the second – by the maps on natural and economic heritage of the Mountain Country. The introductory section includes basic maps on physical geography, the modern administrative-territorial division of Dagestan and its position in the North Caucasus Federal District. In total and in accordance with the work plan, the Atlas includes 100 major maps and more than 30 inset maps. A total of about 50 scientists and practitioners with different scientific profiles from the Dagestan Federal Research Center of the Russian Academy of Sciences institutes, Makhachkala universities, and Lomonosov Moscow State University took part in this work.

To the methods of geomorphological research (geomorphological lessons of the Caspian)

The main focus of the article is the significance of the geomorphological method for the reconstruction of paleogeographic events that took place in the Late Pleistocene and Holocene. The specific data obtained as a result of applying this method are given. A reasonable curve of the Caspian Sea level fluctuations in the Holocene was compiled. A risk zone has been defined, within which the level of the Caspian Sea will fluctuate in the future, under modern physics-geographical conditions, which is fundamental importance when planning any economic measures in the coastal zone. Predictions were made and later justified of the Caspian Sea level fluctuations in the 20thearly 21st centuries. The climatic nature of the Caspian transgressions was confirmed. Obtained were new data on the evolution of the shores of the Caspian Sea under rising level conditions, which can be used when forecasting the development of the shores of other seas in the conditions of the present-day rise of the World Ocean level.

Gorgan Bay environmental consequences due to the Caspian Sea rapid water level change

The rapid Caspian Sea level fluctuations have caused unstable conditions for coastal areas during the 20st and 21st centuries, and have led to significant losses for economical and social infrastructure. The main objective of this study was to assess the impact of the Caspian Sea level fluctuations on the environment of the Gorgan Bay coasts, which is a large, shallow inlet at the extreme south-east corner of the Caspian Sea. So that, studying required documentations have made it possible to become acquainted with the geographical, geological and environmental conditions of Gorgan Bay. The morphological conditions of coastal lines and diversity of coastal habitats were also assessed in field observations. The geometric structure of coast, their sediment types and the physicochemical properties of soils belonging to coastal habitats were evaluated by determining three transects and nine study sites in the spring and summer 2017. Changes in the coastline of Gorgan Bay were also processed using Land-Sat satellite imagery from 1977, 1995 and 2017. The results exhibited that the environmental vulnerability of the Gorgan Bay coasts depends on the morphological conditions of coastal habitats and alterations in the Caspian Sea level. So that, the plant and animal communities located in the most end of western part of the Gorgan Bay have faced serious challenges during the current century due to the decrease in the Caspian Sea level. Connecting canals between the Bay and Sea will also lose their discharge capacity and the Gorgan Bay will completely be dried up due to this decline. Emergence of large mudflats with sedimentary composition of sandy silt, which has created a very good potential for occurrence of haze, and also replacing the drought ecosystem, instead of the aquatic one, are other environmental events which are expanding vastly in the coastal areas of the Gorgan Bay.

Investigation of Caspian Sea Level Fluctuations Based on ECMWF Satellite Imaging Models and Rivers Discharge

Investigation of Caspian Sea Level Fluctuations Based on ECMWF Satellite Imaging Models and Rivers Discharge

CASPIAN SEA GEODYNAMICAL EVOLUTION EFFECT ON THE SEA LEVEL CHANGING ALONG THE QUATERNARY PERIOD

The Caspian Sea as the largest lake in the world has different characteristics considering geosciences (Fig. I). In fact sea level changing is the most important happening in this region. Annually fluctuation impact on surrounding coastal area has serious damage and human society meet frequent destroyed phenomena. In this paper we are trying to reconstruct rapid Sea level changing in Holocene epoch by use paleontology evidences such as: Mollusks fossil and sedimentary fades record. In this research 254 Quaternary sediment core samples from exploring petroleum wells (M-l, G3-A) have been evaluated considering above mentioned and also more than 130 sea bottom recent sediments on view of biofacies and biostratigraphy studied. Our investigation results show that in the Caspian Sea basin at the Holocene epoch there are many periodic sea level fluctuations and climatologie impact is most important agent for sea level changing in this basin. Data results are showing that in the studied area there were many periodic rapid sea levels changing during the Quaternary period. The Caspian Sea has several fluctuations along 10,000years ago and its latest begin about 25years ago. Finally we can conclude that Caspian Sea level fluctuation could continue at future similar past time and climatologie impact and tectonic movement are important agents for sea level changing in this region

Multiple Pleistocene refugia and repeated phylogeographic breaks in the southern Caspian Sea region: Insights from the freshwater crab Potamon ibericum

AbstractAimPhylogeographic studies on a number of Western Palaearctic taxa imply that the southern Caspian Sea region served as a refugium during the Last Glacial Maximum (LGM). Nevertheless, the LGM biogeography of the terrestrial and freshwater organisms in this region is poorly understood. By studying phylogeography of a species of freshwater crab, we unravel the location of probable local refugia and colonization patterns across this topographically complex landscape.LocationSouthern Caspian Sea region.TaxonThe freshwater crab Potamon ibericum.MethodsWe inferred the demographic history of Potamon ibericum using 163 mtDNA Cox1 sequences from 16 localities. For a subset of specimens, we amplified mtDNA 16S and four nuclear markers (28S, Histone3, Enolase, NaK) to confirm the phylogeographic structure. We tested Pleistocene expansion–contraction dynamics, using species distribution modelling (SDM) and assessed morphological variability by geometric–morphometric methods.ResultsMitochondrial markers revealed the existence of three parapatrically distributed lineages in the western, central and eastern parts of the region. The more conserved nuclear markers did not reflect this. The SDM revealed the fundamental niche expansion of P. ibericum along the southern Caspian Sea during the LGM, agreeing with results from the Cox1 data of demographic expansions. Despite strong morphological resemblance, geometric–morphometrics elucidated clinal carapace shape variation.Main ConclusionsConsidering the Caspian Sea level fluctuations during the late Pleistocene, we hypothesize a scenario of demographic contraction during interglacial/warmer conditions, due to the Caspian Sea transgression and latitudinal range shift within the narrow distribution of the species between the southern Caspian Sea and northern slopes of the Alborz Mountains. During the glacial periods, the sea regressed and moist and warm conditions, characterizing glacial refugia, became prevalent in the region and caused isolated populations to expand. Our study confirms the deep transverse phylogeographic break, previously identified for Darevskia lizards in the region, and adds support to the presence of several LGM refugia in the southern Caspian Sea region.

THE CASPIAN SEA LEVEL FLUCTUATIONS INFLUENCE ON THE COASTAL LANDSCAPES OF MANGISTAU AND ATYRAU REGIONS OF KAZAKHSTAN

The article states main stages and impact of Caspian Sea level fluctuations on the north-eastern coastal landscapes (coastal area in Mangistau and Atyrau regions of Kazakhstan) for the periods of 1978 to 2014. Land cover changes and distribution of negative geo-ecological processes (salinity, flooding) were identifi ed based on the use of Landsat 1977, 1987, 1998, 2013 multispectral satellite images. Normalized Difference Water Index (NDWI) was calculated to identify the water table. On the basis of the values of brightness characteristics and synthesis of Landsat satellite images channels the article explains the correlation between vegetation and coast moisture conditions during transgressive phases and emergence of saline areas in the receding coastline. The author’s research objective was to evaluate the degree of sea level fluctuations impact (high, moderate, low) on different types of observed landscapes which have been exposed to marine transgressions in different geological epochs. As a result, the main conclusion was made that the intensity of the impact of sea level fluctuations on coastal landscapes to a large extent depends on the terrain, formed during long transgressive phases (1977–1995 years, the earliest- and late Caspian transgressions) which also connected with groundwater depth level, wind-driven waves zone of impact and the main characteristics of land cover. The author emphasizes that the study of modern areas affected by flooding will help to determine “risk flood zone” and to defi ne danger levels of areas for a different economic activities development.

Between the mountains and the sea: Late Holocene Caspian Sea level fluctuations and vegetation history of the lowland forests of northern Iran

Pollen analysis and radiocarbon dating of a core from northern Iran enable reconstructing the past three millennia of vegetation dynamics of the Caspian lowlands and Alborz foothills of central northern Iran as a function of Caspian Sea level oscillations, climate change and human impact. The high values of Alnus pollen and a diverse assemblage of non-pollen palynomorphs indicate that during most of the time span covered by the record a wet eutrophic to mesotrophic alder (Alnus cf. glutinosa) carr was present at the coring site. Only at the onset of the 2600-BP highstand event tree growth was hampered because of inundation. Our findings (including calcareous gyttja with remains of Charophytes; remnants of molluscs, freshwater snails, Foraminifera, Ostracoda, Algae and sponges) indicate that the highstand extended to and culminated in the period 2100 to 1900 calBP. Wingnut (Pterocarya fraxinifolia), which was a major component in the vegetation composition of the Caspian lowland from the beginning of the record, strongly decreased after ca. 1200 calBP, most probably due to a drier or colder climate. Artemisia and Chenopodiaceae and Amaranthaceae (C-A) show fluctuating and largely parallel values throughout the record, suggesting the natural co-occurrence and similar ecology of their corresponding plants in the coastal areas under the influence of Caspian Sea transgressions. The steep slopes south of the mire were probably most of the time covered by a species-rich deciduous forest predominated by hornbeam (Carpinus betulus) and beech (Fagus orientalis) accompanied by oak (Quercus castaneifolia), elms (Ulmus glabra/U. carpinifolia), Persian ironwood (Parrotia persica), maples (Acer velutinum/A. cappadocicum), box tree (Buxus hyrcana), grape (Vitis vinifera), ash (Fraxinus excelsior), and lime (Tilia platyphyllos). However, climate change and human impact triggered significant vegetational changes both in the lowland and the hilly upland. The first signal of human activity in the area can be inferred from findings of pollen of Juglans regia at ca. 2350 calBP and slightly later of Fagopyrum esculentum. A dramatic decline of tree pollen over the last centuries suggests that tree cover of both the lowland and upland landscape surrounding the mire declined and forests were increasingly replaced by open vegetation most likely as a result of intensified human activities.

Use of Exponential Regression for Modeling of Caspian Sea Level Fluctuation

Data on Caspian Sea level fluctuation, added up to April 2010 is examined in the article. Statistic analyses of these observations and in particular empiric histogram permits to consider that in sea level fluctuation the third stable condition appears at the level of –27 m. In previous works in sea level fluctuations up to 1995 two stable and one unstable condition were fi xed. Supplemented data shows that early developed models, based on polynomial regression are modeling level fluctuations with the transition of two defined conditions. A new improved model, based on exponential regression is proposed in the article, the solution of which demonstrates the transition of the sea level between three stable conditions.

A point-wise least squares spectral analysis (LSSA) of the Caspian Sea level fluctuations, using TOPEX/Poseidon and Jason-1 observations

The Caspian Sea has displayed considerable fluctuations in its water level during the past century. Knowledge of such fluctuation is vital for understanding the local hydrological cycles, climate of the region, and construction activities within the sea and along its shorelines. This study established a point-wise satellite altimetry approach to monitor the fluctuations of the Caspian Sea using a complete dataset of TOPEX/Poseidon for the period 1993 to the middle of 2002, and its follow-on Jason-1 for the period 2002 to August 2009. Therefore, 280 virtual time-series were constructed to monitor the fluctuations. The least squares spectral analysis (LSSA) method is, then employed to find the most significant frequencies of the time-series, while the statistical method of principle component analysis (PCA) is applied to extract the dominant variability of level variations. The study also used the observations of TOPEX/Poseidon and Jason-1 over the Volga River along with 5 years of Volga’s water discharge to study its influence on the Caspian Sea level changes. The LSSA results indicate that the lunar semidiurnal (M2) and the Sun semidiurnal (S2) frequencies are the main tidal frequencies of the Caspian Sea with the mean amplitude of 4.2 and 2.8cm, respectively. A statistically significant long-term frequency (12.5-years period) is also found from altimetry and tide gauge observations. A phase lag, related to the inter-annual frequencies of the Volga River was detected from the point-wise time-series showing level propagation from the northwest to the southeast of the sea. The cross-correlation between the power spectrum of Volga and that of the northern-most, middle, and southern-most points within the Caspian Sea were respectively 0.63, 0.51 and 0.4 of zero-lag correlation, corroborating the influence of the Volga River. The result of PCA also shows that different parts of the Caspian Sea exhibit different amplitudes of level variations, indicating that the point-wise approach, when employing all available satellite measurements could be a suitable method for a preliminary monitoring of this inland water resource as it gives accurate local fluctuations.

Geochemical Changes in the Caspian Salt Marshes Due to the Sea Level Fluctuations

The Caspian Sea is subject to alternating transgressions and regressions that exert a strong impact on the topography, sediments, vegetation, and soils in coastal zones. The last transgression of the Caspian Sea (1978-1995) caused the development of a marsh-lagoon system along the accumulative seashore of the Central Dagestan. Salt marshes are complex and dynamic systems highly vulnerable to sea level fluctuations; therefore, they may be considered as a regional model of rapid environmental changes. Hazards in coastal zones may critically change the soil geochemistry affecting agricultural potential of large areas. Assessments of risks of the natural hazards in coastal zones are extremely difficult unless the end-to-end understanding of all natural factors. The research in the Caspian region shows the impact of extreme events in the coastal zones. Detailed landscape-geochemical investigations of the Caspian salt marshes were carried out in 1995-1996 (during the final stage of the transgression period) and in 2001-2003 (during the period of the sea level stabilization). These coastal areas are influenced by different landscape-geochemical processes, such as sulfidization, gleyzation, ferrugination, humus accumulation, halogenesis, and changes of alkali-acidic conditions. The development of the processes characterizes different stages of the Caspian Sea level fluctuations. This paper presents a discussion on stages and rates of landscape-geochemical processes, formation of geochemical barriers, and trace elements distribution in soils of the salt marshes.

Climate changes and the Caspian Sea Level fluctuations in the Holocene and historical time

The influence of climate changes in Eurasia on the Caspian Sea level fluctuations in the Holocene is studied on the basis of historical data. The correspondence of the Late Khvalyn transgression to the time of the thawing of the European (Scandinavian) ice cap is revealed as well as that of the climatic optimum of the Holocene to the Boreal period (10-8 thousand years ago). In the next New-Caspian epoch, the Caspian Sea regression occurred. In the historical time, the maxima of cold snaps and Caspian Sea level are registered every five centuries.

A possible connection of Caspian Sea level fluctuations with meteorological factors and seismicity

The Caspian Sea has exhibited significant, wide-range fluctuations that have been traditionally attributed to variations in climatic agents. The objective of this research is to estimate the hydrologic budget and sea surface heights of the Caspian Sea from 1998 to 2005 to assess the contribution of meteorological and geological process to the Caspian Sea level variations. The water budget of the Caspian Sea from 1998 to 2005 was calculated using the state-of-the-art remote sensing techniques and ground-truth data. The Sea Surface heights of the Caspian Sea were constructed from the refined Topex/Poseidon altimetry data. The National Centers for Environmental Prediction/Department of Energy Reanalysis 2 meteorological data provided all the variables necessary for the Penman method to estimate evaporation over the Caspian Sea. The data of the Tropical Rainfall Measuring Mission were utilized to estimate precipitation onto the Caspian Sea. A strong agreement between the water budget residuals and Caspian Sea level variations signifies that Caspian Sea level oscillations for this time window are essentially controlled by climate-related factors. On the other hand, the relatively larger gaps between the water balance residuals and Caspian Sea level heights during 2000 and 2001 may indicate an impact of seismicity on Caspian Sea level oscillations as a result of two major earthquakes on November 25, 2000.