Luminita Preoteasa - Academia.edu (original) (raw)
Papers by Luminita Preoteasa
Journal of Coastal Research, 2013
La frequence des cycles de gel-degel dans les Carpates Roumains: The paper deals with the estimat... more La frequence des cycles de gel-degel dans les Carpates Roumains: The paper deals with the estimation of the freeze-thaw cycles occurrence potential in Romanian Carpathians, based upon the analysis of temperature data series collected from 27 mountain meteorological stations. The freeze-thaw weathering processes intensify within mountain ridges and slopes together with the increase of the altitude, depending on the number of freeze-thaw cycles (f.-t.c.), e.g.: Sinaia-92.2 f.-t.c. (1510 m), Babele -96 f.-t.c. (2206 m), vf. Omu -104.7 f-t.c. (2504 m). Besides this general rule, in the frame of each massive, one can distinguish a sudden increase of cycles occurrence frequencies in the depressions and valley domain due to the thermic invertions, e.g.: Braşov -101 f.-t.c. (504 m), Câmpulung Moldovenesc -113.2 f.-t..c. (659 m), Poiana Stampei -124.2 f-t.c. (920 m).
Journal of Coastal Research, 2013
Tătui, F., Vespremeanu-Stroe, A. and Preoteasa, L., 2013. The correlated behavior of sandbars and... more Tătui, F., Vespremeanu-Stroe, A. and Preoteasa, L., 2013. The correlated behavior of sandbars and foredunes on a nontidal coast (Danube Delta, Romania) In:
Journal of Coastal Research, 2013
Journal of Environmental Radioactivity, 2016
This is the first study reporting recent sedimentation rates data (e.g. the past 120-150 years) f... more This is the first study reporting recent sedimentation rates data (e.g. the past 120-150 years) for the Cruhlig Lake situated in the Danube Delta. The aim of this study is to analyse the recent sedimentation rates using the (210)Pb dating method and identifying the heavy metal pollutants and their variability in time. Five sediment cores were taken with a gravity corer and - after drying the sliced samples-physical parameters, organic material and inorganic carbon content were determined. The total (210)Pb content was measured via (210)Po by alpha spectrometry, while supported (210)Pb was measured by (226)Ra (trough short life (222)Rn daughters) with HPGe detectors. Heavy metals were determined by ICP-MS; from the 64 measured elements, only exceeding values of Al, As, Cd, Co, Cs, Cr, Cu, Fe, Hg, K, Li, Mg, Mn, Ni, Pb and Zn are discussed. After applying the CRS model, ages and sedimentation rates were calculated. The average sedimentation rate of the Cruhlig Lake is 0.21 ± 0.02 g/cm(2)y, Minimum values (0.05 ± 0.003 g/cm(2)y) are registered along the eastern shoreline of the lake before 1913, while maximum values are recorded due to the flooding in 2006 in the western side (1.34 ± 0.12 g/cm(2)y). Recent sedimentation rates divide the lake into three areas: the secluded eastern near shore part (0.63 ± 0.07 g/cm(2)y), the centre of the lake (0.92 ± 0.05 g/cm(2)y) and the dynamic western area, where most sediment transport takes place (1.13 ± 0.01 g/cm(2)y). The sedimentation pattern proves this lake to be very sensitive to fluvial discharge fluctuations. The building of the Iron Gate dams (1972 and 1985) had a negative impact on the sedimentation decreasing it with 58.74%, while after 1989 these values grew 2.25 times. The lake received a quantity of sediment rich in heavy metals in 1992 ± 3 y, which settled mostly on the eastern part. Values for Cd, Co, Cr, Hg, Pb and Zn are up to five times higher in 1980 ± 5 y in the eastern part of the lake, while Cd, Co, Cr and Ni are twice as high as the values measured for the marine substrate. Values of As show increasing of up to 150% in 2006 ± 2 y throughout the whole surface of the lake.
Tătui, F., Vespremeanu-Stroe, A. and Preoteasa, L., 2013. The correlated behavior of sandbars and... more Tătui, F., Vespremeanu-Stroe, A. and Preoteasa, L., 2013. The correlated behavior of sandbars and foredunes on a nontidal coast (Danube Delta, Romania) In:
Geomorphology, 2015
The asymmetric Sf. Gheorghe lobe is the only active lobe in the Danube delta associated with a ri... more The asymmetric Sf. Gheorghe lobe is the only active lobe in the Danube delta associated with a river-mouth bar (and related barrier islands and spits) that has continuously displayed cyclic development during the last 1500 years. During the early cycles, the Sf. Gheorghe distributary experienced a significant increase in sediment load (by an order of magnitude) as a result of the successive avulsions occurred 1.5–1.2 ka, which redistributed more water and sediment captured from the neighboring branches of Împuţita (southern distributary of the Sulina arm) and Dunavăţ. Morphological and sedimentological analyses together with a newly obtained chronology throw light on the multiple ridgeset (10) structure of Sf. Gheorghe lobe, each of them (excepting the first one) following a common evolutionary pattern reflected by the cyclic succession of the recurring stages: i) subaqueous mouth bar building, ii) barrier island emergence, and iii) transformation into a barrier spit with several secondary spits. The spits become encased into the muddy deltaic plain as narrow sandy ridges building out on the downdrift side of the lobe as a barrier-marsh plain, whereas the updrift side constantly accreted fed by longshore currents, forming a classic beach ridge plain. The size of each ridgeset increased exponentially with every new cycle due to the constant lengthening of the coastline as the downdrift side of the lobe advanced seaward through a series of progressively larger similar quadrilaterals, yielding a corresponding geometric progression of the delta front size. Even though each newly formed ridgeset (cycle) had a longer lifespan (the latest cycles lasting 4–5 times longer than the first ones: 200–440 years versus 50–80 years), the evolutionary model remained unchanged as long as the balance between wave- and river-borne sediments, defined by the sedimentary index (Si), remained constantly low(Si ≤ 0.1),whereas the mean advance rates of the river mouth remained constant at c.10 m/year. Abrupt changes occurred within the last cycle (since the beginning of the 20th century) as a consequence of human-induced depletion of sediment supplied by the Danube flow, and is mainly expressed by the complete cessation of the updrift coastal progradation and the prevalence of erosion in front of the river mouth. These changes, which engendered a threefold increase of the Si (0.37 at present), are reflected by the recent (1930s–present) river mouth dynamics, characterized by cessation of its long-term seaward expansion in favor of downdrift migration. This is indicative of the transition of the Sf. Gheorghe mouth from an asymmetric to a deflected wave-influenced delta morphology whose current developments mark a significant change in the multicentennial cyclic evolutionary pattern. The asymmetric to deflected transition reflects the net increase in the influence of wave-driven sediment circulation on river mouth morphology, corresponding to a critical Si threshold of ca. 0.2 (≤0.2: asymmetric; N0.2: deflected).
The analysis of the eolian sand transport in the Danube Delta This paper presents the charcateris... more The analysis of the eolian sand transport in the Danube Delta This paper presents the charcateristics of aeolian sand transport regime in the Danube Delta, obtained following the technique proposed by Fryberger, 1979. This method estimate: Drift Potential (DP) or the quantity of sand displaced by the winds exceeding the threshold of particle entrainment into the airflow, the Resultant Drift Direction (RDD) or the mean direction on which the sand is moving, Resultant Drift Potential (RDP) or the quantity of sand that moves along the RDD, RDP/DP or the directional variability of the wind. The results of this study for four stations in the Danube Delta are presented, showing the spatial ant temporal distribution of this indices. Thus the wind climate is found to be included in the high wind-energy category (72.5 vu -Sf. Gheorghe, 63 vu -Caraorman). The directional wind variability is medium allowing the sand movement in a dominant direction: Sulina -197,1 0 ; Sf.Gheorghe -182,4 0 , Caraorman -178,1 0 (the directions are measured clockwise from north direction). The orientation of parabolic dunes from Letea and Caraorman dune ridge plains shows a good correspondence between the potential mean direction transport and the real ones. The monthly distribution of sand transport rate displays the presence of two morphodynamic seasons: the active cold season, october-aprilie, with a potential monthly transport estimated at 22,8 mc/m and a lowintermediate one, mai-september, with 6,6 mc/m/month. Cuvinte cheie: Delta Dunării ,Drift Potenţial, Rata transportului de nisip, Roza nisipului,
Textural parameters are regarded as precious informational source for the genesis and evolution o... more Textural parameters are regarded as precious informational source for the genesis and evolution of coastal sedimentary environments. The purpose of this paper is to give a detailed insight of the grain size, sorting and skewness of sediments from the beach-dune system as well as to establish the relationships between them, the local characteristics of shaping agents and the coastal morphological units. Based on 139 sand samples prelevated from the beach-dune system of the Sărăturile beach ridge plain and of the Sacalin barrier Island, multivariate statistical analyses were used to emphasize the relations between the textural parameters with the morphology and the distance up to sediment sources. The main findings are (i) a slight increase of the grain size from south to north or better expressed from Danube mouth to the updrift side of Sărăturile beach ridge plain, (ii) a net difference in sorting pattern along transverse profiles from the northern Sacalin showing that beaches and f...
Journal of Coastal Research, 2014
Tătui, F., Vespremeanu-Stroe, A, Preoteasa, L., 2014. Alongshore variations in beach-dune system ... more Tătui, F., Vespremeanu-Stroe, A, Preoteasa, L., 2014. Alongshore variations in beach-dune system response to major storm events on the Danube Delta coast.
In the Romanian Carpathians, developed on crystalline and volcanic rocks, the main geomorphologic... more In the Romanian Carpathians, developed on crystalline and volcanic rocks, the main geomorphological processes are rockfalls, debris fl ows, and topples. In the eastern part of the Eastern Carpathians, built up of Cretaceous and Paleogene fl ysch, landslides and mudfl ows are of major signifi cance. High and middle mountain karst features and cave systems are also widespread. In the alpine area of the Southern and Eastern Carpathians, avalanches are common on the steep slopes of
Coastal Research Library, 2015
ABSTRACT This chapter is about the sand spits formation, evolution and morphology at the Danube m... more ABSTRACT This chapter is about the sand spits formation, evolution and morphology at the Danube mouths, developed within the general framework of the virtually tideless Black Sea basin in a medium-wave energy environment. It deals with both barrier spits and islands, in respect to their processual development as most of the Danube delta spits derive from former barrier islands. The morphodynamics of the modern spit barriers associated to Danube mouths is discussed in relation with human induced fluvial discharge decline and long-term storminess variability. Regarding the Danube delta evolution, based on the morphology, internal structure and revised chronologies, the authors argue for the first time that all open-coast deltaic lobes had or have an evolution marked by the cyclic development of sandy barrier spits and islands in front of their downdrift units.
… de geomorfologievol, 2008
Cuvinte-cheie: lacuri glaciare, batimetrie, micromorfologie glaciară, subsăpare glaciară, Carpaţi... more Cuvinte-cheie: lacuri glaciare, batimetrie, micromorfologie glaciară, subsăpare glaciară, Carpaţii Meridionali ew insights regardingthe glacial lakes morphology from Southern Carpathians. The present study aims to provide new and precise data regarding the glacial lakes morphology from Southern Carpathians. Based on detailed bathymetric surveys, this paper analyses morfometric and morphological characteristics of glacial lakes and compares them with previous results. The comparative analysis of the morphometric parameters analysis featuring the lake basin reveals significant differences between the present study results (shoreline configuration, surface, lake basin volume, average and maximum depth) and those elswhere reported in the literature. Average and maximum depths and water volume measured values are significantly greater than previously reported; for maximum depths we measured the following values: Bâlea -16.9 m versus -11.3 m; Capra -13.1 m versus -8 m; Podragu -18.7 m versus -15.5 m; Bucura -17.5 m versus -15.7 m; Slăveiu -9.5 m versus -6.1 m; Tăul Porţii -4.7 m versus -2.3m. The small-scale landforms placed on the lake basin (troughts, platforms, bowl like excavations) represent the results of the glacial processes (glacial overdeepening, subglacial torrents erosion). Glacial lakes were classified according to: (i) the bathygraphic curves shape within three morphotypes: convex shape (Lia, Slăveiu), linear or linear-convex (Buda, Galeşu, Capra) and convex-concave or mixted shape (Bâlea, Podragu, Ana) and (ii) the slope distribution on depth levels: (1) low and medium gradient slope (Ana); (2) steep slopes and cvasi-horizontal bottom (Galeşu) and cvasi-horizontal bottoms and bowl like excavations (Bâlea and Podragu). Further works should be carried on the glacial lake morphology on the Romanian Carpathians, by bathymetric database enlargement in order to conceive a new glacial lakes basin typology based on morphometric and morphogenetic criteria.
The largest dunefields in the Danube delta developed during the Late-Holocene on the Caraorman an... more The largest dunefields in the Danube delta developed during the Late-Holocene on the Caraorman and Letea beach ridge plains. Our research focused upon the reconstruction of aeolian landforms in the Danube Delta. Field based investigations of the modern aeolian morphology revealed the succession of different aeolian activity phases shaping the modern aeolian landforms. One phase of aeolian modification of the landforms occurred during conditions of generally low rugosity (bare and grassy areas) while another one followed when the development of aeolian landforms was constrained by the emplacement of woody vegetation. Optically stimulated luminescence (OSL) ages were used in order to develop a chronology of aeolian activity in the Danube Delta during the Late-Holocene. The OSL ages indicate that the interplay between sea-level, sediment availability and climate variability over the last 2400 years resulted in a dunefield pattern containing several dune generations. Moreover, our OSL ages together with the ages produced by lead to a new hypothesis for the development of the Letea complex ridge plain, according to which at least three phases with different rates of progradation occurred: (1) rapid rates at the beginning, between 3640 ± 140 yrs to 2300 ± 420 yrs ago, (2) slow rates from 2300 ± 420 yrs to 900-1200 yrs ago and (3) rapid rates since 900-1200 yrs ago until the initiation of the Chilia secondary delta.
… de geomorfologievol, 2009
The largest dunefields in the Danube delta developed during the Late-Holocene on the Caraorman an... more The largest dunefields in the Danube delta developed during the Late-Holocene on the Caraorman and Letea prograded barriers. The sand dunes in the Danube delta are one of the most pristine coastal dunes in Europe. Our research focused upon the reconstruction of aeolian landforms in the Danube delta. Field based investigations of the modern aeolian morphology revealed the succession of different aeolian activity phases shaping the modern aeolian landforms. One phase of aeolian modification of the landforms occurred during conditions of generally low rugosity (bare and grassy areas) while another one followed when the development of aeolian landforms was constrained by the emplacement of woody vegetation. The highest altitudes of the prograded barrier at Letea correspond to the accretion fronts developed in association with the forest. Mapping of the morphologic features of the Letea complex ridge plain shows the discordant superposition of the aeolian landforms over the marine wave-laid sediments (beach ridges). The relationship between the resultant migration direction of the dunes (RMDD) and the underlying beach ridge orientation is an important controlling factor on the development of the aeolian morphology. Elongated parabolic dunes occur where the RMDD is concordant with the subjacent beach ridge alignment. A combination of dendrochronological dates and optically stimulated luminescence (OSL) ages were used in order to develop a chronology of aeolian activity in the Danube delta during the Late-Holocene. The preliminary OSL ages indicate that the interplay between sea-level, sediment availability and climate variability over the last 2400 yrs resulted in a dunefield pattern representing several dune generations. Our OSL ages, together with the ages produced by advocate for a new hypothesis regarding Letea complex ridge plain development according to which at least three phases with different rates of progradation occurred:
Geomorphology, 2007
Beach-dune seasonal elevation changes, aeolian sand transport measurements, bathymetric surveys a... more Beach-dune seasonal elevation changes, aeolian sand transport measurements, bathymetric surveys and shoreline evolution assessments were used to investigate annual and seasonal patterns of dune development on Sfântu Gheorghe beach, the Danube delta coast, from 1997 to 2004. Dune volume increased consistently (1.96 m 3 m − 1 y − 1 to 5.1 m 3 m − 1 y − 1 ) over this 7-year period with higher rates in the southward (downdrift) direction. Dune aggradation is periodically limited by storms, each of which marks a new evolutionary phase of the beach-dune system. As a consequence of the variable beach morphology and vegetation density during a year, foredune growth occurs during the April-December interval while between December and April a slightly erosive tendency is present. The pattern of erosion and deposition shown by the topographical surveys is in good agreement with the sand transport measurements and demonstrates the presence of a vigorous sand flux over the foredunes which is 20-50% smaller than on the beach. This high sand flux, due to low precipitation and sparse vegetation cover, creates an aerodynamically efficient morphology on the seaward dune slope. The seaward dune face accretes during low to medium onshore winds (5.5-12 m s − 1 ) and erodes during high winds (N 12 m s − 1 ).
Journal of Coastal Research, 2013
La frequence des cycles de gel-degel dans les Carpates Roumains: The paper deals with the estimat... more La frequence des cycles de gel-degel dans les Carpates Roumains: The paper deals with the estimation of the freeze-thaw cycles occurrence potential in Romanian Carpathians, based upon the analysis of temperature data series collected from 27 mountain meteorological stations. The freeze-thaw weathering processes intensify within mountain ridges and slopes together with the increase of the altitude, depending on the number of freeze-thaw cycles (f.-t.c.), e.g.: Sinaia-92.2 f.-t.c. (1510 m), Babele -96 f.-t.c. (2206 m), vf. Omu -104.7 f-t.c. (2504 m). Besides this general rule, in the frame of each massive, one can distinguish a sudden increase of cycles occurrence frequencies in the depressions and valley domain due to the thermic invertions, e.g.: Braşov -101 f.-t.c. (504 m), Câmpulung Moldovenesc -113.2 f.-t..c. (659 m), Poiana Stampei -124.2 f-t.c. (920 m).
Journal of Coastal Research, 2013
Tătui, F., Vespremeanu-Stroe, A. and Preoteasa, L., 2013. The correlated behavior of sandbars and... more Tătui, F., Vespremeanu-Stroe, A. and Preoteasa, L., 2013. The correlated behavior of sandbars and foredunes on a nontidal coast (Danube Delta, Romania) In:
Journal of Coastal Research, 2013
Journal of Environmental Radioactivity, 2016
This is the first study reporting recent sedimentation rates data (e.g. the past 120-150 years) f... more This is the first study reporting recent sedimentation rates data (e.g. the past 120-150 years) for the Cruhlig Lake situated in the Danube Delta. The aim of this study is to analyse the recent sedimentation rates using the (210)Pb dating method and identifying the heavy metal pollutants and their variability in time. Five sediment cores were taken with a gravity corer and - after drying the sliced samples-physical parameters, organic material and inorganic carbon content were determined. The total (210)Pb content was measured via (210)Po by alpha spectrometry, while supported (210)Pb was measured by (226)Ra (trough short life (222)Rn daughters) with HPGe detectors. Heavy metals were determined by ICP-MS; from the 64 measured elements, only exceeding values of Al, As, Cd, Co, Cs, Cr, Cu, Fe, Hg, K, Li, Mg, Mn, Ni, Pb and Zn are discussed. After applying the CRS model, ages and sedimentation rates were calculated. The average sedimentation rate of the Cruhlig Lake is 0.21 ± 0.02 g/cm(2)y, Minimum values (0.05 ± 0.003 g/cm(2)y) are registered along the eastern shoreline of the lake before 1913, while maximum values are recorded due to the flooding in 2006 in the western side (1.34 ± 0.12 g/cm(2)y). Recent sedimentation rates divide the lake into three areas: the secluded eastern near shore part (0.63 ± 0.07 g/cm(2)y), the centre of the lake (0.92 ± 0.05 g/cm(2)y) and the dynamic western area, where most sediment transport takes place (1.13 ± 0.01 g/cm(2)y). The sedimentation pattern proves this lake to be very sensitive to fluvial discharge fluctuations. The building of the Iron Gate dams (1972 and 1985) had a negative impact on the sedimentation decreasing it with 58.74%, while after 1989 these values grew 2.25 times. The lake received a quantity of sediment rich in heavy metals in 1992 ± 3 y, which settled mostly on the eastern part. Values for Cd, Co, Cr, Hg, Pb and Zn are up to five times higher in 1980 ± 5 y in the eastern part of the lake, while Cd, Co, Cr and Ni are twice as high as the values measured for the marine substrate. Values of As show increasing of up to 150% in 2006 ± 2 y throughout the whole surface of the lake.
Tătui, F., Vespremeanu-Stroe, A. and Preoteasa, L., 2013. The correlated behavior of sandbars and... more Tătui, F., Vespremeanu-Stroe, A. and Preoteasa, L., 2013. The correlated behavior of sandbars and foredunes on a nontidal coast (Danube Delta, Romania) In:
Geomorphology, 2015
The asymmetric Sf. Gheorghe lobe is the only active lobe in the Danube delta associated with a ri... more The asymmetric Sf. Gheorghe lobe is the only active lobe in the Danube delta associated with a river-mouth bar (and related barrier islands and spits) that has continuously displayed cyclic development during the last 1500 years. During the early cycles, the Sf. Gheorghe distributary experienced a significant increase in sediment load (by an order of magnitude) as a result of the successive avulsions occurred 1.5–1.2 ka, which redistributed more water and sediment captured from the neighboring branches of Împuţita (southern distributary of the Sulina arm) and Dunavăţ. Morphological and sedimentological analyses together with a newly obtained chronology throw light on the multiple ridgeset (10) structure of Sf. Gheorghe lobe, each of them (excepting the first one) following a common evolutionary pattern reflected by the cyclic succession of the recurring stages: i) subaqueous mouth bar building, ii) barrier island emergence, and iii) transformation into a barrier spit with several secondary spits. The spits become encased into the muddy deltaic plain as narrow sandy ridges building out on the downdrift side of the lobe as a barrier-marsh plain, whereas the updrift side constantly accreted fed by longshore currents, forming a classic beach ridge plain. The size of each ridgeset increased exponentially with every new cycle due to the constant lengthening of the coastline as the downdrift side of the lobe advanced seaward through a series of progressively larger similar quadrilaterals, yielding a corresponding geometric progression of the delta front size. Even though each newly formed ridgeset (cycle) had a longer lifespan (the latest cycles lasting 4–5 times longer than the first ones: 200–440 years versus 50–80 years), the evolutionary model remained unchanged as long as the balance between wave- and river-borne sediments, defined by the sedimentary index (Si), remained constantly low(Si ≤ 0.1),whereas the mean advance rates of the river mouth remained constant at c.10 m/year. Abrupt changes occurred within the last cycle (since the beginning of the 20th century) as a consequence of human-induced depletion of sediment supplied by the Danube flow, and is mainly expressed by the complete cessation of the updrift coastal progradation and the prevalence of erosion in front of the river mouth. These changes, which engendered a threefold increase of the Si (0.37 at present), are reflected by the recent (1930s–present) river mouth dynamics, characterized by cessation of its long-term seaward expansion in favor of downdrift migration. This is indicative of the transition of the Sf. Gheorghe mouth from an asymmetric to a deflected wave-influenced delta morphology whose current developments mark a significant change in the multicentennial cyclic evolutionary pattern. The asymmetric to deflected transition reflects the net increase in the influence of wave-driven sediment circulation on river mouth morphology, corresponding to a critical Si threshold of ca. 0.2 (≤0.2: asymmetric; N0.2: deflected).
The analysis of the eolian sand transport in the Danube Delta This paper presents the charcateris... more The analysis of the eolian sand transport in the Danube Delta This paper presents the charcateristics of aeolian sand transport regime in the Danube Delta, obtained following the technique proposed by Fryberger, 1979. This method estimate: Drift Potential (DP) or the quantity of sand displaced by the winds exceeding the threshold of particle entrainment into the airflow, the Resultant Drift Direction (RDD) or the mean direction on which the sand is moving, Resultant Drift Potential (RDP) or the quantity of sand that moves along the RDD, RDP/DP or the directional variability of the wind. The results of this study for four stations in the Danube Delta are presented, showing the spatial ant temporal distribution of this indices. Thus the wind climate is found to be included in the high wind-energy category (72.5 vu -Sf. Gheorghe, 63 vu -Caraorman). The directional wind variability is medium allowing the sand movement in a dominant direction: Sulina -197,1 0 ; Sf.Gheorghe -182,4 0 , Caraorman -178,1 0 (the directions are measured clockwise from north direction). The orientation of parabolic dunes from Letea and Caraorman dune ridge plains shows a good correspondence between the potential mean direction transport and the real ones. The monthly distribution of sand transport rate displays the presence of two morphodynamic seasons: the active cold season, october-aprilie, with a potential monthly transport estimated at 22,8 mc/m and a lowintermediate one, mai-september, with 6,6 mc/m/month. Cuvinte cheie: Delta Dunării ,Drift Potenţial, Rata transportului de nisip, Roza nisipului,
Textural parameters are regarded as precious informational source for the genesis and evolution o... more Textural parameters are regarded as precious informational source for the genesis and evolution of coastal sedimentary environments. The purpose of this paper is to give a detailed insight of the grain size, sorting and skewness of sediments from the beach-dune system as well as to establish the relationships between them, the local characteristics of shaping agents and the coastal morphological units. Based on 139 sand samples prelevated from the beach-dune system of the Sărăturile beach ridge plain and of the Sacalin barrier Island, multivariate statistical analyses were used to emphasize the relations between the textural parameters with the morphology and the distance up to sediment sources. The main findings are (i) a slight increase of the grain size from south to north or better expressed from Danube mouth to the updrift side of Sărăturile beach ridge plain, (ii) a net difference in sorting pattern along transverse profiles from the northern Sacalin showing that beaches and f...
Journal of Coastal Research, 2014
Tătui, F., Vespremeanu-Stroe, A, Preoteasa, L., 2014. Alongshore variations in beach-dune system ... more Tătui, F., Vespremeanu-Stroe, A, Preoteasa, L., 2014. Alongshore variations in beach-dune system response to major storm events on the Danube Delta coast.
In the Romanian Carpathians, developed on crystalline and volcanic rocks, the main geomorphologic... more In the Romanian Carpathians, developed on crystalline and volcanic rocks, the main geomorphological processes are rockfalls, debris fl ows, and topples. In the eastern part of the Eastern Carpathians, built up of Cretaceous and Paleogene fl ysch, landslides and mudfl ows are of major signifi cance. High and middle mountain karst features and cave systems are also widespread. In the alpine area of the Southern and Eastern Carpathians, avalanches are common on the steep slopes of
Coastal Research Library, 2015
ABSTRACT This chapter is about the sand spits formation, evolution and morphology at the Danube m... more ABSTRACT This chapter is about the sand spits formation, evolution and morphology at the Danube mouths, developed within the general framework of the virtually tideless Black Sea basin in a medium-wave energy environment. It deals with both barrier spits and islands, in respect to their processual development as most of the Danube delta spits derive from former barrier islands. The morphodynamics of the modern spit barriers associated to Danube mouths is discussed in relation with human induced fluvial discharge decline and long-term storminess variability. Regarding the Danube delta evolution, based on the morphology, internal structure and revised chronologies, the authors argue for the first time that all open-coast deltaic lobes had or have an evolution marked by the cyclic development of sandy barrier spits and islands in front of their downdrift units.
… de geomorfologievol, 2008
Cuvinte-cheie: lacuri glaciare, batimetrie, micromorfologie glaciară, subsăpare glaciară, Carpaţi... more Cuvinte-cheie: lacuri glaciare, batimetrie, micromorfologie glaciară, subsăpare glaciară, Carpaţii Meridionali ew insights regardingthe glacial lakes morphology from Southern Carpathians. The present study aims to provide new and precise data regarding the glacial lakes morphology from Southern Carpathians. Based on detailed bathymetric surveys, this paper analyses morfometric and morphological characteristics of glacial lakes and compares them with previous results. The comparative analysis of the morphometric parameters analysis featuring the lake basin reveals significant differences between the present study results (shoreline configuration, surface, lake basin volume, average and maximum depth) and those elswhere reported in the literature. Average and maximum depths and water volume measured values are significantly greater than previously reported; for maximum depths we measured the following values: Bâlea -16.9 m versus -11.3 m; Capra -13.1 m versus -8 m; Podragu -18.7 m versus -15.5 m; Bucura -17.5 m versus -15.7 m; Slăveiu -9.5 m versus -6.1 m; Tăul Porţii -4.7 m versus -2.3m. The small-scale landforms placed on the lake basin (troughts, platforms, bowl like excavations) represent the results of the glacial processes (glacial overdeepening, subglacial torrents erosion). Glacial lakes were classified according to: (i) the bathygraphic curves shape within three morphotypes: convex shape (Lia, Slăveiu), linear or linear-convex (Buda, Galeşu, Capra) and convex-concave or mixted shape (Bâlea, Podragu, Ana) and (ii) the slope distribution on depth levels: (1) low and medium gradient slope (Ana); (2) steep slopes and cvasi-horizontal bottom (Galeşu) and cvasi-horizontal bottoms and bowl like excavations (Bâlea and Podragu). Further works should be carried on the glacial lake morphology on the Romanian Carpathians, by bathymetric database enlargement in order to conceive a new glacial lakes basin typology based on morphometric and morphogenetic criteria.
The largest dunefields in the Danube delta developed during the Late-Holocene on the Caraorman an... more The largest dunefields in the Danube delta developed during the Late-Holocene on the Caraorman and Letea beach ridge plains. Our research focused upon the reconstruction of aeolian landforms in the Danube Delta. Field based investigations of the modern aeolian morphology revealed the succession of different aeolian activity phases shaping the modern aeolian landforms. One phase of aeolian modification of the landforms occurred during conditions of generally low rugosity (bare and grassy areas) while another one followed when the development of aeolian landforms was constrained by the emplacement of woody vegetation. Optically stimulated luminescence (OSL) ages were used in order to develop a chronology of aeolian activity in the Danube Delta during the Late-Holocene. The OSL ages indicate that the interplay between sea-level, sediment availability and climate variability over the last 2400 years resulted in a dunefield pattern containing several dune generations. Moreover, our OSL ages together with the ages produced by lead to a new hypothesis for the development of the Letea complex ridge plain, according to which at least three phases with different rates of progradation occurred: (1) rapid rates at the beginning, between 3640 ± 140 yrs to 2300 ± 420 yrs ago, (2) slow rates from 2300 ± 420 yrs to 900-1200 yrs ago and (3) rapid rates since 900-1200 yrs ago until the initiation of the Chilia secondary delta.
… de geomorfologievol, 2009
The largest dunefields in the Danube delta developed during the Late-Holocene on the Caraorman an... more The largest dunefields in the Danube delta developed during the Late-Holocene on the Caraorman and Letea prograded barriers. The sand dunes in the Danube delta are one of the most pristine coastal dunes in Europe. Our research focused upon the reconstruction of aeolian landforms in the Danube delta. Field based investigations of the modern aeolian morphology revealed the succession of different aeolian activity phases shaping the modern aeolian landforms. One phase of aeolian modification of the landforms occurred during conditions of generally low rugosity (bare and grassy areas) while another one followed when the development of aeolian landforms was constrained by the emplacement of woody vegetation. The highest altitudes of the prograded barrier at Letea correspond to the accretion fronts developed in association with the forest. Mapping of the morphologic features of the Letea complex ridge plain shows the discordant superposition of the aeolian landforms over the marine wave-laid sediments (beach ridges). The relationship between the resultant migration direction of the dunes (RMDD) and the underlying beach ridge orientation is an important controlling factor on the development of the aeolian morphology. Elongated parabolic dunes occur where the RMDD is concordant with the subjacent beach ridge alignment. A combination of dendrochronological dates and optically stimulated luminescence (OSL) ages were used in order to develop a chronology of aeolian activity in the Danube delta during the Late-Holocene. The preliminary OSL ages indicate that the interplay between sea-level, sediment availability and climate variability over the last 2400 yrs resulted in a dunefield pattern representing several dune generations. Our OSL ages, together with the ages produced by advocate for a new hypothesis regarding Letea complex ridge plain development according to which at least three phases with different rates of progradation occurred:
Geomorphology, 2007
Beach-dune seasonal elevation changes, aeolian sand transport measurements, bathymetric surveys a... more Beach-dune seasonal elevation changes, aeolian sand transport measurements, bathymetric surveys and shoreline evolution assessments were used to investigate annual and seasonal patterns of dune development on Sfântu Gheorghe beach, the Danube delta coast, from 1997 to 2004. Dune volume increased consistently (1.96 m 3 m − 1 y − 1 to 5.1 m 3 m − 1 y − 1 ) over this 7-year period with higher rates in the southward (downdrift) direction. Dune aggradation is periodically limited by storms, each of which marks a new evolutionary phase of the beach-dune system. As a consequence of the variable beach morphology and vegetation density during a year, foredune growth occurs during the April-December interval while between December and April a slightly erosive tendency is present. The pattern of erosion and deposition shown by the topographical surveys is in good agreement with the sand transport measurements and demonstrates the presence of a vigorous sand flux over the foredunes which is 20-50% smaller than on the beach. This high sand flux, due to low precipitation and sparse vegetation cover, creates an aerodynamically efficient morphology on the seaward dune slope. The seaward dune face accretes during low to medium onshore winds (5.5-12 m s − 1 ) and erodes during high winds (N 12 m s − 1 ).