The evolution of an asymmetric deltaic lobe (Sf. Gheorghe, Danube) in association with cyclic development of the river-mouth bar: Long-term pattern and present adaptations to human-induced sediment depletion

Preoteasa, Luminiţa; Vespremeanu‐Stroe, Alfred; Tătui, Florin; Zăinescu, Florin; Timar-Gabor, Alida; Cîrdan, Ionela

doi:10.1016/j.geomorph.2015.09.023

Cited by 40 publications

(17 citation statements)

References 25 publications

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“…(a) Pre-and post-dam sediment loads in Mt/year for the Arno River (Billi and Rinaldi, 1997), the Medjerda River (Sliti, 1990;Rand McNally Encyclopedia of World Rivers, 1980;Meybeck and Ragu, 1996;Tiveront, 1960;Milliman and Farnsworth, 2011), the Ebro River (Palanque et al, 1990;Vericat and Batalla, 2006), the Po River (Idroser, 1994 cited in Simeoni and Corbau, 2009;Syvitski and Kettner, 2007), the Ceyhan River (EIE, 1993, cited by Cetin et al, 1999), the Rhône River (Milliman and Meade, 1983;Ollivier et al, 2010;Dumas et al, 2015;OSR, 2016), the Moulouya River (Snoussi et al, 2002), the Ombrone River (Milliman and Farnsworth, 2011), the Nile River (Syvitski and Saito, 2007;Milliman and Farnsworth, 2011), and the Danube River (Milliman and Farnsworth, 2011;Preoteasa et al, 2016) (Church et al, 2004), Nile (Becker and Sultan 2009;Marriner et al, 2012;Stanley and Clemente, 2017), Po (Bondesan et al, 1995), Rhône (Vella and Provansal, 2000), Ebro (Ibáñez et al, 1997), Ombrone (Pranzini, 1994), Medjerda (World Bank, 2011;Louati et al, 2014). Note that sediment loads in the European rivers have also undergone reductions related to catchment reforestation during both the pre-dam and the recent to present post-dam periods, as shown by the budget calculations of Provansal et al (2014) for the Rhône.…”

Section: Discussionmentioning

confidence: 99%

“…Some of the characteristics of the ten selected deltas, which are also among the largest in the Mediterranean, are shown in Table 1: Selection of data on the ten deltas and on their catchments and river discharge. Danube (Coleman and Huh, 2004;Preoteasa et al, 2016), Ebro, Nile and Po (Coleman and Huh, 2004), Arno, Ceyhan (Syvitski and Saito, 2007), Rhône (Provansal et al, 2014), Ombrone (Syvitski et al, 2005), Medjerda (Meybeck and Ragu, 1996), Moulouya (Snoussi et al, 2002;Milliman and Farnsworth, 2011 …”

Section: Research Articlementioning

confidence: 99%

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River delta shoreline reworking and erosion in the Mediterranean and Black Seas: the potential roles of fluvial sediment starvation and other factors

Besset

Anthony

Sabatier

2017

Elementa: Science of the Anthropocene

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The Mediterranean basin (including the Black Sea) is characterized by a plethora of deltas that have developed in a wave-influenced setting. Many of these deltas are sourced in sediments by river catchments that have been variably dammed. The vulnerability status of a selection of ten deltas subject to different levels of reduction in fluvial sediment supply following damming was analysed by quantifying changes in delta protrusion area and protrusion angle over the last 30 years. The rationale for choosing these two metrics, which do not require tricky calculations of longshore bedload transport volumes and river ‘influence’, is that as sediment supply wanes, increasing relative efficiency of waves leads to longshore redistribution of reworked sediments and progressive ‘flattening’ of the delta protrusion. The results show that eight of the ten deltas (Nile, Rhône, Ebro, Ceyhan, Arno, Ombrone, Moulouya, Medjerda) are in erosion, whereas two (Danube, Po) show stability, but the statistical relationship between change in delta protrusion area and sediment flux reduction is poor, thus suggesting that the role of dams in causing delta shoreline erosion may have been over-estimated. But this poor relationship could also be due to a long temporal lag between dam construction and bedload removal and transport to the coast downstream of dams, and, where the delta protrusion is being eroded, to bedload trapping by shoreline engineering structures and by elongating delta-flank spits. Other potential influential factors in shoreline change include subsidence, sea-level rise, storminess, exceptional river floods, and managed sediment releases downstream of dams. A longer observation period and high-resolution sediment-budget studies will be necessary to determine more definitively to which extent continued trapping of sediment behind dams will impact overall delta stability in the Mediterranean and Black Seas. Mitigation of delta erosion is likely to become costlier under continued sediment starvation and sea-level rise.

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Section: Discussionmentioning

confidence: 99%

Section: Research Articlementioning

confidence: 99%

River delta shoreline reworking and erosion in the Mediterranean and Black Seas: the potential roles of fluvial sediment starvation and other factors

Besset

Anthony

Sabatier

2017

Elementa: Science of the Anthropocene

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“…In addition, samples with an origin other than loess were investigated. Sample coded as M#6 is quartz extracted from a carbonate eolianite from Eivissa (see del Valle et al, 2016 for the geological context), sample S1 is eolian sand from the Danube Delta (Preoteasa et al, 2016). Also, samples of marine sediments from the Eemian site at Sula in Russia (Murray et al, 2007), a sample of sand at Gammelmarke in southern Jutland (Murray and Funder, 2003) and sand from Skagen , both in Denmark, and a sample of sand from Zwolle, Netherlands (Buylaert et al, 2009(Buylaert et al, , 2012 have been included in the analysis.…”

Section: Samples Instrumentation and Measurement Protocolmentioning

confidence: 99%

On the importance of grain size in luminescence dating using quartz

Timar-Gabor

Buylaert

Guralnik

et al. 2017

Radiation Measurements

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h i g h l i g h t sDiscrepancy between quartz SAR-OSL ages obtained on fine and coarse grains. Dose response curve adequately fitted by a sum of two saturating exponentials. Isothermal decay fitted by a single exponential. Clear dependency between the saturation characteristics (D 0 s) and the quartz grain size. No correlation between the 2 D 0 value and the maximum attainable accurate equivalent dose. a r t i c l e i n f o a b s t r a c tThere are two major problems commonly encountered when applying Optically Stimulated Luminescence (OSL) dating in the high dose range: (i) age discrepancy between different grain sizes, and (ii) age underestimation. A marked and systematic discrepancy between fine-grain (4e11 mm) and coarse-grain (63e90 mm) quartz single aliquot regeneration protocol (SAR) ages has been reported previously for Romanian and Serbian loess >40 ka (D e of~100 Gy), generally with fine-grain ages underestimating the depositional age. In this paper, we show a similar age pattern for two grain size fractions from Chinese loess, thus pointing to a potential worldwide phenomenon. While age underestimation is often attributed to signal saturation problems, this is not the case for fine grain material, which saturates at higher doses than coarse grains, yet begins to underestimate true ages earlier. Here we examine the dose response curves of quartz from different sedimentary contexts around the world, using a range of grain sizes (diameters of 4e11 mm, 11e30 mm, 35e50 mm, 63e90 mm, 90e125 mm, 125e180 mm, and 180 e250 mm). All dose response curves can be adequately described by a sum of two saturating exponential functions, whose saturation characteristics (D 0 values) are clearly anticorrelated with grain diameter (4) through an inverse square root relationship, D 0 ¼ A/√4, where A is a scaling factor. While the mechanism behind this grain-size dependency of saturation characteristics still needs to be understood, our results show that the observation of an extended SAR laboratory dose response curve does not necessarily enable high doses to be recorded accurately, or provide a corresponding extended age range.

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“…The lagoon's shallow waters sit atop mouth bar deposits that have formed from sediment settling from fluvial jet expansion at the Sfantu Gheorghe mouth before the emergence of the Sacalin barrier. It is slowly being infilled from north to south through the formation of a bayhead delta from sediments supplied by a secondary branch of the Sfantu Gheorghe (Preoteasa et al ., ).…”

Section: Study Areamentioning

confidence: 97%

“…The shoreface fronting the northern and central units of the spit is convex–concave, eroding over the long term, with a noticeable lower sloping platform situated at around −6 m. This shoreface is the result of barrier transgression over the previous mouth‐bar deposits of the Sfantu Gheorghe (Preoteasa et al ., ). Recent measurements have shown the prevalence of transverse nearshore bars spaced a few hundred meters apart, present down to −8 m depth.…”

Section: Study Areamentioning

confidence: 97%

The formation and closure of the Big Breach of Sacalin spit associated with extreme shoreline retreat and shoreface erosion

Zăinescu

Vespremeanu‐Stroe

Tătui

2019

Earth Surf Processes Landf

Self Cite

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We document a case of exceptionally large natural breaching of a sandy spit (Sacalin spit, Danube Delta) using multiannual to seasonal surveys of topography and bathymetry on successive cross-barrier and shoreface profiles, LiDAR data, satellite imagery, and wind and wave data.The large breach, which quickly reached 3.4 km in May 2014, is attributed to morphological preconditioning of the narrow (50-150 m) barrier, which was susceptible to breaching even during moderate storm conditions. The event switched the barrier's decadal evolution from low cross-shore transport to high cross-shore transport over the barrier, which is an order of magnitude larger than during the non-breach period. Upper shoreface erosion, as indicated by the extensive erosion down to À4 m, indicates that this zone is a significant source for the rebuilding of the barrier. Barrier recovery and widening trigger a negative feedback which limits the back-barrier sediment transfer. As a result, back-barrier deposition decreases whilst the barrier aggradation through overwash becomes more frequent.The Big Breach (TBB) closed naturally in three years. The very high deposition rate of sediment in the breach is a testimony of the high sediment volumes supplied by the longshore transport and the high sediment released through shoreface retreat, and resulted in widening the barrier to a maximum of 1 km. Since the newly-formed barrier shoreline retreated 500 m, this reveals that barrier breaching is an important mechanism which significantly accelerates the landward migration of the barrier system and is a proof of the highly non-linear morphodynamics involved in the barrier island translation.

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The evolution of an asymmetric deltaic lobe (Sf. Gheorghe, Danube) in association with cyclic development of the river-mouth bar: Long-term pattern and present adaptations to human-induced sediment depletion

Cited by 40 publications

References 25 publications

River delta shoreline reworking and erosion in the Mediterranean and Black Seas: the potential roles of fluvial sediment starvation and other factors

River delta shoreline reworking and erosion in the Mediterranean and Black Seas: the potential roles of fluvial sediment starvation and other factors

On the importance of grain size in luminescence dating using quartz

The formation and closure of the Big Breach of Sacalin spit associated with extreme shoreline retreat and shoreface erosion

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