Numerical modelling of sediment transport in the Adriatic Sea

Abstract. A new sediment transport model, considering currents, tides and waves is presented for the Adriatic Sea basin. The simulations concentrate on the winter of 2002–2003 because of field data availability and interesting intermittent processes occurrence. A process oriented analysis is performed to investigate the impact that Sirocco and Bora wind regimes have on sediment transport. The comparisons of the simulations with the observed data show that the model is capable to capture the main dynamics of sediment transport along the Italian coasts and the sediment concentration within the water column. This latter can reach values up to several g L−1, especially within the first centimetres above the bottom. The sediments are transported mainly southwards along the Italian coasts, consistently with the known literature results, except during Sirocco wind events, which can be responsible for reversing the coastal circulation in the northern area of the basin, and consequently the sediment transport. The resuspension of sediments is also related to the specific wave regimes induced by Bora and Sirocco, the former inducing resuspension events near the coasts while the latter causing a more diffused resuspension regime in the Northern Adriatic basin. Beside the realistic representation of short timescales resuspension/deposition events due to storms, the model was also used to investigate persistent erosion or deposition areas in the Adriatic Sea. Two main depocenters were identified: one, very pronounced, in the surroundings of the Po river delta, and another one a few kilometres off the coast in front of the Ancona promontory. A third region of accumulation, even if less intense, was found to be offshore the southernmost limit of the Gargano region. On the contrary the whole western coast within a distance of a few kilometres from the shore was found to be subject to prevailing erosion. The comparison with observed accumulation and erosion data shows that the model captures well the main depocenters in the domain and the erosion within the very coastal belt of the western side of the basin, but seems to be too erosive in a few areas, in particular those where the contribution of sediment inflow to the sea of some minor but intermittently important rivers is not considered in a realistic way as input to the model.

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Modeling the Environmental Dynamics of the Northern Adriatic Sea with an explicit benthic-pelagic coupling.

10.5194/egusphere-egu21-10691 ◽

2021 ◽

Author(s):

Marco Zavatarelli ◽

Isabella Scroccaro ◽

Tomas Lovato

Keyword(s):

General Circulation ◽

Adriatic Sea ◽

Circulation Model ◽

Open Boundary ◽

Biogeochemical Model ◽

Northern Adriatic Sea ◽

Po River ◽

Northern Adriatic ◽

Benthic Pelagic Coupling ◽

The Impact

In the framework of the European Project H2020 "ODYSSEA" (Operating a network of integrated observatory systems in the Mediterranean SEA,&#160;http://odysseaplatform.eu/) a forecasting modeling system of the coupled physical and biogeochemical conditions&#160;of the Northern Adriatic Sea is under development.The modeling system consists of the on-line coupling of the European general circulation model - NEMO (Nucleus for European&#160;Modeling of the Ocean,&#160;https://www.nemo-ocean.eu/), with the marine biogeochemical model - BFM (Biogeochemical Flux Model,&#160;bfm-community.eu/). The biogeochemical component of the model includes the simulation of the biogeochemical processes of both water column and sediments and their coupling. The model is run for the first time in the Northern Adriatic Sea with an explicit benthic-pelagic coupling.The horizontal spatial discretization is defined by a rectangular grid of 315 &#215; 278 cells, having a horizontal resolution of about 800 m. The vertical resolution is defined at 2 m, with 48 z-levels regularly spaced. Currently the atmospheric forcing are the ECMWF 6hr analysis atmospheric fields. The river supplies of fresh water and nutrient salts consider the daily runoff of the Po river, while the other&#160;rivers within the study area are included as climatological values. The open boundary conditions of the modeling system come from the Copernicus Marine Environment Monitoring Service (CMEMS,&#160;http://marine.copernicus.eu/).In this work, the hindcast simulations encompassing the period 2000 &#8211; 2009 are validated against available observations from in situ and satellite platforms for sea surface temperature, chlorophyll-a and dissolved inorganic nutrients and, in order to evaluate the impact of a resolved benthic biogeochemical dynamics,&#160; compared against simulations results obtained utilising a simple benthic closure parameterisation.

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Folic acid in coastal waters of the Adriatic Sea

Marine and Freshwater Research ◽

10.1071/mf02044 ◽

2002 ◽

Vol 53 (8) ◽

pp. 1245 ◽

Cited By ~ 16

Author(s):

Marta Plavšić ◽

Senka Terzic ◽

Marijan Ahel ◽

C. M. G. van den Berg

Keyword(s):

Folic Acid ◽

Water Column ◽

Adriatic Sea ◽

Photosynthetic Pigment ◽

Northern Adriatic Sea ◽

Po River ◽

Northern Adriatic ◽

Vitamin B Group ◽

Two Parameters ◽

The Impact

The concentration of folic acid (FA), an important constituent of the vitamin B group, was determined over a period of 2 years in the water column of a small meromictic saline lake on the eastern Adriatic coast (Rogoznica Lake), as well as in the western part of the northern Adriatic Sea. The FA concentration was over the range of 0.1–13.5 nM in the oxic part of Rogoznica Lake, and 0.1–22 nM in the northern Adriatic, with a maximum of 22 nM in the upper layer of the water column, possibly caused by the impact of Po River freshets on the FA concentrations. A weak but statistically significant correlation was established between photosynthetic pigment zeaxanthin, a characteristic biomarker of cyanobacteria, and FA in the oxic layer of the Rogoznica Lake (r2 = 0.3967; n = 29; P < 0.01), indicating cyanobacteria as a possible source of FA in this ecosystem. A statistically significant correlation (r2 = 0.36; n = 18; P < 0.01) between the two parameters was also found for the surface layer of the northern Adriatic (0 m). However, a low contribution of cyanobacteria to the total photosynthetic biomass in the northern Adriatic, and a lack of correlation between FA and zeaxanthin in the deeper layers of the water column, suggested that cyanobacteria were probably not the main source of FA in these waters. A stronger relationship (r2�= 0.46; n = 16; P < 0.01) between FA and chlorophyll b was found for the top 10 m of the northern Adriatic, indicating green algae as one of the possible sources of FA.

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Reconstructing the baseline population structure of the exploited bivalve Arca noae in the Northern Adriatic Sea

10.5194/egusphere-egu21-7694 ◽

2021 ◽

Author(s):

Saskia Macharia ◽

Rafał Nawrot ◽

Michaela Berensmeier ◽

Ivo Gallmetzer ◽

Alexandra Haselmair ◽

...

Keyword(s):

Adriatic Sea ◽

Size Structure ◽

Anthropogenic Impacts ◽

Natural State ◽

Published Data ◽

Northern Adriatic Sea ◽

Important Species ◽

Northern Adriatic ◽

Shell Bed ◽

The Impact

The Northern Adriatic Sea is one of the most impacted ecosystems worldwide with a long history of anthropogenic impacts, ranging from overfishing and bottom trawling to eutrophication, deoxygenation and pollution. The impact of these multiple pressures on populations of economically important species is often difficult to evaluate due to paucity of long-term monitoring data. The edible bivalve Noah&#8217;s Ark shell (Arca noae L.) was intensively harvested in the eastern Adriatic Sea until 1949-1950 when it suffered a catastrophic population collapse due to unknown agents. The assessment of its subsequent recovery is hindered by the lack of data on the population size structure prior to that event. To reconstruct the natural baseline state of populations of A. noae before the onset of extensive harvesting, we studied fossil assemblages from two 1.5-m-long sediment cores collected in the southern Gulf of Trieste (off Piran, Slovenia), both recording the last ~9,500 years.The abundance and shell length of A. noae remained low in the lower part of the cores but increased strongly within the oyster-Arca shell bed corresponding to maximum flooding and early highstand sea-level phases (6,500-1,000 years ago). In contrasts, the top 8 cm of the core (the late highstand phase), marked by high concentration of pollutants and organic enrichment, contained only few and small (< 10 mm) A. noae shells. Moreover, no living individuals were found in grab samples taken from the two stations suggesting that the dense populations of A. noae, persisting there for several thousand years, were locally extirpated in the 20th century. To evaluate population recovery in other parts of the NE Adriatic, we compared the size distribution of fossil A. noae from the shell bed interval to the previously published data on living populations of this species sampled along Istrian peninsula between 1966 and 1978. Both fossil and extant populations were characterized by similar median size, modal size class and proportion of specimens > 50 mm (minimal legal landing size). These results suggest that within few decades after the 1949-1950 mass mortality event the size structure of populations of A. noae have largely returned to their earlier, natural state. The recovery was spatially variable, however, as attested by the decline of A. noae populations due to loss of suitable shell-bed habitats in the two studied stations off Piran.

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Seasonal and Interannual Trends of Oceanographic Parameters over 40 Years in the Northern Adriatic Sea in Relation to Nutrient Loadings Using the EMODnet Chemistry Data Portal

Water ◽

10.3390/w12082280 ◽

2020 ◽

Vol 12 (8) ◽

pp. 2280 ◽

Cited By ~ 1

Author(s):

Federica Grilli ◽

Stefano Accoroni ◽

Francesco Acri ◽

Fabrizio Bernardi Aubry ◽

Caterina Bergami ◽

...

Keyword(s):

Climate Changes ◽

Management Practices ◽

Adriatic Sea ◽

Nutrient Concentrations ◽

Data Series ◽

Mean Flow ◽

Northern Adriatic Sea ◽

Po River ◽

Northern Adriatic

Long-term data series (1971–2015) of physical and biogeochemical parameters were analyzed in order to assess trends and variability of oceanographic conditions in the northern Adriatic Sea (NAS), a mid-latitude shallow continental shelf strongly impacted by river discharges, human activities and climate changes. Interpolation maps and statistical models were applied to investigate seasonal and spatial variability, as well as decadal trends of temperature, salinity, chlorophyll-a and nutrients. This analysis shows that sea surface temperature increased by +0.36% year−1 over four decades. Annual mean flow of the Po River markedly changed due to the occurrence of periods of persistent drought, whereas the frequency of flow rates higher than 3000 m3 s−1 decreased between 2006 and 2015. Moreover, we observed a long-term decrease in surface phosphate concentrations in Po River water (−1.34% year−1) and in seawater (in summer −2.56% year−1) coupled, however, to a significant increase in nitrate concentration in seawater (+3.80% year−1) in almost all seasons. These changes indicate that the nutrient concentrations in the NAS have been largely modulated, in the last forty years, by the evolution of environmental management practices and of the runoff. This implies that further alteration of the marine environment must be expected as a consequence of the climate changes.

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Modeling the dynamics of sediment transport and resuspension in the northern Adriatic Sea

Journal of Geophysical Research Atmospheres ◽

10.1029/2001jc001303 ◽

2002 ◽

Vol 107 (C12) ◽

pp. 18-1-18-23 ◽

Cited By ~ 73

Author(s):

X. H. Wang ◽

N. Pinardi

Keyword(s):

Sediment Transport ◽

Adriatic Sea ◽

Northern Adriatic Sea ◽

Northern Adriatic

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Carbonate System and Acidification of the Adriatic Sea

10.5194/egusphere-egu2020-10977 ◽

2020 ◽

Author(s):

Valentina Turk ◽

Nina Bednarsek ◽

Jadran Faganeli ◽

Blaženka Gasparovic ◽

Michele Giani ◽

...

Keyword(s):

Mediterranean Sea ◽

Adriatic Sea ◽

Microbial Community Composition ◽

Aegean Sea ◽

Total Alkalinity ◽

The Black Sea ◽

Po River ◽

Saturation State ◽

Northern Adriatic ◽

The Mediterranean

Although the marginal seas represent only 7% of the total ocean area, the CO2 fluxes are intensive and important for the carbon budget, exposing to an intense process of anthropogenic ocean acidification (OA). A decline in pH, especially in the estuarine waters, results also from the eutrophication-induced acidification. The Adriatic Sea is currently a CO2 sink with an annual flux of approximately -1.2 to -3 mol C m-2 yr-1 which is twice as low compared to the net sink rates in the NW Mediterranean (-4 to -5 mol C m-2 yr-1). Based on the comparison of two winter cruises carried out in in the 25-year interval between 1983 and 2008, acidification rate of 0.003 pHT units yr&#8722;1 was estimated in the northern Adriatic which is similar to the Mediterranean open waters (with recent estimations of &#8722;0.0028 &#177; 0.0003 units pHT yr&#8722;1) and the surface coastal waters (-0.003 &#177; 0.001 and -0.0044 &#177; 0.00006 pHT units yr&#8722;1). The computed Revelle factor for the Adriatic Sea, with the value of about 10, indicates that the buffer capacity is rather high and that the waters should not be particularly exposed to acidification. Total alkalinity (TA) in the Adriatic (2.6-2.7 mM) is in the upper range of TA measured in the Mediterranean Sea because riverine inputs transport carbonates dissolved from the Alpine dolomites and karstic watersheds. The Adriatic Sea is the second sub-basin (319 Gmol yr-1), following the Aegean Sea (which receives the TA contribution from the Black Sea), that contribute to the riverine TA discharges into the Mediterranean Sea. About 60% of the TA inflow into the Adriatic Sea is attributed to the Po river discharge with TA of ~3 mM and TA decreases with increasing salinity. Saturation state indicates that the waters of the Adriatic are supersaturated with respect to calcite (&#937;Ca) and aragonite (&#937;Ar) throughout the year. However, saturation states are considerably lower in the bottom water layers, due to the prevalence of benthic remineralization processes in the stratification period. The seasonal changes of the chemical and environmental conditions and relatively small size of the Adriatic Sea area the microbial community composition, function (growth, enzymatic activity) and carbon and nitrogen biogeochemical cycles. Significant effects on calcifying organisms and phytoplankton are expected while the effects of possible OA on microbially-driven processes are not known yet.

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THE IMPACT OF BARRIER ISLAND DEGRADATION ON HURRICANE-INDUCED SEDIMENT TRANSPORT

Coastal Engineering Proceedings ◽

10.9753/icce.v36.papers.49 ◽

2018 ◽

pp. 49

Author(s):

Ke Liu ◽

Qin Chen ◽

Kelin Hu

Keyword(s):

Sediment Transport ◽

Storm Surge ◽

Coastal Wetland ◽

Transport Model ◽

Three Dimensional ◽

Barrier Islands ◽

Coastal Morphology ◽

Major Barrier ◽

Barataria Bay ◽

The Impact

Hurricanes are recognized as a strong forcing in changing coastal morphology by redistributing sediments. Barrier islands protect estuaries from storm surge and severe waves and confine water and sediment discharge into estuaries during a hurricane event. In this study, we developed a three-dimensional, fully coupled storm surge, waves, and sediment transport model. The impacts of barrier islands degradation on hurricane hydrodynamics and sediment dynamics were evaluated by comparing a hypothetical model configuration for four major barrier islands in Terrebonne Bay and Barataria Bay against a baseline configuration. With the hypothetical deterioration of barrier islands, model results showed that the sediment transport from the shelf to the estuary increased in Terrebonne Bay but decreased in Barataria Bay. In the simulations, most of the deposition on coastal wetland still originated from the bay even when the barrier islands were degraded.

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