Articles | Volume 21, issue 6
https://doi.org/10.5194/os-21-3291-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/os-21-3291-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
03 Dec 2025
Research article |
| 03 Dec 2025
| 03 Dec 2025
Modelling river-sea continuum: the case of the Danube Delta
Christian Ferrarin
CORRESPONDING AUTHOR
CNR – National Research Council of Italy, ISMAR – Marine Sciences Institute, Venice, Italy
Debora Bellafiore
CNR – National Research Council of Italy, ISMAR – Marine Sciences Institute, Venice, Italy
Alejandro Paladio Hernandez
CNR – National Research Council of Italy, ISMAR – Marine Sciences Institute, Venice, Italy
Irina Dinu
National Institute of Marine Geology and Geoecology – GeoEcoMar, Bucharest, Romania
Adrian Stanica
National Institute of Marine Geology and Geoecology – GeoEcoMar, Bucharest, Romania
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Short summary
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Relative sea level in Venice rose by about 2.5 mm/year in the past 150 years due to the combined effect of subsidence and mean sea-level rise. We estimate the likely range of mean sea-level rise in Venice by 2100 due to climate changes to be between about 10 and 110 cm, with an improbable yet possible high-end scenario of about 170 cm. Projections of subsidence are not available, but historical evidence demonstrates that they can increase the hazard posed by climatically induced sea-level rise.
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Short summary
Short summary
In this review we describe the factors leading to the extreme water heights producing the floods of Venice. We discuss the different contributions, their relative importance, and the resulting compound events. We highlight the role of relative sea level rise and the observed past and very likely future increase in extreme water heights, showing that they might be up to 160 % higher at the end of the 21st century than presently.
Christian Ferrarin, Marco Bajo, and Georg Umgiesser
Geosci. Model Dev., 14, 645–659, https://doi.org/10.5194/gmd-14-645-2021, https://doi.org/10.5194/gmd-14-645-2021, 2021
Short summary
Short summary
The problem of the optimization of ocean monitoring networks is tackled through the implementation of data assimilation techniques in a numerical model. The methodology has been applied to the tide gauge network in the Lagoon of Venice (Italy). The data assimilation methods allow identifying the minimum number of stations and their distribution that correctly represent the lagoon's dynamics. The methodology is easily exportable to other environments and can be extended to other variables.
Cited articles
Androsov, A., Fofonova, V., Kuznetsov, I., Danilov, S., Rakowsky, N., Harig, S., Brix, H., and Wiltshire, K. H.: FESOM-C v.2: coastal dynamics on hybrid unstructured meshes, Geosci. Model Dev., 12, 1009–1028, https://doi.org/10.5194/gmd-12-1009-2019, 2019. a
Bajo, M., Ferrarin, C., Dinu, I., Stanica, A., and Umgiesser, G.: The circulation near the Romanian coast and the Danube Delta modelled with finite elements, Cont. Shelf Res., 78, 62–74, https://doi.org/10.1016/j.csr.2014.02.006, 2014. a, b
Barsi, J., Barker, J., and Schott, J.: An atmospheric correction parameter calculator for a single thermal band earth-sensing instrument IGARSS 2003, in: Proceedings of the 2003 IEEE International Geoscience and Remote Sensing Symposium (IEEE Cat. No. 03CH37477), 5, 3014–3016, 2003. a
Bellafiore, D., Mc Kiver, W., Ferrarin, C., and Umgiesser, G.: The importance of modeling nonhydrostatic processes for dense water reproduction in the southern Adriatic Sea, Ocean Model., 125, 22–28, https://doi.org/10.1016/j.ocemod.2018.03.001, 2018. a
Bellafiore, D., Ferrarin, C., Braga, F., Zaggia, L., Maicu, F., Lorenzetti, G., Manfè, G., Brando, V., and De Pascalis, F.: Coastal mixing in multiple-mouth deltas: a case study in the Po Delta, Italy, Estuarine Coastal Shelf Sci., 226, 106254, https://doi.org/10.1016/j.ecss.2019.106254, 2019. a, b
Bellafiore, D., Ferrarin, C., Maicu, F., Manfé, G., Lorenzetti, G., Umgiesser, G., Zaggia, L., and Valle-Levinson, A.: Saltwater intrusion in a Mediterranean delta under a changing climate, J. Geophys. Res.-Oceans, 126, e2020JC016437, https://doi.org/10.1029/2020JC016437, 2021. a
Bloesch, J., Lenhardt, M., and Ionescu, C.: Chapter 8 – Hydromorphological alterations and overexploitation of aquatic resources, in: The Danube River and The Western Black Sea Coast, edited by: Bloesch, J., Cyffka, B., Hein, T., Sandu, C., and Sommerwerk, N., Ecohydrology from Catchment to Coast, 147–164, Elsevier, https://doi.org/10.1016/B978-0-443-18686-8.00001-9, 2025. a
Bricheno, L. M., Wolf, J., and Islam, S.: Tidal intrusion within a mega delta: An unstructured grid modelling approach, Estuarine Coastal Shelf Sci., 182, 12–26, https://doi.org/10.1016/j.ecss.2016.09.014, 2016. a
Burchard, H. and Petersen, O.: Models of turbulence in the marine environment – a comparative study of two equation turbulence models, J. Mar. Syst., 21, 29–53, https://doi.org/10.1016/S0924-7963(99)00004-4, 1999. a
Chen, C., Liu, H., and Beardsley, R.: An unstructured grid, finite-volume, three-dimensional, primitive equations ocean model: application to coastal ocean and estuaries, J. Atmos. Ocean. Tech., 20, 159–186, https://doi.org/10.1175/1520-0426(2003)020<0159:AUGFVT>2.0.CO;2, 2003. a
Constantinescu, A. M., Tyler, A. N., Stanica, A., Spyrakos, E., Hunter, P. D., Catianis, I., and Panin, N.: A century of human interventions on sediment flux variations in the Danube-Black Sea transition zone, Front. Mar. Sci., 10, https://doi.org/10.3389/fmars.2023.1068065, 2023. a, b, c
Cucco, A., Umgiesser, G., Ferrarin, C., Perilli, A., Melaku Canu, D., and Solidoro, C.: Eulerian and lagrangian transport time scales of a tidal active coastal basin, Ecol. Model., 220, 913–922, https://doi.org/10.1016/j.ecolmodel.2009.01.008, 2009. a
Deltares: Delft3D Flexible Mesh Suite, Deltares, Tech. rep., Deltares, https://www.deltares.nl/en/software-and-data/products/delft3d-flexible-mesh-suite (last access: 25 October 2025), 2023. a
Dan, S., Stive, M., Walstra, D.-J. R., and Panin, N.: Wave climate, coastal sediment budget and shoreline changes for the Danube Delta, Mar. Geol., 262, 39–49, https://doi.org/10.1016/j.margeo.2009.03.003, 2009. a
De Pascalis, F., Urbinati, E., Aalifar, A., Alcazar, L. A., Arpaia, L., Bajo, M., Barbanti, A., Barbariol, F., Bastianini, M., Bellafiore, D., Bellati, F., Benetazzo, A., Bologna, G., Bonaldo, D., Bongiorni, L., Braga, F., Brando, V. E., Brunetti, F., Caccavale, M., Camatti, E., Campostrini, P., Cantoni, C., Canu, D., Capotondi, L., Cassin, D., Castelli, G., Celussi, M., Correggiari, A., Cozzi, S., Dabalà, C., Davison, S., Fadini, A., Falcieri, F. M., Falcini, F., Ferrarin, C., Foglini, F., Gissi, E., Ghezzo, M., Grande, V., Guarneri, I., Lanzoni, A., Laurent, C., Lorenzetti, G., Madricardo, F., Manfè, G., Mc Kiver, W., Menegon, S., Moschino, V., Nesto, N., Petrizzo, A., Pomaro, A., Ravaioli, M., Remia, A., Riminucci, F., Rosina, A., Rosati, G., Santoleri, R., Scarpa, G., Scroccaro, I., Stanghellini, G., Solidoro, C., and Umgiesser, G.: The DANUBIUS-RI Supersite of Po Delta and North Adriatic Lagoons: a living lab on transitional environments in the Adriatic Sea, Estuarine Coastal Shelf Sci., 324, 109453, https://doi.org/10.1016/j.ecss.2025.109453, 2025. a
Dinu, I., Umgiesser, G., Bajo, M., De Pascalis, F., Stanica, A., Pop, C., Dimitriu, R., Nichersu, I., and Constantinescu, A.: Modelling of the response of the Razelm Sinoie lagoon system to physical forcing, GeoEcoMarina, Zenodo, 21, 5–18, https://doi.org/10.5281/zenodo.45064, 2015. a
EMODnet Bathymetry Consortium: EMODnet Digital Bathymetry (DTM 2022), EMODnet Bathymetry Consortium [data set], https://doi.org/10.12770/ff3aff8a-cff1-44a3-a2c8-1910bf109f85, 2022. a, b
Feizabadi, S., Li, C., and Hiatt, M.: Response of river delta hydrological connectivity to changes in river discharge and atmospheric frontal passage, Front. Mar. Sci., 11, https://doi.org/10.3389/fmars.2024.1387180, 2024. a, b
Ferrarin, C., Ghezzo, M., Umgiesser, G., Tagliapietra, D., Camatti, E., Zaggia, L., and Sarretta, A.: Assessing hydrological effects of human interventions on coastal systems: numerical applications to the Venice Lagoon, Hydrol. Earth Syst. Sci., 17, 1733–1748, https://doi.org/10.5194/hess-17-1733-2013, 2013. a, b
Ferrarin, C., Bajo, M., Bellafiore, D., Cucco, A., De Pascalis, F., Ghezzo, M., and Umgiesser, G.: Toward homogenization of Mediterranean lagoons and their loss of hydrodiversity, Geophys. Res. Lett., 41, 5935–5941, https://doi.org/10.1002/2014GL060843, 2014. a
Ferrarin, C., Bellafiore, D., Sannino, G., Bajo, M., and Umgiesser, G.: Tidal dynamics in the inter-connected Mediterranean, Marmara, Black and Azov seas, Prog. Oceanogr., 161, 102–115, https://doi.org/10.1016/j.pocean.2018.02.006, 2018. a
Ferrarin, C., Davolio, S., Bellafiore, D., Ghezzo, M., Maicu, F., Drofa, O., Umgiesser, G., Bajo, M., De Pascalis, F., Malguzzi, P., Zaggia, L., Lorenzetti, G., Manfè, G., and Mc Kiver, W.: Cross-scale operational oceanography in the Adriatic Sea, J. Oper. Oceanogr., 12, 86–103, https://doi.org/10.1080/1755876X.2019.1576275, 2019. a
Ferrarin, C., Penna, P., Penna, A., Špada, V., Ricci, F., Bilić, J., Krzelj, M., Ordulj, M., Sikoronja, M., Duračić, I., Iagnemma, L., Bućan, M., Baldrighi, E., Grilli, F., Moro, F., Casabianca, S., Bolognini, L., and Marini, M.: Modelling the quality of bathing waters in the Adriatic Sea, Water, 13, 1525, https://doi.org/10.3390/w13111525, 2021. a
Fong, D. A. and Geyer, W. R.: Response of a river plume during an upwelling favorable wind event, J. Geophys. Res.-Oceans, 106, 1067–1084, https://doi.org/10.1029/2000JC900134, 2001. a
Fong, D. A. and Geyer, W. R.: The alongshore transport of freshwater in a surface-trapped river plume, J. Phys. Oceanogr., 32, 957–972, https://doi.org/10.1175/1520-0485(2002)032<0957:TATOFI>2.0.CO;2, 2002. a
Frank, G., Funk, A., Becker, I., Schneider, E., and Egger, G.: Chapter 16 – The key role of floodplains in nature conservation: How to improve the current status of biodiversity?, in: The Danube River and The Western Black Sea Coast, edited by Bloesch, J., Cyffka, B., Hein, T., Sandu, C., and Sommerwerk, N., Ecohydrology from Catchment to Coast, 335–364, Elsevier, https://doi.org/10.1016/B978-0-443-18686-8.00008-1, 2025. a
Garvine, R. W.: A dynamical system for classifying buoyant coastal discharges, Cont. Shelf Res., 15, 1585–1596, https://doi.org/10.1016/0278-4343(94)00065-U, 1995. a
Geuzaine, C. and Remacle, J.-F.: Gmsh: A 3-D finite element mesh generator with built-in pre- and post-processing facilities, Int. J. Numer. Methods Eng., 79, 1309–1331, https://doi.org/10.1002/nme.2579, 2009. a
Giosan, L., Donnelly, J. P., Constantinescu, S., Filip, F., Ovejanu, I., Vespremeanu-Stroe, A., Vespremeanu, E., and Duller, G. A.: Young Danube delta documents stable Black Sea level since the middle Holocene: Morphodynamic, paleogeographic, and archaeological implications, Geology, 34, 757–760, https://doi.org/10.1130/G22587.1, 2006. a
Hariharan, J., Wright, K., Moodie, A., Tull, N., and Passalacqua, P.: Impacts of human modifications on material transport in deltas, Earth Surf. Dynam., 11, 405–427, https://doi.org/10.5194/esurf-11-405-2023, 2023. a
Hersbach, H., Bell, B., Berrisford, P., Hirahara, S., Horànyi, A., Munoz-Sabater, J., Nicolas, J., Peubey, C., Radu, R., Schepers, D., Simmons, A., Soci, C., Abdalla, S., Abellan, X., Balsamo, G., Bechtold, P., Biavati, G., Bidlot, J., Bonavita, M., De Chiara, G., Dahlgren, P., Dee, D., Diamantakis, M., Dragani, R., Flemming, J., Forbes, R., Fuentes, M., Geer, A., Haimberger, L., Healy, S., Hogan, R. J., Hólm, E., Janisková, M., Keeley, S., Laloyaux, P., Lopez, P., Lupu, C., Radnoti, G., de Rosnay, P., Rozum, I., Vamborg, F., Villaume, S., and Thépaut, J.-N.: The ERA5 global reanalysis, Q. J. Roy. Meteor. Soc., 146, 1999–2049, https://doi.org/10.1002/qj.3803, 2020. a
Horner-Devine, A. R., Hetland, R. D., and MacDonald, D. G.: Mixing and Transport in Coastal River Plumes, Annu. Rev. Fluid Mech., 47, 569–594, https://doi.org/10.1146/annurev-fluid-010313-141408, 2015. a, b
Kjerfve, B.: Comparative oceanography of coastal lagoons, in: Estuarine Variability, edited by D. A. Wolfe, 63–81, Academic Press, New York, USA, https://doi.org/10.1016/B978-0-12-761890-6.50009-5, 1986. a
Kolb, P., Zorndt, A., Burchard, H., Gräwe, U., and Kösters, F.: Modelling the impact of anthropogenic measures on saltwater intrusion in the Weser estuary, Ocean Sci., 18, 1725–1739, https://doi.org/10.5194/os-18-1725-2022, 2022. a
Li, M., Najjar, R. G., Kaushal, S., Mejia, A., Chant, R. J., Ralston, D. K., Burchard, H., Hadjimichael, A., Lassiter, A., and Wang, X.: The emerging global threat of salt contamination of water supplies in tidal rivers, Environ. Sci. Technol. Lett., 12, 881–892, https://doi.org/10.1021/acs.estlett.5c00505, 2025. a
Lima, L., Aydogdu, A., Escudier, R., Masina, S., Ciliberti, S. A., Azevedo, D., Peneva, E. L., Causio, S., Cipollone, A., Clementi, E., Cretí, S., Stefanizzi, L., Lecci, R., Palermo, F., Coppini, G., Pinardi, N., and Palazov, A.: Black Sea Physical Reanalysis (CMEMS BLK-Physics, E3R1 system) (Version 1), Copernicus Monitoring Environment Marine Service (CMEMS) [data set], https://doi.org/10.25423/CMCC/BLKSEA_MULTIYEAR_PHY_ 007_004, 2020. a, b, c
Maicu, F., De Pascalis, F., Ferrarin, C., and Umgiesser, G.: Hydrodynamics of the Po River-Delta-Sea system, J. Geophys. Res.-Oceans, 123, 6349–6372, https://doi.org/10.1029/2017JC013601, 2018. a, b, c
Maselli, V. and Trincardi, F.: Man made deltas, Sci. Rep., 3, 1926, https://doi.org/10.1038/srep01926, 2013. a
Miladinova, S., Stips, A., Macias Moy, D., and Garcia-Gorriz, E.: Pathways and mixing of the north western river waters in the Black Sea, Estuarine Coastal Shelf Sci., 236, 106630, https://doi.org/10.1016/j.ecss.2020.106630, 2020. a, b
Newton, A., Mistri, M., Pérez-Ruzafa, A., and Reizopoulou, S.: Editorial: Ecosystem services, biodiversity, and water quality in transitional ecosystems, Frontiers in Ecology and Evolution, 11, https://doi.org/10.3389/fevo.2023.1136750, 2023. a
Nichersu, I., Livanov, O., Mierlǎ, M., Trifanov, C., Simionov, M., Lupu, G., Ibram, O., Burada, A., Despina, C., Covaliov, S., Doroftei, M., Doroşencu, A., Bolboacǎ, L., Nǎstase, A., Ene, L., and Balaican, D.: Chapter 6 – The Danube Delta – The link between the Danube River and the Black Sea, in: The Danube River and The Western Black Sea Coast, edited by Bloesch, J., Cyffka, B., Hein, T., Sandu, C., and Sommerwerk, N., Ecohydrology from Catchment to Coast, 107–122, Elsevier, https://doi.org/10.1016/B978-0-443-18686-8.00002-0, 2025. a, b
Panin, N.: Impact of global changes on geo-environmental and coastal zone state of the Black Sea, GeoEcoMarina, 1, 7–23, 1996. a
Panin, N.: Global changes, sea level rise and the Danube Delta: risks and responses, GeoEcoMarina, 4, 19–29, 1999. a
Passalacqua, P.: The Delta Connectome: A network-based framework for studying connectivity in river deltas, Geomorphology, 277, 50–62, https://doi.org/10.1016/j.geomorph.2016.04.001, 2017. a
Payo-Payo, M., Bricheno, L. M., Dijkstra, Y. M., Cheng, W., Gong, W., and Amoudry, L. O.: Multiscale temporal response of salt intrusion to transient river and ocean forcing, J. Geophys. Res.-Oceans, 127, e2021JC017523, https://doi.org/10.1029/2021JC017523, 2022. a
Pein, J., Staneva, J., Mayer, B., Palmer, M., and Schrum, C.: A framework for estuarine future sea-level scenarios: Response of the industrialised Elbe estuary to projected mean sea level rise and internal variability, Frontiers in Marine Science, 10, https://doi.org/10.3389/fmars.2023.1102485, 2023. a
Pekárová, P., Mèszáros, J., Miklánek, P., Pekár, J., Prohaska, S., and Ilić, A.: Long-term runoff variability analysis of rivers in the Danube basin, Acta Horticulturae et Regiotecturae, 24, 37–44, https://doi.org/10.2478/ahr-2021-0008, 2021. a
Pérez-Ruzafa, A., Pérez-Ruzafa, I. M., Newton, A., and Marcos, C.: Chapter 15 – Coastal Lagoons: Environmental Variability, Ecosystem Complexity, and Goods and Services Uniformity, in: Coasts and Estuaries, edited by Wolanski, E., Day, J. W., Elliott, M., and Ramachandran, R., 253–276, Elsevier, https://doi.org/10.1016/B978-0-12-814003-1.00015-0, 2019. a
Probst, E. and Mauser, W.: Climate Change Impacts on Water Resources in the Danube River Basin: A Hydrological Modelling Study Using EURO-CORDEX Climate Scenarios, Water, 15, https://doi.org/10.3390/w15010008, 2023. a
Schimanke, S., Ridal, M., Le Moigne, P., Berggren, L., Undén, P., Randriamampianina, R., Andrea, U., Bazile, E., Bertelsen, A., Brousseau, P., Dahlgren, P., Edvinsson, L., El Said, A., Glinton, M., Hopsch, S., Isaksson, L., Mladek, R., Olsson, E., Verrelle, A., and Wang, Z. Q.: CERRA sub-daily regional reanalysis data for Europe on single levels from 1984 to present, Copernicus Climate Change Service (C3S) Climate Data Store (CDS) [data set], https://doi.org/10.24381/cds.622a565a, 2021. a, b
Shen, Y., Jia, H., Li, C., and Tang, J.: Numerical simulation of saltwater intrusion and storm surge effects of reclamation in Pearl River Estuary, China, Applied Ocean Research, 79, 101–112, https://doi.org/10.1016/j.apor.2018.07.013, 2018. a
Simpson, J. H., Bos, W., Schirmer, F., Souza, A., Rippeth, T., Jones, S., and Hydes, D.: Periodic stratification in the Rhine ROFI in the North Sea, Oceanologica Acta, 16, 23–32, 1993. a
Stolz, R., Mauser, W., and Probst, E.: Chapter 10 – Climate change-specific consequences for the Danube River Basin and the Black Sea Coast, in: The Danube River and The Western Black Sea Coast, edited by Bloesch, J., Cyffka, B., Hein, T., Sandu, C., and Sommerwerk, N., Ecohydrology from Catchment to Coast, 195–222, Elsevier, https://doi.org/10.1016/B978-0-443-18686-8.00012-3, 2025. a
Telemac-Mascaret, O.: TELEMAC-3D Theory guide, Tech. rep., http://www.opentelemac.org/ (last access: 25 October 2025), 2022. a
Thanh, V. Q., Roelvink, D., van der Wegen, M., Reyns, J., Kernkamp, H., Van Vinh, G., and Linh, V. T. P.: Flooding in the Mekong Delta: the impact of dyke systems on downstream hydrodynamics, Hydrol. Earth Syst. Sci., 24, 189–212, https://doi.org/10.5194/hess-24-189-2020, 2020. a, b
Umgiesser, G.: The impact of operating the mobile barriers in Venice (MOSE) under climate change, J. Nat. Conserv., 54, 125783, https://doi.org/10.1016/j.jnc.2019.125783, 2020. a
Umgiesser, G., Melaku Canu, D., Cucco, A., and Solidoro, C.: A finite element model for the Venice Lagoon. Development, set up, calibration and validation, J. Mar. Syst., 51, 123–145, https://doi.org/10.1016/j.jmarsys.2004.05.009, 2004. a
Umgiesser, G., Ferrarin, C., Cucco, A., De Pascalis, F., Bellafiore, D., Ghezzo, M., and Bajo, M.: Comparative hydrodynamics of 10 Mediterranean lagoons by means of numerical modeling, J. Geophys. Res.-Oceans, 119, 2212–2226, https://doi.org/10.1002/2013JC009512, 2014. a, b, c
Umgiesser, G., Ferrarin, C., Bajo, M., Bellafiore, D., Cucco, A., De Pascalis, F., Ghezzo, M., Mc Kiver, W., and Arpaia, L.: Hydrodynamic modelling in marginal and coastal seas – The case of the Adriatic Sea as a permanent laboratory for numerical approach, Ocean Model., 179, 102123, https://doi.org/10.1016/j.ocemod.2022.102123, 2022. a, b, c, d, e, f
Umgiesser, G., Arpaia, L., CeliaLaurent, gmicaletto, Ferrarin, C., shyfem-cm, Bajo, M., jalessandri, fivan, Pinsky, A., Epicoco, I., Ghezzo, M., Chegini, T., and dbellafiore: georgu/shyfemcm-ismar: Ebbe edition (VERS_8_2_6), Zenodo [code], https://doi.org/10.5281/zenodo.17721804, 2025. a
Vallaeys, V., Kärnä, T., Delandmeter, P., Lambrechts, J., Baptista, A. M., Deleersnijder, E., and Hanert, E.: Discontinuous Galerkin modeling of the Columbia River's coupled estuary-plume dynamics, Ocean Model., 124, 111–124, https://doi.org/10.1016/j.ocemod.2018.02.004, 2018. a, b
Valle-Levinson, A.: Contemporary Issues in Estuarine Physics, Cambridge University Press, https://doi.org/10.1017/CBO9780511676567, 2010. a
van de Wal, R., Melet, A., Bellafiore, D., Camus, P., Ferrarin, C., Oude Essink, G., Haigh, I. D., Lionello, P., Luijendijk, A., Toimil, A., Staneva, J., and Vousdoukas, M.: Sea Level Rise in Europe: Impacts and consequences, in: Sea Level Rise in Europe: 1st Assessment Report of the Knowledge Hub on Sea Level Rise (SLRE1), edited by: van den Hurk, B., Pinardi, N., Kiefer, T., Larkin, K., Manderscheid, P., and Richter, K., Copernicus Publications, State Planet, 3-slre1, 5, https://doi.org/10.5194/sp-3-slre1-5-2024, 2024. a
van Gils, J., Loos, S., and Boisgontier, H.: Simulated fluxes of water, heat, nutrients, fine sediment for 13 large rivers to the Black Sea 2011–2020, Zenodo [data set], https://doi.org/10.5281/zenodo.15675190, 2025. a, b, c
Vespremeanu-Stroe, A., Preoteasa, L., Hanganu, D., Brown, T., Bîrzescu, I., Toms, P., and Timar-Gabor, A.: The impact of the Late Holocene coastal changes on the rise and decay of the ancient city of Histria (Southern Danube delta), Quaternary International, 293, 245–256, https://doi.org/10.1016/j.quaint.2012.11.039, 2013. a
Warrick, J. A. and Farnsworth, K. L.: Coastal river plumes: Collisions and coalescence, Prog. Oceanogr., 151, 245–260, https://doi.org/10.1016/j.pocean.2016.11.008, 2017. a
Zhang, A. and Yu, X.: Development of a land–river–ocean coupled model for compound floods jointly caused by heavy rainfall and storm surges in large river delta regions, Hydrol. Earth Syst. Sci., 29, 2505–2520, https://doi.org/10.5194/hess-29-2505-2025, 2025. a
Zhang, Y. J., Ye, F., Stanev, E. V., and Grashorn, S.: Seamless cross-scale modeling with SCHISM, Ocean Model., 102, 64–81, https://doi.org/10.1016/j.ocemod.2016.05.002, 2016. a
Zhu, J., Cheng, X., Li, L., Wu, H., Gu, J., and Lyu, H.: Dynamic mechanism of an extremely severe saltwater intrusion in the Changjiang estuary in February 2014, Hydrol. Earth Syst. Sci., 24, 5043–5056, https://doi.org/10.5194/hess-24-5043-2020, 2020. a
Short summary
This paper investigates the hydrodynamic processes among the interconnected water bodies (river branches, lagoons, and the coastal sea) that together form the Danube Delta river-sea continuum. To achieve this, we implemented the SHYFEM (System of HydrodYnamic Finite Element Modules) model across the entire Danube Delta. The model was applied to investigate the distribution of water among river branches, coastal dynamics in front of the delta, the renewal capacity of the lagoons, and the potential impacts of lagoon-sea reconnection solutions.
This paper investigates the hydrodynamic processes among the interconnected water bodies (river...
