The fate of coastal habitats in the Venice Lagoon from the sea level rise perspective

Salt marshes are biogeomorphic systems that provide important ecosystem services such as carbon sequestration and prevention of coastal erosion. These ecosystems are, however, threatened by increasing sea levels and human pressure. Improving current knowledge of salt-marsh response to changes in the environmental forcing is a key step to understand and predict salt-marsh evolution, especially under accelerated sea level rise scenarios and increasing human pressure. Towards this goal, we have analyzed field observations of marsh topographic changes and halophytic vegetation distribution with elevation collected over 20 years (between 2000 and 2019) in a representative marsh in the Venice lagoon (Italy).Our results suggest that: 1) on average, marsh elevation with respect to local mean sea level decreased , (i.e. the surface accretion rate was lower than the rate of sea level rise); 2) elevational frequency distributions are characteristic for different halophytic vegetation species, highlighting different ecological realized niches that change in time; 3) although the preferential elevations at which different species have changed in time, the sequence of vegetation species with increasing soil elevation was preserved and simply shifted upward; 4) we observed different vegetation migration rates for the different species, suggesting that the migration process is species-specific. In particular, vegetation species colonizing marsh edges (Juncus and Inula) migrated faster facing to changes in sea levels than Limonium and Spartina , while Sarcocornia was characterized by delayed migration in response to sea level changes. These results bear significant implications for long-term biogeomorphic evolution of tidal environments.

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Human impacts overwhelm the effects of sea-level rise on Basque coastal habitats (N Spain) between 1954 and 2004

Estuarine Coastal and Shelf Science ◽

10.1016/j.ecss.2009.07.010 ◽

2009 ◽

Vol 84 (4) ◽

pp. 453-462 ◽

Cited By ~ 30

Author(s):

Guillem Chust ◽

Ángel Borja ◽

Pedro Liria ◽

Ibon Galparsoro ◽

Marta Marcos ◽

...

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Human Impacts ◽

Coastal Habitats

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Assessing hydrological effects of human interventions on coastal systems: numerical applications to the Venice Lagoon

Hydrology and Earth System Sciences ◽

10.5194/hess-17-1733-2013 ◽

2013 ◽

Vol 17 (5) ◽

pp. 1733-1748 ◽

Cited By ~ 27

Author(s):

C. Ferrarin ◽

M. Ghezzo ◽

G. Umgiesser ◽

D. Tagliapietra ◽

E. Camatti ◽

...

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Venice Lagoon ◽

Mixing Processes ◽

Coastal System ◽

Water Renewal ◽

Internal Mixing ◽

Renewal Time ◽

Human Interventions ◽

The Impact

Abstract. The hydrological consequences of historical, contemporary and future human activities on a coastal system were investigated by means of numerical models. The changes in the morphology of the Lagoon of Venice during the last century result from the sedimentological response to the combined effects of human interventions on the environment and global changes. This study focuses on changes from 1927 to 2012 and includes the changes planned for the protection of the city of Venice from storm surges and exceptional tides under future sea level rise scenarios. The application of a hydrodynamic model allowed for the analysis of the morphological effects on the lagoon circulation, the interaction with the sea and the internal mixing processes. The absolute values of the exchange between the lagoon and sea increased from 1927 to 2002 (from 3900 to 4600 m3 s−1), while the daily fraction of lagoon water volume exchanged decreased. At the same time, the flattening of the lagoon and loss of morphological heterogeneity enhanced the internal mixing processes driven by the tide and wind, reducing thus the overall water renewal time from 11.9 days in 1927 to 10.8 days in 2002. Morphological changes during the last decade reduced the water exchange through the inlets and induced an increase of the basin-wide water renewal time of 0.5 day. In the future, Venice Lagoon will evolve to a more restricted environment due to sea level rise, which increases the lagoon volume, and periodical closure of the lagoon from the sea during flooding events, which reduces the communication with the open sea. Therefore, the flushing capacity of the lagoon will decrease considerably, especially in its central part. Furthermore, some considerations on the impact of the hydromorphological changes on the ecological dynamics are proposed.

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Regional scenarios of sea level rise and impacts on Basque (Bay of Biscay) coastal habitats, throughout the 21st century

Estuarine Coastal and Shelf Science ◽

10.1016/j.ecss.2009.12.021 ◽

2010 ◽

Vol 87 (1) ◽

pp. 113-124 ◽

Cited By ~ 26

Author(s):

Guillem Chust ◽

Ainhoa Caballero ◽

Marta Marcos ◽

Pedro Liria ◽

Carlos Hernández ◽

...

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

21St Century ◽

Bay Of Biscay ◽

Coastal Habitats

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Soil Accretionary Dynamics, Sea-Level Rise and the Survival of Wetlands in Venice Lagoon: A Field and Modelling Approach

Estuarine Coastal and Shelf Science ◽

10.1006/ecss.1999.0522 ◽

1999 ◽

Vol 49 (5) ◽

pp. 607-628 ◽

Cited By ~ 133

Author(s):

J.W Day ◽

J Rybczyk ◽

F Scarton ◽

A Rismondo ◽

D Are ◽

...

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Venice Lagoon ◽

Modelling Approach

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Aptitude of modern salt marshes to counteract relative sea-level rise, Venice Lagoon (Italy)

Geology ◽

10.1130/g31736.1 ◽

2011 ◽

Vol 39 (8) ◽

pp. 755-758 ◽

Cited By ~ 20

Author(s):

F. Rizzetto ◽

L. Tosi

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Salt Marshes ◽

Venice Lagoon ◽

Relative Sea Level ◽

Relative Sea Level Rise

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The Holocene influence on the future evolution of the Venice Lagoon tidal marshes

Communications Earth & Environment ◽

10.1038/s43247-021-00144-4 ◽

2021 ◽

Vol 2 (1) ◽

Author(s):

Claudia Zoccarato ◽

Cristina Da Lio

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Past History ◽

Venice Lagoon ◽

Tidal Marshes ◽

Future Evolution ◽

Sedimentation Dynamics ◽

History Of ◽

Present Rate

AbstractThe resilience of marsh ecosystems to expected sea-level rise is determined by a complex interplay of organic and inorganic sedimentation dynamics. Marshes have formed over past centuries to millennia and consist of extremely reactive bodies with sediments that can experience high compaction. Here we provide a quantification of the degree to which the past history of a salt marsh can affect its long-term evolution. A dataset of elevation dynamics was established in the Venice Lagoon (Italy) and interpreted using a physics-based model of deposition and large consolidation of newly deposited material. We found that the fate of low-lying tidal landscapes over the next century of accelerating sea-level rise will be highly dependent on compaction of soft, recently deposited soils. Our results imply that a sedimentation rate twice the present rate will be needed to counterbalance the expected sea-level rise.

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Assessing hydrological effects of human interventions on coastal systems: numerical applications to the Venice Lagoon

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-9-13839-2012 ◽

2012 ◽

Vol 9 (12) ◽

pp. 13839-13878 ◽

Cited By ~ 1

Author(s):

C. Ferrarin ◽

M. Ghezzo ◽

G. Umgiesser ◽

D. Tagliapietra ◽

E. Camatti ◽

...

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Venice Lagoon ◽

Water Volume ◽

Global Changes ◽

Coastal System ◽

Water Renewal ◽

Renewal Time ◽

Human Interventions ◽

The Impact

Abstract. The hydrological consequences of historical, contemporary and future human activities on a coastal system were investigated by means of numerical models. The changes in the morphology of the Lagoon of Venice during the last century result from the sedimentological response to the combined effects of human interventions on the environment and global changes. This study focuses on changes from 1927 to 2012 and includes the changes planned for the protection of the city of Venice from storm surges and exceptional tides under future sea level rise scenarios. The application of a hydrodynamic model to simulate the circulation of water masses and the transport of a passive tracer enabled the analysis of the morphodynamic effects on the lagoon circulation and the interaction with the sea. The absolute values of the exchange between the lagoon and sea increased from 1927 to 2002 (from 3900 to 4600 m3 s−1), while the daily fraction of lagoon water volume exchanged decreased. At the same time, the water renewal time shortened from 11.9 to 10.8 days. Morphological changes during the last decade induced an increase of the basin-wide water renewal time (from 10.8 to 11.3 days). In the future, Venice Lagoon will evolve to a more restricted environment due to sea level rise and periodical closure of the lagoon from the sea during flooding events. Simulated scenarios of sea level rise showed that under fall-winter conditions the water renewal time will increased considerably especially in the central part of the lagoon. Furthermore, some considerations on the impact of the hydromorphological changes on the ecological dynamics are proposed.

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Coastal flooding protection will change salt-marsh sedimentation dynamics

10.5194/egusphere-egu21-1639 ◽

2021 ◽

Author(s):

Davide Tognin ◽

Andrea D'Alpaos ◽

Marco Marani ◽

Luca Carniello

Keyword(s):

Salt Marsh ◽

Sea Level Rise ◽

Sea Level ◽

Storm Surge ◽

Sedimentation Rate ◽

Urban Areas ◽

Storm Surges ◽

Venice Lagoon ◽

Water Levels ◽

Sedimentation Dynamics

Coastal wetlands lie at the interface between submerged and emerged environments and therefore represent unique yet delicate ecosystems. Their existence, resulting from complex interactions between hydrodynamics and sediment dynamics, is challenged by increasing rates of sea-level rise, lowered fluvial sediment input as well as an increasing anthropogenic pressure. The future survival of these peculiar morphologies is becoming even more complicated, because of the construction and planning of coastal defence structures designed to protect urban areas from flooding. Important examples are the flood protection systems built to protect New Orleans (USA), the river Scheldt Estuary (The Netherlands) and Venice (Italy). In this context, understanding the physical processes on which coastal marshes are grounded and how engineering measures can alter them is of extreme importance in order to plan conservation interventions.To understand marsh sedimentation dynamics in flood-regulated environments, we investigated through field observations and modelling the effect of the storm-surge barrier designed to protect the city of Venice, the so-called Mo.S.E. system, which has in fact become operational since October 2020.Sedimentation measurements in different salt marshes of the Venice lagoon carried out in the period October 2018-October 2020 show that more than 70% of yearly sedimentation accumulates during storm-surge conditions, despite their short duration. Moreover, the sedimentation rate displays a highly non-linear increase with marsh inundation intensity, due to the interplay between higher water levels and greater suspended sediment concentration. Barrier operations during storm surges to avoid flooding of urban areas will reduce water levels and marsh inundation. Therefore, we computed sedimentation in a flood-regulated scenario for the same observation period, using the relation we obtained between tidal forcing and sedimentation rate. Our results show that some occasional closures during intense storm surges (70 hours/year on average) suffice to reduce the yearly sedimentation of the same order of magnitude of the relative sea-level rise rate experienced by the Venice lagoon during the last century (2.5 mm/y).We conclude that storm-surge barrier operations can dangerously reduce salt-marsh vertical accretion rate, thus challenging wetland survival in face of increasing sea-level rise.

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Natural Variability and Vertical Land Motion Contributions in the Mediterranean Sea-Level Records over the Last Two Centuries and Projections for 2100

Water ◽

10.3390/w11071480 ◽

2019 ◽

Vol 11 (7) ◽

pp. 1480 ◽

Cited By ~ 7

Author(s):

Vecchio ◽

Anzidei ◽

Serpelloni ◽

Florindo

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Venice Lagoon ◽

Natural Variability ◽

Climatic Data ◽

Sea Levels ◽

Vertical Land Motion ◽

Mode Decomposition ◽

Tidal Data ◽

Continuous Gps

We analyzed a set of geodetic data to investigate the contribution of local factors, namely the sea level natural variability (SLNV) and the vertical land motion (VLM), to the sea-level trend. The SLNV is analyzed through the Empirical Mode Decomposition (EMD) on tidal data (>60 years of recordings) and results are used to evaluate its effects on sea levels. The VLM is measured at a set of continuous GPS (cGPS) stations (>5 years of recordings), located nearby the tide gauges. By combining VLM and SLNV with IPCC-AR5 regional projections of climatic data (Representative Concentration Pathways (RCP) 2.6 and 8.5), we provide relative sea-level rise projections by 2100. Results show that the combined effects of SLNV and VLM are not negligible, contributing between 15% and 65% to the sea-level variability. Expected sea levels for 2100 in the RCP8.5 scenario are between 475 ± 203 (Bakar) and 818 ± 250 mm (Venice). In the Venice Lagoon, the mean land subsidence at 3.3 ± 0.85 mm a−1 (locally up to 8.45 ± 1.69 mm a−1) is driving the local sea-level rise acceleration.

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