EGU24-17855, updated on 11 Mar 2024
https://doi.org/10.5194/egusphere-egu24-17855
EGU General Assembly 2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Storm-surge barriers induce loss of geomorphic diversity in shallow tidal embayments

Luca Carniello1, Davide Tognin1, Alvise Finotello2, Daniele Pietro Viero1, Mattia Pivato1, Riccardo Alvise Mel3, Andrea Defina1, Enrico Bertuzzo4, Marco Marani1, and Andrea D'Alpaos2
Luca Carniello et al.
  • 1University of Padova, Department of Civil, Environmental, and Architectural Engineering,
  • 2University of Padova, Department of Geosciences
  • 3Italian Institute for Environmental Protection and Research
  • 4Ca’ Foscari University of Venice, Department of Environmental Sciences, Informatics and Statistics

Flood regulation systems and storm-surge barriers are increasingly being employed to safeguard coastal cities worldwide from the threats of flooding linked to rising sea levels. Prominent examples include London, the Netherlands, New Orleans, St. Petersburg, and Venice. While these barriers effectively control the propagation of surges and tides, they also induce changes in sediment transport, consequently altering the morphological evolution of estuarine systems near the protected urban areas. However, the precise impact of flood regulation on the morphodynamic evolution of tidal environments remains an unanswered question.

Our study delves into the effects of recently activated storm-surge barriers, designed to protect Venice (Italy) from flooding, on the morphological evolution of the Venice Lagoon. This investigation combines numerical modeling with field data.

The artificial reduction of water levels influences the interaction between tides and waves, leading to increased sediment resuspension on tidal flats. However, the deposition of resuspended sediments on salt marshes is importantly reduced by the diminished flooding intensity and duration resulting from artificially-lowered water levels. This situation could potentially compromise the marsh's ability to adapt to rising sea levels via mineral sediment deposition. At the same time, eroded sediments tend to accumulate within channels, thereby impeding water exchange and escalating dredging costs.

Over longer (i.e., seasonal) timescales, we propose that while barrier closures decrease net sediment export to the open sea, they do not necessarily preserve the characteristic lagoonal morphology. Instead, this may hinder salt marsh vertical accretion, promote tidal flat deepening, and lead to channel infilling. Consequently, the operation of flood barriers could trigger a significant loss of tidal landforms, adversely impacting the preservation of shallow tidal environments and the valuable ecosystem services they provide.

How to cite: Carniello, L., Tognin, D., Finotello, A., Viero, D. P., Pivato, M., Mel, R. A., Defina, A., Bertuzzo, E., Marani, M., and D'Alpaos, A.: Storm-surge barriers induce loss of geomorphic diversity in shallow tidal embayments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17855, https://doi.org/10.5194/egusphere-egu24-17855, 2024.