Coupled thermohydromechanical analysis of Venice lagoon salt marshes

Cola, Simonetta; Sanavia, Lorenzo; Simonini, Paolo; Schrefler, Bernhard A.

doi:10.1029/2007wr006570

Cited by 24 publications

(26 citation statements)

References 39 publications

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“…Regarding (iii), since the presence of cracks is crucial in promoting bank retreat, their formation deserves more attention. Some authors proposed different mechanisms for their occurrence in marsh environment: desiccation processes across seasonal variation [ Allen , ; Morris et al ., ] and cyclic oscillation of mean and effective stresses due to tide [ Cola et al ., ]. Both mechanisms act at large time scale, and they involve filtration processes.…”

Section: Discussionmentioning

confidence: 99%

“…Tension cracks most frequently form at the end of the summer season due to the drying and shrinkage of the soil [ Allen , ; Morris et al ., ]; furthermore, Cola et al . [] hypothesized that the formation of tension cracks induced by the cyclic oscillation of mean and effective stresses is due to tidal wave fluctuation. Recent experimental results [ Francalanci et al ., ] have shown that toppling failure typology can occur during salt marsh retreat processes, especially under the effect of wind wave forcing, and can be triggered by the presence of tension cracks.…”

Section: Introductionmentioning

confidence: 99%

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On salt marshes retreat: Experiments and modeling toppling failures induced by wind waves

Bendoni

Francalanci²,

Cappietti

et al. 2014

J. Geophys. Res. Earth Surf.

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Salt marshes are delicate ecosystems which are disappearing in many areas of the world, mainly due to increasing rates of sea level rise, subsidence, and anthropic pressure. The lateral erosion of the edge of salt marshes is one of the most important processes in determining changes in morphology, and wind waves have a key role in this retreat. Lateral retreat occurs by means of several types of mass failure processes, typically cantilever, sliding, and toppling. In the literature, no mechanistic models for the description of toppling failure are available. In this study, we performed a set of experiments to quantify the pressure field and the hydrodynamic forcing induced by wind waves during toppling failures of unstable blocks on a salt marsh edge. We propose a model interpreting toppling failure based on the experimental evidence as well as on the physics of the system. We model the system as a dynamic rigid block of cohesive soil, identified by the presence of a tension crack, subjected to hydrodynamic forces caused by impact of waves and resistive forces due to the block's weight and soil cohesion. The failure of the blocks occurs when the soil tensile strength is exceeded along the failure surface located at the base of the block. The model is able to reproduce failure processes observed in the laboratory. Moreover, the model reveals that the most critical conditions for marsh bank instability due to toppling failure are associated to the presence of water inside the tension crack and low water levels in front of the bank.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

On salt marshes retreat: Experiments and modeling toppling failures induced by wind waves

Bendoni

Francalanci²,

Cappietti

et al. 2014

J. Geophys. Res. Earth Surf.

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“…Reported saturated hydraulic conductivity values similar to our 0.07-0.0007 m d À1 values include an Australian estuarine marsh, 0.01-0.17 m d À1 [Hughes et al, 1998], and a Venice lagoon marsh, 0.00017 m d À1 (core) and 0.086-0.00086 m d À1 (models) [Cola et al, 2008]. Regarding topography, the use of a kriged surface in the central portion of our models did not capture microtopographic variations in surface elevation that might affect very local hydraulics.…”

Section: Limitations Of the Modelsmentioning

confidence: 91%

Salt marsh ecohydrological zonation due to heterogeneous vegetation–groundwater–surface water interactions

Moffett¹,

Gorelick²,

McLaren³

et al. 2012

Water Resources Research

112

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[1] Vegetation zonation and tidal hydrology are basic attributes of intertidal salt marshes, but specific links among vegetation zonation, plant water use, and spatiotemporally dynamic hydrology have eluded thorough characterization. We developed a quantitative model of an intensively studied salt marsh field site, integrating coupled 2-D surface water and 3-D groundwater flow and zonal plant water use. Comparison of model scenarios with and without heterogeneity in (1) evapotranspiration rates and rooting depths, according to mapped vegetation zonation, and (2) sediment hydraulic properties from inferred geological heterogeneity revealed the coupled importance of both sources of ecohydrological variability at the site. Complex spatial variations in root zone pressure heads, saturations, and vertical groundwater velocities emerged in the model but only when both sources of ecohydrological variability were represented together and with tidal dynamics. These regions of distinctive root zone hydraulic conditions, caused by the intersection of vegetation and sediment spatial patterns, were termed ''ecohydrological zones'' (EHZ). Five EHZ emerged from different combinations of sediment hydraulic properties and evapotranspiration rates, and two EHZ emerged from local topography. Simulated pressure heads and groundwater dynamics among the EHZ were validated with field data. The model and data showed that hydraulic differences between EHZ were masked shortly after a flooding tide but again became prominent during prolonged marsh exposure. We suggest that ecohydrological zones, which reflect the combined influences of topographic, sediment, and vegetation heterogeneity and do not emphasize one influence over the others, are the fundamental spatial habitat units comprising the salt marsh ecosystem.

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“…[] for a detailed description of the study site). Shallower soils in the Venice Lagoon are characterized by sandy clay and silt successions [ Cola et al ., ]. The ERT application to the San Felice marsh is based on custom‐made waterproof micro‐ERT boreholes, acting in two microboreholes plus surface electrodes.…”

Section: Methodsmentioning

confidence: 99%

Plant‐soil interactions in salt marsh environments: Experimental evidence from electrical resistivity tomography in the Venice Lagoon

Boaga

D’Alpaos

Cassiani

et al. 2014

Geophysical Research Letters

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The role of root water uptake in regulating soil water saturation in salt marshes is controversial.Modeling studies suggest that soil aeration is improved by transpiration, with implications for the distribution of vegetation species and of the associated topographic features controlling the hydraulic regime of the marshland and eventually its survival. Marsh vegetation plays a key role in the preservation of such critical environment, which represents unique marker for climatic change and impact studies. However, the direct quantification of space-time aeration patterns has remained elusive, in part, because of the limitations posed by high salinity to conventional observation techniques such as time or frequency domain reflectometry. Here we show that time-lapse microscale electrical resistivity tomography, coupled with tensiometric observations, allows the identification of variably saturated zones and the characterization of space-time soil moisture dynamics in a salt marsh in the Venice Lagoon (Italy). This is the first quantitative observational experiment which confirms that periodically flooded plants are capable of producing a persistently aerated layer below the flooded surface when transpiration proceeds at a sufficiently high rate. The experimental results are compared against previously published model predictions.

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Coupled thermohydromechanical analysis of Venice lagoon salt marshes

Cited by 24 publications

References 39 publications

On salt marshes retreat: Experiments and modeling toppling failures induced by wind waves

On salt marshes retreat: Experiments and modeling toppling failures induced by wind waves

Salt marsh ecohydrological zonation due to heterogeneous vegetation–groundwater–surface water interactions

Plant‐soil interactions in salt marsh environments: Experimental evidence from electrical resistivity tomography in the Venice Lagoon

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