GNGTS 2013 - Atti del 32° Convegno Nazionale

depth at which water content decay during the irrigation experiment, quantifying difference in water content zone by zone. 2D Time-lapse ERT in Venice lagoon enhanced how salt marsh plants are able to generate a persisting aerated layer in subsoil, even when flooded. In particular the large hyper-saline plants root uptake seems to be able to determine the persistence of an aerated layer, as previously observed (Marani et al. , 2007, 2006; Ursino et al. , 2004). It is authors’ opinion these analyses may help refine the understanding of the central importance of plant-soil interactions in coupling biological and geomorphological processes (via organic soil production and inorganic sediment trapping). The ERT methodology coupled with the tensiometer data can be used to quantify the dynamics of the soil water content, thus contributing to determine the state and evolutionary trends of tidal landforms forced by anthropogenic pressures and sea level rise. In conclusion the non-invasive Micro-ERT techniques are promising tools for critical soil- plants interaction study, especially if they will support by advanced and accurate hydrological modelling. Suitable modelling techniques will be in fact necessary to exploit the information content of geophysical field data and answer critical questions about basic mechanisms, e.g. the soil moisture balance equations at the scale of the representative elementary volume (Bear, 1971; Richards, 1931). Acknowledgements. We thanks Mario Putti, Giuseppe Fadda, Andrea D’Alpaos and Marco Marani for their invaluable supports for the modeling and interpretation of the results. We thank also Alberto Bellin and Bruno Majone for the Val di Non experiment. Funding for this work is acknowledged from the EU FP7 project CLIMB “Climate Induced Changes on the Hydrology of Mediterranean Basins” and from the Excellence Project “Transport phenomena in hydrological catchments: hydrological and geophysical experiments and modeling” funded by the CARIPARO Foundation. References al Hagrey, S.A. and T. Petersen, 2011, Numerical and experimental mapping of small root zones using optimized surface and borehole resistivity tomography, Geophysics, 76(2) DOI: 10.1190/1.3545067.671 Fig. 3 – Schematic representation of time-lapse resistivity ratio imaging and tensiometer suction as observed during the flood phase in the San Felice marsh (half of the semidiurnal tidal period). The grey area at a depth of 20cm - 40cm (the root zone) represents the ERT resistivity ratio values greater than 100%. The dashed line shows the 40 cm deep tensiometer suction as a function of time, emphasizing drying conditions, (from Boaga et al. , 2013, modified). 95 GNGTS 2013 S essione 3.2