The proposed injection of seawater in a brackish, sandy aquifer lying 600-800m under the lagoon of Venice to lift Venice itself uniformly up to 30cm in 10years raises many problems. We discuss here whether a smooth uplift can be obtained as claimed by the proponents. We first underline the similarities between the Ravenna and Venice case. We then examine the subsidence around Ravenna because of fluid extraction and the measured surface displacements for the period when there is pressure recovery both in the depleted gas reservoir close to Ravenna and in the upper aquifer system. Uniform surface settlements are nowhere observed and strong influence of local heterogeneities cannot be ruled out. The whole picture suggests great caution and the need for much more investigation before undertaking such an injection.
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