Land subsidence in Venice and Porto Corsini

L Pieri L Pieri,F Rossi Tesi F Rossi Tesi,M Caputo M Caputo

doi:10.4401/ag-5102

Abstract

This paper is a contribution to t h e study of the problem of subsidence in the Po delta and in t h e Venetian lagoon. We have compared t h e d a t a supplied by tide gauges in Trieste, Venice and Porto Corsini (Fig. 1) during t h e period 1896-1966, and in Genoa in t h e period 1894-1966. Although d a t a were recorded in slightly different periods, these periods are sufficiently overlapping to allow for a significant statistical comparison. We note t h a t the movement of t h e annual mean sea level in Genoa and Trieste is greatly different f r om t h a t of Porto Corsini and Venice and, in order to separate the component due to eustatic effect f r om any possible movement of the coast, we calculate t h e polynomial coefficients, t h a t best fit t h e real movements. Approximating polinomials are of first degree for Genoa and Trieste and of second degree for Porto Corsini and Venice. We have evaluate the coefficients of crosscorrelation firstly on original d a t a and then subtracting f r om original d a ta the best fit polinomials. The correlation is very significant and the trend is similar in Trieste and Genoa. The power spectrum analysis with the direct Fourier's method show long periods wich are shared by tide gauges. We conclude estimating 1,35 mm/year the increase of the mean sea level for t he eustatic effect in the Mediterranean 3,9 mm/year the subsidence in Porto Corsini and 1,4 mm/year the subsidence in Venice.

Highlights

SUMMARY. — Thispaper is acontributiontothestudy of theproblem of subsidence in thePodeltaand in theVenetian lagoon
We note that the movement of theannualmean sea level in GenoaandTrieste is greatlydifferentfromthat of Porto Corsini a n d Venice a n d, in ordertoseparatethecomponentduetoeustatic effect fromany possible movement of t h e coast, we calculate the polynomial coefficients, that best fit the real movements
The tide gauges of Genoa and Trieste are located on solid rocks those of Venice and Porto Corsini are on thick sediments which are known to subside

Summary

Introduction

SUMMARY. — Thispaper is acontributiontothestudy of theproblem of subsidence in thePodeltaand in theVenetian lagoon. Wehavecomparedthedata supplied bytidegauges in Trieste, Venice andPorto Corsini (Fig. 1) during the period 1896-1966, and in Genoa in the period 1894-1966. We note that the movement of theannualmean sea level in GenoaandTrieste is greatlydifferentfromthat of Porto Corsini a n d Venice a n d , in ordertoseparatethecomponentduetoeustatic effect fromany possible movement of t h e coast, we calculate the polynomial coefficients, that best fit the real movements.

Results

Conclusion