|TITLE||LONG-TERM HYDROLOGICAL VARIABILITY OVER NORTHERN ITALY FROM IONIAN SEA SEDIMENTS|
|AUTHORS||Carla Taricco (1,2), Silvia Maria Alessio (1,2), Sara Rubinetti (1), Davide Zanchettin (3), Simone Cosoli (4), Miroslav Gacic (4), Salvatore Mancuso (2), Angelo Rubino (3)|
- Dipartimento Di Fisica - UniversitÃ Di Torino, Torino (Italy)
- Osservatorio Astrofisico Di Torino (inaf), Torino (Italy)
- UniversitÃ Ca' Foscari, Venezia (Italy)
- Istituto Nazionale Di Oceanografia E Geofisica Sperimentale (ogs), Sgonico, Trieste (Italy)
|ABSTRACT||We use a high-resolution foraminiferal delta18O record from a sediment core in the Ionian Sea to reconstruct for the first time the North Italian hydrological variability on millennial-scale. We focus on the Po River, which inherently integrates information about regional climate hydrological variability since its catchment encompasses a large part of Northern Italy. Using the 200-year-long historical discharge record and oceanographic measurements along the Adriatic Italian coast, we demonstrate that the Po River discharge undergoes robust decadal fluctuations that reach the Ionian Sea, ~1000 km South of Po River delta, through propagating salinity anomalies.
We show that these anomalies are recorded in Ionian Sea sediments as foraminiferal delta18O decadal-scale variations that we measured over the last 2000 years. This allows for reconstructing the Po river discharge back into the past and showing that the highly significant decadal variability persists over the last two millennia.
Archival reports on floods in the Po basin during the last two millennia corroborate the hydrological variations depicted by our reconstruction. The maximum reconstructed amplitudes occur around the 16th and 17th centuries and correspond to an exceptional series of documented floods which struck Northern Italy. On the other hand, periods of weak reconstructed amplitude coincide with periods when no flooding events were reported.
Our study provides the first millennial-scale reconstruction of the strength of decadal hydrological variability over Northern Italy.|