Climate Projections of salt-wedge intrusions in a Po river branch
(Northern Adriatic Sea)
Abstract
Estuaries are the transitional systems between the riverine freshwaters
and the ocean salt water. Increasing salt-wedge intrusions are mentioned
as one of the major impacts of climate change in coastal areas. We
propose a new methodology to predict salt wedge intrusions with an
intermediate complexity model, so-called Estuarine Box Model (EBM), that
allows to use hydrology and ocean climate scenarios to predict salt
wedge intrusions. We apply this methodology to the Goro branch of the Po
river flowing into the Northern Adriatic Sea. A 30 years’ period
(1982-2011) is used to train and test the EBM that is then used to
project the salt wedge in the (2021-2050) time period under the RCP8.5
emission scenario. The numerical results show that in the (2021-2050)
period, the Po di Goro salt wedge intrusion length will increase by 15%
on an annual basis (up to 50% in summertime) and the outflowing
salinity will increase 9% on annual basis (up to 35% in summer).
Finally, a statistical estimation of the extreme values of salt wedge
and outflowing salinity shows return periods of 10 years for extremes
twice the present mean values. It means that a 16 Km of salt-wedge
intrusion, and outgoing salinity about 28 psu are highly expected as an
extreme event with 10 years return period