Impacts of the Po River on Adriatic Sea Hydrodynamics and Interbasin Exchanges

Abstract

One-third of the fresh water in the Adriatic Sea originates from the Po River, influencing the heat, salt budget, and circulation (or hydrodynamics) of the Adriatic. Although many studies highlight the Po River's impact on the Adriatic, uncertainty remains in understanding the potential consequences if the Po River were to dry up due to climate change. Here, we show the dependence of the heat and salt budgets, as well as the hydrodynamics of the Adriatic, on the discharge of the Po River. We use an ocean model of the Adriatic Sea under two scenarios: The control simulation WITHPO reflecting natural conditions during 2018 and incorporating the Po River's freshwater input and an experimental simulation NOPO with the freshwater input turned off. WITHPO generally results in the surface waters in the northern basin being as much as 1.5°C warmer throughout the year, but colder in the spring by 2°C. WITHPO shows a salinity decrease ranging from 0.35 to 1 PSU at the surface. The sea surface height is 5 cm higher in the WITHPO, with the greatest effects observed along the western coast of the Adriatic Sea. The Po River's inflow increases surface outflow and inflow near the seabed between the Adriatic and Ionian Seas. Our results underscore the Adriatic Sea's dependency on Po River discharge and highlight the potential consequences of climate change producing reduced or zero discharge.