Modelling wave-driven sediment transport in a changing climate: a case study for northern Adriatic Sea (Italy)

In this paper, we investigate the impact of climate change on coastal sediment transport in a deltaic system in the northern Adriatic Sea, with reference to the period 2070-2099 in the IPCC A1B emission scenario. Wind fields obtained by means of the high-resolution regional climate model Consortium for Small-scale Modelling-Climate Limited-area Modelling were employed for computing wave climate at basin scale by means of the spectral wave model Simulating Waves Nearshore. This was used as a constraint for a nearshore hydromorphodynamic model (MIKE LITPACK), which was applied to a test site on the Po River Delta, located in northern Italy. Relevant sediment transport processes have been studied at storm and decadal time scales in order to capture climate change effects on single events and as an overall trend. The transport rates in the A1B climate change scenario were then compared with the corresponding results of a control analysis (period 1965-1994) representing the actual climate. Although predicted wave climate in the investigated scenario displays an overall decrease in sea severity offshore in the northern Adriatic Sea, the effects of these modifications are modulated during the onshore propagation, with different impacts on sediment transport depending on the considered process and time scale. The strategy presented in this work can find fruitful applications in the long-term modelling of coastal and transitional environments, in which morphology is strongly influenced by sediment transport in the nearshore zone, suggesting a methodological approach for coastal planning and management.