Compound river and coastal flooding/drought events in the Po delta area

The interconnected nature of catchment hydrology and marine circulation processes poses significant challenges to the numerical modelling of river and coastal flood/drought conditions in the catchment-sea continuum.

Finite Element Modelling (FEM) provides an advanced solution, offering the ability to handle cross-scale and multi-scale processes with adaptive unstructured meshes, which are crucial for accurately representing complex coastlines and varying bathymetry. This makes FEM well-suited for seamless modelling of inland and marine water systems.

Compound flooding and drought events are becoming increasingly frequent and intense across many catchment areas draining into the Mediterranean basin. To address these challenges, we used a seamless numerical modelling of the river-sea continuum based on a Finite Element code (SHYFEM-MPI-ZSTAR, Micaletto et al 2022, Verri et al 2023). By progressively refining the SHYFEM-MPI-ZSTAR experimental settings, we aim to deepen our understanding of compound flooding and drought events occurring in the Po River delta system, which is Italy's longest river and the second-largest freshwater source for the Mediterranean basin.

A four-year experiment (2019 to 2023) was conducted to simulate significant events, including the November 2019 flood and the July 2022 drought. Model findings were validated against available in-situ and satellite observations.

We explored the role of non-linear combination of multi-scale and cross-scale forcing mechanisms to enhance the modeling accuracy and the understanding of the complex physical processes underlying such extreme events.