Po River Deltaic Vulnerability Assessment Using Bayesian Belief Network Approach

Deltaic systems are broadly recognized as vulnerable hotspots at the interface between land and sea, highly exposed to harmful natural and manmade threats. Since the vulnerability to these threats and the biological, physical and anthropogenic processes interactions in low-lying coastal plains such as river deltas are binding for a better understanding in terms of vulnerable systems and to support sustainable management and spatial planning actions in the context of climate change. Here we develop a vulnerability assessment model to design different exposure and vulnerability scenarios considering both ecological and morphological variables derived from Earth Observational (EO) products through the combination of spaceborne optical and SAR imagery in the Po delta and adjoin wetlands (Italy-North Adriatic coast). Institutional user requirements analysis served as guidance for the identification and translation of users' needs relevant to coastal deltaic vulnerability assessment, and preparatory for the model design phase. Bayesian Belief Network approach have been performed to generate different vulnerability scenarios including ecosystem services considering sediments and vegetation patchiness, in order to define relationships between driving forces and coastal responses in the Po delta, that include multi-temporal observations of Sea Level Rise (SLR), local rates of subsidence, significant wave height, exposed LU/LC, and Ocean Color products (TSM, Chl-a, CDOM). The BBN allowed making probabilistic predictions of current and future vulnerability in response to SLR determining the distributions of vulnerability along-shore and underlining expected higher or lower vulnerability portions of the delta. The results helped identify hotspots where vulnerability is expected to increase, thus highlighting the user needs for policy strategies.