The Po Delta is restarting progradation: geomorphological evolution based on a 47-years Earth Observation dataset

Area of Science:

• Geomorphology
• Environmental Science
• Coastal Dynamics

Background:

• The Po delta, a large anthropogenic delta, has faced significant degradation and shoreline retreat since the 1950s.
• Reduced sediment supply, influenced by human activities and subsidence, has been the primary driver of erosion.
• Past decades showed alternating erosion and stability phases, with substantial stability between 1970 and 2000.

Purpose of the Study:

• To investigate recent changes in the Po delta's geomorphological evolution.
• To determine if the delta is currently experiencing progradation or continued erosion.
• To understand the factors contributing to the delta's recent behavior.

Main Methods:

• Satellite image interpretation to track shoreline changes and delta morphology.
• Analysis of river flow discharge data to assess sediment supply.
• Evaluation of the annual frequency of marine storms impacting the coast.

Main Results:

• The Po delta has resumed delta progradation since 2010, notably in its northern section.
• Active constructive processes are evident, with aggradation of new mouth-bars at the main distributary.
• This recent progradation contrasts with the long-term trend of degradation observed in many deltas globally.

Conclusions:

• The Po delta is currently in a phase of active growth, reversing decades of erosion.
• Increased sediment supply or altered hydrodynamic conditions are likely driving this recent progradation.
• The Po delta's current constructive trend offers a counterexample to global deltaic degradation patterns.