Understanding Crevasse Splay Evolution in Po River Delta (Italy) via Satellite Imagery: Implications for Coastal Resilience

Delta plains are crucial landscapes in many respects. They serve as hotspots for biodiversity, provide fertile land for agricultural practices, and act as natural buffers against coastal storms. However, they face greatly increased risks due to climate change and anthropogenic activities. Previous human interventions based on hard engineering solutions to remediate these coastal systems have largely failed in the long run. Besides being expensive, these measures have disrupted the land-building processes of natural wetlands, compromising the sustainability of these coastal ecosystems and making them more vulnerable to flood risks. This underscores the urgent need for more sustainable, nature-based approaches to realign and restore these vital ecosystems.

River diversion has emerged as an effective strategy for restoring wetlands in river-dominated deltas. This approach involves breaching river levees to restore water flow and sediment deposition in low-lying inundated areas of the deltaic system. The process generates new landforms, such as crevasse splays and crevasse deltas, which provide a foundation for wetland plants to thrive, fostering the development of new wetland ecosystems.

This work focuses on a crevasse delta in the "Isola della Batteria" region, located in the northeastern part of the Po River delta (Italy). The morphological evolution of the area is studied through the analysis of aerial photographs and satellite imagery from Sentinel-2 (2016–2024), Landsat-8 (2013–2016), and Landsat-7 (2009–2013) using QGIS, complemented by sedimentary core and LiDAR data. The study area was previously reclaimed for agricultural purposes but later succumbed to subsidence and became inundated, leading to its abandonment. Between 1999 and 2000, a fluvial flood caused a breach in the levee, initiating the formation of a crevasse delta. By around 2011, the crevasse delta emerged as a subaerial feature and has continued to grow, with vegetation (reeds) progressively colonizing the area and contributing to its development. The newly formed wetland area is approximately 30 hectares. 

The results of this work help to characterize the morphodynamic and depositional elements evolution of a crevasse delta developed in a highly anthropized river delta systems, thereby informing cost-effective strategies for nature-based restoration projects in deltaic wetlands.

This work is part of the research project “Ensuring resilience of the Po River Delta to rising relative sea levels using nature-based solutions for building land and mitigating subsidence (NatResPoNΔ)  ”, a PRIN 2022 PNRR project funded by the European Union – NextGenerationEU.