Can appropriate assessment drive hydraulic risk management towards nature-based solutions? A case study in a Natura 2000 site in central Italy.

Flooding is a natural hazard stemming from heavy rainfall, with a growing global impact due to shifts in land use, particularly urbanization and climate change. Traditional flood damage control methods have predominantly relied on “grey” solutions, involving extensive use of concrete structures, either reinforced or not. The sustainability paradigm has prompted a shift towards solutions inspired by nature, where ecological approaches are integrated with engineering design to enhance risk management. In this context, striking a harmonious balance between the “security objective” and biodiversity preservation, especially in areas governed by the European Council Directive 92/43/EEC, emerges as paramount.
This case study focuses on the hydraulic-integrated environmental restoration of the Rio Santa Croce stream, partially encompassed within a Natura 2000 site (code IT6040024), located in Latina, Italy (Lat. 41.27°N, Long 13.71°E WGS 84). It serves as an illustrative example of how the Natura 2000 network, often perceived merely as a restriction by authorities, technicians and local communities, can be transformed into a valuable tool for steering hydraulic risk management towards nature-based solutions (NBSs). This transformation could be achieved through the appropriate assessment (AA) regulated by Article 3 of the European Council Directive 92/43/EEC.
A multidisciplinary team, comprising professional foresters from the Società Cooperativa Trifolium a.r.l., along with professional engineers and a professional geologist, on behalf of the Province of Latina, conceived a green gabion wall to stabilize the banks of a section of the Rio Santa Croce while creating habitats for aquatic vertebrates. These retaining structures are considered environmental-friendly, offering a more sustainable option compared to traditional earth-retaining walls. By integrating vegetation and implementing special technical measures during the assembly of the baskets, the gabion wall can be classified as NBSs, providing a favorable compromise in situations where the only alternative involves conventional grey solutions.