Quantifying the protective capacity of Nature-based Solutions: A Scalable Framework based on multi-decadal data at the Gschliefgraben landslide (Austria)

For decades, alpine hazard management has relied on “grey” infrastructure such as protective structures and retaining walls to provide immediate safety. However, these major construction interventions and investments require regular maintenance, renovation or even replacement. This often involves significant financial efforts and management obligations, entailing open discussions on alternative management approaches.

Nature-based Solutions (NbS) have emerged as a sustainable alternative or complementation to conventional grey interventions within natural hazard management. The various forms of NbS have been serving as a toolkit to complement the hitherto, mainly structure-based protection approach, and they hold potential for a more comprehensive application instead of replacing outdated structures. NBS provide protection over long periods of time, with the biological component being strengthened during maturation and eventually taking over and entirely maintaining the protective function. The greatest advantage is that NbS may provide protection against certain natural hazards types for decades without significant maintenance costs.

Evaluating NbS structures, their effects and performances is currently under scientific focus, however methods for NbS evaluation in a quantifiable manner especially on a large scale, has remained a challenge. In many cases, the benefit of the NbS is evident, but measurability is often lacking. This study evaluates NbS implemented during the last two decades to stabilise the Gschliefgraben landslide area in Upper Austria, as part of the Horizon NatureDEMO project. We combine high-resolution UAV data with on-site inspections to assess the functionality and physical condition of the NbS interventions. These two approaches, when combined, should offer a way to monitor NBS projects on a larger scale more easily.

Furthermore, the study introduces a guideline to quantify the impact and benefits of NbS on basis of figures and parameters. In addition, emphasis is placed on dynamic protection performance to better reflect the time course and biological components of NbS methods. The methodology is linked to measurable variables and is developed in line with Eurocode 2. The ongoing pilot study aims to provide empirical data to build a theoretical framework towards integrating NbS into the Eurocode System.