New insights into biodegradable geotextile applications for slope erosion control and greening: final results from two case studies in Canton Ticino, Southern Switzerland

This research project involved the application and monitoring of a bio-based, biodegradable geotextile designed to support revegetation and erosion control on slopes exposed to a combination of unfavorable conditions, while avoiding long-term environmental impacts such as microplastic residues. The two field case studies were located in Maroggia and Chiasso, differing in slope exposure, steepness, and microclimatic conditions. Following the installation of the geotextile in spring 2022, a comprehensive two-year seasonal monitoring program was launched. The monitoring combined terrestrial laser scanning (TLS), UAV multispectral surveys, continuous logging of ground surface temperature and humidity, and field/laboratory soil analyses to evaluate biodegradable erosion-control mats under real environmental conditions. This integrated approach enabled the detection and quantification of changes in slope geometry, vegetation cover, and microclimatic parameters. Vegetation development and overall site performance were influenced by seasonal dynamics, site-specific geomorphological factors, and climatic variability. TLS surveys detected localized material accumulation (soil, leaves, or vegetation mass), but no significant erosion features. UAV multispectral imaging achieved centimetric ground resolution (2.3–2.99 cm/pixel), while NDVI orthomosaics captured seasonal trends and overall greening. Dataloggers recorded ground surface temperature and humidity values consistent with the MeteoSwiss station in Stabio, confirming that the geotextile reduced thermal extremes and preserved soil moisture. Soil analyses revealed only minor differences between sites, with both exhibiting similar mechanical properties (friction angle 35–36°, zero cohesion). These parameters, combined with NDVI indices, were used to identify critical areas for monitoring. By the end of the project, both sites had achieved good vegetation cover and showed no significant erosion, indicating stable slope conditions. At Maroggia, greening was mainly influenced by slope geometry and microclimatic factors, whereas at Chiasso, seasonal climatic variability played the dominant role. Overall, the biodegradable geotextile proved effective in promoting vegetation growth, stabilizing temperature and humidity, maintaining higher soil moisture, and, under certain conditions, mitigating temperature extremes. The results demonstrate that the studied mats represent an effective nature-based solution for vegetation establishment, microclimatic stress reduction, and long-term slope stability.