Integrating ecological restoration and multi-temporal mobile laser scanning in a natural gas pipeline refurbishment: a case study in Veneto, Italy.

Infrastructure development and environmental conservation are critical challenges in modern engineering. Although pipeline refurbishment projects are essential for maintaining the safety and reliability of energy transportation, can often lead to considerable environmental impacts. With our approach in Pieve di Soligo, Salgareda natural gas pipeline in the Veneto region (Italy) we adopted a sustainable approach to balancing industrial needs with ecological preservation. The pipeline route spans over 37 km across 12 municipalities. The pipeline company implemented a vegetative restoration plan across all the area, focusing on diverse interventions to ensure effective environmental recovery, employing grass planting techniques (hydraulic seeding and manual sowing) as well as reforestation, to reestablish forest or herbaceous cover. For restoration interventions, they planted tree and shrub species matching those present before the project began, placing protective measures such as anti-wild boar wire mesh, to mitigate external stressors. Moreover, they established a five-year cultivation care program, including irrigation, fertilization and pruning to support long-term success. To assess the effectiveness of these interventions, we employed the mobile laser scanner (MLS) FARO Orbis, equipped with SLAM (Simultaneous Localization and Mapping) technology, to capture high-resolution 3D data at four monitoring stations, mapping a total of 2300 m² in approximately 25 minutes with a loop-close path. We conducted the surveys in July and October, obtaining a multi-temporal dataset which allows us for comparative analysis of trees growth over four months. The monitored areas included varied landscapes, from flat agricultural fields dominated by vineyards to moderately sloping wooded regions. We process the data using both FARO Connect and CloudCompare software. We aligned the two point clouds, acquired in different periods from the same area, by using the align command and then we isolated the monitored vegetation using the segment command. By using the CSF Filter plugin, we created the terrain meshes and from them we normalized the point clouds, obtaining the vegetation heights. We analyzed the tree growth patterns by measuring the differences in tree heights in the two survey periods, obtaining an index of the restoration’s effectiveness. Although we achieved vegetation-height assessments, it was not possible to extract variations in diameter at breast height (DBH) because the protective barriers around the trunks obstructed the LiDAR beams. Thanks to the MLS surveys, performed in different time of the year, we can effectively monitor the recovering process and understand if the choices made in the field are giving the expected results. This capability can also facilitate rapid corrective actions, where and if necessary. This study underscores the importance of integrating ecological principles with modern technological methods in infrastructure projects, which allow to extract measurements or observations that are difficult to obtain using traditional surveying techniques. Results from the analysis demonstrate effective recovery of vegetation, offering valuable insights into the long-term sustainability of restoration interventions.