Assessment of long-term structural movements in a historic cliffside construction through Lomb-Scargle spectral analysis of unevenly spaced time records: the Punta Begona Galleries (Getxo, Spain)

Long-term monitoring of structural movements in historic buildings and heritage sites allows assessing their stability and recognizing damages that require intervention. The Punta Begona Galleries, built in the earlier part of the twentieth century, present pioneering techniques in the use of reinforced concrete in building construction. They stand directly over a coastal cliff, and their recovery requires first to guarantee their stability, while maintaining their historic and patrimonial values. Thus, with the goal of analyzing their global stability, as well as the extent of the observed damages, we implemented a motion monitoring network that includes three boreholes for extensometric control, an inclinometer, and five crack gauges (crackmeters). This monitoring was complemented with the recording of hydrometeorological variables at the surface and in four piezometers. The spectral analysis of the signals of movements was performed by introducing the use of the Lomb-Scargle (LS) periodogram, which is particularly well-suited for the analysis of unevenly spaced time series. This analysis allowed us to differentiate the reversible seasonal elastic components of the records and to recognize the irreversible long-term plastic displacements, which highlight the sectors with active instability. In our case, the identified damages are related to two local problems of building support. Even though the irreversible component of the displacement after seasonal sinusoidal detrending is small (with maximums up to 0.12 mm/year), it does imply a dynamic plastic deformation, which calls for the need to adopt structural stabilization measures.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature

Rockfall hazard mitigation in coastal environments using dune protection: A nature-based solution case on Barinatxe beach (Basque Coast, northern Spain)

Across the world, coastal environments of great landscape, recreational and environmental value are coming under increasing pressure. Within such environments, cliffs are particularly characteristic and unique elements, in which processes of instability develop. Their management requires a transdisciplinary approach ensuring protection of the natural condition of the environment, while at the same time allowing for their continued use and enjoyment. In the case of Barinatxe (Basque Coast), the beach has evolved into a system of foredunes, flanked by cliffs with frequent rockfall processes. This research analyzes the effect of coastal dunes as an element of natural protection. To this end, based on a Digital Terrain Model developed by Terrestrial Laser Scanning (TLS) and in situ geological characterization, 3D modeling has been used to analyze rockfall trajectories and evaluate their runout and energy. These models confirm the protective role of coastal dunes, which act as efficient natural barriers against rock blocks that become detached from cliffs. This is particularly important in areas where the use of tools based on Nature-Based Solutions (NBSs) guidelines is recommended.This study has been carried out by the UPV/EHU Research Group IT1678-22 (Government of the Basque Country) in the framework of the strategic project “Analysis of instabilities in coastal environments of the Basque Country” PES-18/97 (University of the Basque Country)

Landforms of the lower Hushe Valley (Central Karakoram, Pakistan)

This paper presents a new geomorphological map for the lower Hushe Valley (below 3400 m asl), located to the SE of the Central Karakoram in Baltistan (North Pakistan). Fieldwork and remote sensing were combined to improve understanding of the most recent surface landforms to produce a 1:50,000 scale map. Thirteen landform types associated with glacial, fluvial, gravitational and mass wasting processes were identified and mapped. Particular emphasis was made on currently dynamic processes that could pose a threat to the population. The distribution of the landforms on the valley (reworked tills, alluvial fans, rockfalls, among others) differs between the eastern and the western hillslopes, and from north to south, mainly due to bedrock types, location of geological structures and distribution of lateral tributaries. This map is the first and necessary step towards a deep assessment on geological risk related to external processes in the area.This research was funded by the Basque Government (Eusko Jaurlaritza) through the Humanitarian Action 2018 fund (PRE2018EH/0004) and the Consolidated Research Group IT1029-16. We also thank the University of the Basque Country UPV/EHU for the suppor

Rockfall susceptibility analysis through 3D simulations in marine protected areas of the Portofino coastline: case studies of San Fruttuoso and Paraggi bays

The research focuses on the assessment of the potential geomorphological hazards affecting the stability of the Promontory of Portofino (Regional Natural Park of Portofino, Northern Italy), mainly on the bays of San Fruttuoso and Paraggi. The study area constitutes one of the most representative and most populated environments, both by locals and tourists, of the entire Liguria area. For this reason, there is a growing need for investigation on the natural dynamics of these landscapes, based on detailed topographic information. The research starts from a regional geological and geomorphological analysis specific to the study area, combined with a multi-model comparison algorithm (M3C2), which allows comparing two LiDAR datasets acquired in 2008 and 2020, respectively, to assess the overall dynamics of the promontory development. Then, a detailed study of San Fruttuoso and Paraggi bays, two key points for visitors and therefore for management, is performed. Three-dimensional modeling of rockfalls is carried out, which allows the development of a specific management oriented to the use of nature-based solutions (NBSs) strategies, respecting the environment and increasing safety against instability processes in these areas.This study has been carried out in the framework of a collaboration among ISPRA, GISIG, Universita di Genova, and Universidad del Pais Vasco (UPV/EHU, IT1678-22 Research Group, PES-18/92 Project) within the RECONECT Project (Regenerating ECOsystems with Nature-based solutions for hydro-meteorological risk rEduCTion)