La tecnología DGPS en la construcción: control de movimientos en grandes estructuras

The joint development of auscultation and communications technologies is enabling the development of Automated Monitoring Systems for structures. In this paper, we analyze the viability of the application of DGPS (Differential GPS) technique to monitoring in construction. We can affirm DGPS is accurate and useful for the auscultation of large structures, such as dams, reflecting properly their movements and deformations, compared to geotechnical sensors. The use of DGPS technology in large structures can provide information on the dynamic characteristics of their movements and deformations. All this can be analyzed in real time, with automated measurement systems and alarms programmed for different thresholds. Therefore DGPS is considered a complementary technique for auscultation of large structures that can integrate with other geotechnical or topographical methods, both in the construction and monitoring phases.La evolución conjunta de las tecnologías de auscultación y las telecomunicaciones está permitiendo el desarrollo de Sistemas de Auscultación Automática de estructuras. En este trabajo se analiza la viabilidad de la aplicación de la técnica DGPS a la auscultación en construcción. Se puede afirmar que el GPS diferencial es preciso y útil en la auscultación de grandes estructuras, como las presas, al reflejar adecuadamente el movimiento de las mismas, en comparación con los sensores geotécnicos. El empleo de DGPS en grandes estructuras puede proporcionar información sobre sus movimientos y deformaciones. Esta información puede estar disponible en tiempo real, con sistemas automáticos de medición y alarmas programadas para distintos umbrales de movimientos. Por todo ello, se considera que el DGPS es una tecnología complementaria para la auscultación de grandes estructuras, que puede integrarse con otros métodos geotécnicos o topográficos, tanto en la fase constructiva como en el seguimiento de las obras

Aplicación del Láser Escáner Terrestre (TLS) a la modelización de estructuras: precisión, exactitud y diseño de la adquisición de datos en casos reales

Terrestrial laser scanner is employed in a wide range of engineering applications, because of the specifications of TLS units and the good precision reached. This paper presents the application of TLS to structures and walls modeling. It analyzes the factors that influence final accuracy: cloud registration, target type and the effect of scanning angle and distance. A field test was performed with calibrated panels, obtaining real precision and accuracy values for the most common distance ranges in engineering. We propose and validate the usage of pattern graphs relating precision and accuracy versus distance and scanning angle for field survey design. The application of pattern graph in the design of field scan surveys for dam movement control is also presented. Recommendations are made for the application of TLS technique to large structures.El láser escáner terrestre se emplea en numerosas aplicaciones de Ingeniería, debido a las prestaciones de los equipos y a las precisiones alcanzadas. Se presenta la aplicación del TLS a la modelización de estructuras y paramentos verticales. Se analizan los factores que influyen en la precisión final: registro de nubes, tipo de dianas y el efecto del ángulo y distancia de escaneo. Se realizó una prueba de campo con testigos calibrados, obteniendo valores reales de precisión y exactitud para los rangos de distancia más usuales en Ingeniería. Se propone y valida el empleo de gráficos patrón que relacionan las variables precisión y exactitud con los factores distancia y ángulo de escaneo para el diseño de trabajos de campo. Se expone su aplicación al diseño de los escaneos para el control de movimientos de una presa. Se realizan recomendaciones para la aplicación de la técnica TLS a grandes estructuras

Aplicación del Láser Escáner Terrestre (TLS) a la modelización de estructuras: precisión, exactitud y diseño de la adquisición de datos en casos reales

Terrestrial laser scanner is employed in a wide range of engineering applications, because of the specifications of TLS units and the good precision reached. This paper presents the application of TLS to structures and walls modeling. It analyzes the factors that influence final accuracy: cloud registration, target type and the effect of scanning angle and distance. A field test was performed with calibrated panels, obtaining real precision and accuracy values for the most common distance ranges in engineering. We propose and validate the usage of pattern graphs relating precision and accuracy versus distance and scanning angle for field survey design. The application of pattern graph in the design of field scan surveys for dam movement control is also presented. Recommendations are made for the application of TLS technique to large structures.<br><br>El láser escáner terrestre se emplea en numerosas aplicaciones de Ingeniería, debido a las prestaciones de los equipos y a las precisiones alcanzadas. Se presenta la aplicación del TLS a la modelización de estructuras y paramentos verticales. Se analizan los factores que influyen en la precisión final: registro de nubes, tipo de dianas y el efecto del ángulo y distancia de escaneo. Se realizó una prueba de campo con testigos calibrados, obteniendo valores reales de precisión y exactitud para los rangos de distancia más usuales en Ingeniería. Se propone y valida el empleo de gráficos patrón que relacionan las variables precisión y exactitud con los factores distancia y ángulo de escaneo para el diseño de trabajos de campo. Se expone su aplicación al diseño de los escaneos para el control de movimientos de una presa. Se realizan recomendaciones para la aplicación de la técnica TLS a grandes estructuras

Mechanisms of Degradation and Identification of Connectivity and Erosion Hotspots

The context of processes and characteristics of soil erosion and land degradation in Mediterranean lands is outlined. The concept of connectivity is explained. The remainder of the chapter demonstrates development of methods of mapping, analysis and modelling of connectivity to produce a spatial framework for development of strategies of use of vegetation to reduce soil erosion and land degradation. The approach is applied in a range of typical land use types and at a hierarchy of scale from land unit to catchment. Patterns of connectivity and factors influencing the location and intensity of processes are identified, including the influence of topography, structures such as agricultural terraces and check dams, and past land uses. Functioning of connectivity pathways in various rainstorms is assessed. Modes of terrace construction and extent of maintenance, as well as presence of tracks and steep gradients are found to be of importance. A method of connectivity modelling that incorporates effects of structure and vegetation was developed and has been widely applied subsequently

Deformation monitoring of dam infrastructures via spaceborne MT-InSAR. The case of La Viñuela (Málaga, southern Spain)

Dams require continuous security and monitoring programs, integrated with visual inspection and testing in dam surveillance programs. New approaches for dam monitoring focus on multi-sensor integration, taking into account emerging technologies such as GNSS, optic fiber, TLS, InSAR techniques, GBInSAR, GPR, that can be used as complementary data in dam monitoring, eliciting causes of dam deformation that cannot be assessed with traditional techniques. This paper presents a Multi-temporal InSAR (MT-InSAR) monitoring of La Viñuela dam (Málaga, Spain), a 96 m height earth-fill dam built from 1982 to 1989. The presented MT-InSAR monitoring system comprises three C-band radar (~5,7 cm wavelength) datasets from the European satellites ERS-1/2 (1992-2000), Envisat (2003-2008), and Sentinel-1A/B (2014-2018). ERS-1/2 and Envisat datasets were processed using StaMPS. In the case of Sentinel-1A/B, two different algorithms were applied, SARPROZ and ISCE-SALSIT, allowing the comparison of the estimated LOS velocity pattern. The obtained results confirm that LaViñuela dam is deforming since its construction, as an earth-fill dam. Maximum deformation rates were measured in the initial period (1992-2000), being around -7 mm/yr (LOS direction) on the coronation of the dam. In the period covered by the Envisat dataset (2003-2008), the average deforming pattern was lower, of the order of -4 mm/yr. Sentinel-1A/B monitoring confirms that the deformation is still active in the period 2014-2018 in the central-upper part of the dam, with maximums of velocity reaching -6 mm/yr. SARPROZ and ISCE-SALSIT algorithms provide similar results. It was concluded that MT-InSAR techniques can support the development of new and more effective means of monitoring and analyzing the health of dams complementing actual dam surveillance systems

MT-InSAR and Dam Modeling for the Comprehensive Monitoring of an Earth-Fill Dam: The Case of the Benínar Dam (Almería, Spain)

The Benínar Dam, located in Southeastern Spain, is an earth-fill dam that has experienced filtration issues since its construction in 1985. Despite the installation of various monitoring systems, the data collected are sparse and inadequate for the dam’s lifetime. The present research integrates Multi-Temporal Interferometric Synthetic Aperture Radar (MT-InSAR) and dam modeling to validate the monitoring of this dam, opening the way to enhanced integrated monitoring systems. MT-InSAR was proved to be a reliable and continuous monitoring system for dam deformation, surpassing previously installed systems in terms of precision. MT-InSAR allowed the almost-continuous monitoring of this dam since 1992, combining ERS, Envisat, and Sentinel-1A/B data. Line-of-sight (LOS) velocities of settlement in the crest of the dam evolved from maximums of −6 mm/year (1992–2000), −4 mm/year (2002–2010), and −2 mm/year (2015–2021) with median values of −2.6 and −3.0 mm/year in the first periods (ERS and Envisat) and −1.3 mm/year in the Sentinel 1-A/B period. These results are consistent with the maximum admissible modeled deformation from construction, confirming that settlement was more intense in the dam’s early stages and decreased over time. MT-InSAR was also used to integrate the monitoring of the dam basin, including critical slopes, quarries, and infrastructures, such as roads, tracks, and spillways. This study allows us to conclude that MT-InSAR and dam modeling are important elements for the integrated monitoring systems of embankment dams. This conclusion supports the complete integration of MT-InSAR and 3D modeling into the monitoring systems of embankment dams, as they are a key complement to traditional geotechnical monitoring and can overcome the main limitations of topographical monitoring

Flow regime patterns and their controlling factors in the Ebro basin (Spain)

Natural intra-annual flow fluctuations vary between rivers, being a determining factor for aquatic insects, fish and riparian communities which are adapted to the habitat conditions and different flows throughout the seasons. Moreover, restoration of seasonal flow patterns plays an important role in achieving good ecological status of rivers, through the preservation and/or recovery of components and processes of natural river ecosystems. In this work we: (a) classify fluvial segments in the Ebro basin (North-Eastern Spain) according to the intra-annual variability of flows under natural conditions using statistical cluster analysis of monthly mean flow data; (b) characterise the resulting flow typologies according to several ecologically important hydrological variables; (c) analyse the relationships between flow regimes of fluvial segments and physical variables from their catchments; and finally (d) predict the most probable natural flow regime using logistic models based on the most determinant physical characteristics. Fifteen natural flow typologies were described in the Ebro basin, which were characterised in terms of flow fluctuation through the year as well as timing, flow ratio and duration of the maximum and minimum flows. Precipitation, biogeography and geology of catchments showed the highest correlations with flow regimes. Basin size, mean elevation and slope were also correlated. The logistic model we developed had a prediction success of 72% in the Ebro basin. The definition of the natural hydrological conditions (to which the biological communities are tailored), even when flow data are not available, is an important support in the management of river ecosystems. It is especially suitable for setting goals in aquatic ecosystem conservation or restoration projects

Developmental Exposure to a Toxic Spill Compromises Long-Term Reproductive Performance in a Wild, Long-Lived Bird: The White Stork (Ciconia ciconia)

Background/Objective: Exposure to environmental contaminants may result in reduced reproductive success and long- lasting population declines in vertebrates. Emerging data from laboratory studies on model species suggest that certain life- stages, such as development, should be of special concern. However, detailed investigations of long-term consequences of developmental exposure to environmental chemicals on breeding performance are currently lacking in wild populations of long-lived vertebrates. Here, we studied how the developmental exposure to a mine spill (Aznalco´ llar, SW Spain, April 1998) may affect fitness under natural conditions in a long-lived bird, the White Stork (Ciconia ciconia). Methodology: The reproductive performance of individually-banded storks that were or not developmentally exposed to the spill (i.e. hatched before or after the spill) was compared when these individuals were simultaneously breeding during the seven years after the spill occurred (1999–2005). Principal Findings: Female storks developmentally exposed to the spill experienced a premature breeding senescence compared with their non-developmentally exposed counterparts, doing so after departing from an unusually higher productivity in their early reproductive life (non-developmentally exposed females: 0.560.33SE fledglings/year at 3-yr old vs. 1.3860.31SE at 6–7 yr old; developmentally exposed females: 1.560.30SE fledglings/year at 3-yr old vs. 0.8660.25SE at 6– 7 yr old). Conclusions/Significance: Following life-history theory, we propose that costly sub-lethal effects reported in stork nestlings after low-level exposure to the spill-derived contaminants might play an important role in shaping this pattern of reproduction, with a clear potential impact on population dynamics. Overall, our study provides evidence that environmental disasters can have long-term, multigenerational consequences on wildlife, particularly when affecting developing individuals, and warns about the risk of widespread low-level contamination in realistic scenarios.Peer reviewe