Multi-component and multi-source approach to model subsidence in deltas. Application to Po Delta Area

This thesis focused on the definition of a study approach able to deal with the complexity of the land subsidence phenomenon in deltas. In the framework of the most up- to-date multi-methodological and multi-disciplinary studies concerning land subsidence and targeting to predict and prevent flooding risk, the thesis introduces a procedure based on two main innovations: the multi-component study and the multi-source analysis. The proposed approach is a “multi-component” procedure as it investigates, in the available geodetic datasets, the permanent component apart from the periodic one, and, at the same time, it is a “multi-source” approach because it attempts to identify the relevant processes causing subsidence (sources) by a modelling based on multi-source data analysis. The latter task is accomplished first through multi-disciplinary and multi-methodological comparative analyses, then through modelling of the selected processes. With respect to past and current approaches for studying subsidence phenomena, the developed procedure allows one to: i. overcome the one-component investigation, improving the accuracy in the geodetic velocity estimate; ii. fix the “analyses to modelling” procedure, enhancing qualitative or semi-quantitative procedures that often characterize the “data to source” and the “residual to source” approaches; iii. quicken the source validation phase, accrediting the relevance of the source on the basis of the analysis results and before the modelling phase, differently from the “peering approach”, which validates the source on the basis of the model findings. The proposed procedure has been tested on the Po Delta (northern Italy), an area historically affected by land subsidence and recently interested by accurate continuous geodetic monitoring through GNSS stations. Daily-CGPS time series (three stations), weekly- CGPS time series (two stations) and seven sites of DInSAR-derived time series spanning over the time interval 2009 – 2017 constituted the used geodetic datasets. Several meteo/hydro parameters collected from fifty-seven stations and wide stratigraphic-geological information formed the base for the performed comparative analyses. From the application of the proposed procedure, it turns out that the periodic annual component highlighted in the continuous GPS stations is explained by two water mass-dependent processes: soil moisture mass change, which seems to control the ground level up-or-down lift in the southern part of the Delta, and the river water mass change, which influences the ground displacement in the central part of the Delta. As it concerns the permanent component, the lower rate found over 2012 - 2016 period in the central part of the Delta with respect to the eastern part is interpreted as due to the sediment compaction process of the Holocene prograding sequences and to the increase of rich-clay deposits

Beyond the angle of repose: A review and synthesis of landslide processes in response to rapid uplift, Eel River, Northern California

In mountainous settings, increases in rock uplift are often followed by a commensurate uptick in denudation as rivers incise and steepen hillslopes, making them increasingly prone to landsliding as slope angles approach a limiting value. For decades, the threshold slope model has been invoked to account for landslide-driven increases in sediment flux that limit topographic relief, but the manner by which slope failures organize themselves spatially and temporally in order for erosion to keep pace with rock uplift has not been well documented. Here, we review past work and present new findings from remote sensing, cosmogenic radionuclides, suspended sediment records, and airborne lidar data, to decipher patterns of landslide activity and geomorphic processes related to rapid uplift along the northward-migrating Mendocino Triple Junction in Northern California. From historical air photos and airborne lidar, we estimated the velocity and sediment flux associated with active, slow-moving landslides (or earthflows) in the mélange- and argillite-dominated Eel River watershed using the downslope displacement of surface markers such as trees and shrubs. Although active landslides that directly convey sediment into the channel network account for only 7% of the landscape surface, their sediment flux amounts to more than 50% of the suspended load recorded at downstream sediment gaging stations. These active slides tend to exhibit seasonal variations in velocity as satellite-based interferometry has demonstrated that rapid acceleration commences within 1 to 2 months of the onset of autumn rainfall events before slower deceleration ensues in the spring and summer months. Curiously, this seasonal velocity pattern does not appear to vary with landslide size, suggesting that complex hydrologic–mechanical feedbacks (rather than 1-D pore pressure diffusion) may govern slide dynamics. A new analysis of 14 yrs of discharge and sediment concentration data for the Eel River indicates that the characteristic mid-winter timing of earthflow acceleration corresponds with increased suspended concentration values, suggesting that the seasonal onset of landslide motion each year may be reflected in the export of sediments to the continental margin. The vast majority of active slides exhibit gullied surfaces and the gully networks, which are also seasonally active, may facilitate sediment export although the proportion of material produced by this pathway is poorly known. Along Kekawaka Creek, a prominent tributary to the Eel River, new analyses of catchment-averaged erosion rates derived from cosmogenic radionuclides reveal rapid erosion (0.76 mm/yr) below a prominent knickpoint and slower erosion (0.29 mm/yr) upstream. Such knickpoints are frequently observed in Eel tributaries and are usually comprised of massive (> 10 m) interlocking resistant boulders that likely persist in the landscape for long periods of time (> 105 yr). Upstream of these knickpoints, active landslides tend to be less frequent and average slope angles are slightly gentler than in downstream areas, which indicates that landslide density and average slope angle appear to increase with erosion rate. Lastly, we synthesize evidence for the role of large, catastrophic landslides in regulating sediment flux and landscape form. The emergence of resistant blocks within the mélange bedrock has promoted large catastrophic slides that have dammed the Eel River and perhaps generated outburst events in the past. The frequency and impact of these landslide dams likely depend on the spatial and size distributions of resistant blocks relative to the width and drainage area of adjacent valley networks. Overall, our findings demonstrate that landslides within the Eel River catchment do not occur randomly, but instead exhibit spatial and temporal patterns related to baselevel lowering, climate forcing, and lithologic variations. Combined with recent landscape evolution models that incorporate landslides, these results provide predictive capability for estimating erosion rates and managing hazards in mountainous regions

Advanced Geoscience Remote Sensing

Nowadays, advanced remote sensing technology plays tremendous roles to build a quantitative and comprehensive understanding of how the Earth system operates. The advanced remote sensing technology is also used widely to monitor and survey the natural disasters and man-made pollution. Besides, telecommunication is considered as precise advanced remote sensing technology tool. Indeed precise usages of remote sensing and telecommunication without a comprehensive understanding of mathematics and physics. This book has three parts (i) microwave remote sensing applications, (ii) nuclear, geophysics and telecommunication; and (iii) environment remote sensing investigations

Development of a geological model useful for the study of the natural hazards in urban environments. An example from the eastern sector of Rome (Italy)

Detailed knowledge of the subsoil setting is an extremely important issue for a correct risk reduction policy, especially when dealing with urban areas hosting cultural heritage, which enhance risk conditions even at low geo-hazard levels, as in the case of Rome. In general, the reliability of risk assessments related to geo-hazards is strictly dependent on the resolution of the reference geological model. The study presented here exemplifies an integrated methodology aimed at refining the knowledge of the geological setting in unique urban environments, such as the city of Rome, where canonical approaches are limited by the scarcity of outcrops and ad-hoc geognostic surveys may be expensive and time-consuming. The methodology used in the study is based on a critical review of available geological, stratigraphic, archeological and historical-archival data. The integration of such data, properly stored, managed and analysed in a GIS environment, made it possible to: i) better frame the geological setting of a wide sector of the eastern part of Rome; and, in particular, ii) focus on buried natural morphologies (i.e. valleys) strongly modified by progressive urbanisation that determined their filling with huge thickness of backfills, which often represent a critical geotechnical issue. A detailed geological model was thus developed. The model shows slight but significant differences with respect to already available official maps, emphasising the need for carrying out in-depth analyses of already existing data from different sources, in order to collect thematic data to be used for effective land management policies

Spaceborne radar observations: A guide for Magellan radar-image analysis

Geologic analyses of spaceborne radar images of Earth are reviewed and summarized with respect to detecting, mapping, and interpreting impact craters, volcanic landforms, eolian and subsurface features, and tectonic landforms. Interpretations are illustrated mostly with Seasat synthetic aperture radar and shuttle-imaging-radar images. Analogies are drawn for the potential interpretation of radar images of Venus, with emphasis on the effects of variation in Magellan look angle with Venusian latitude. In each landform category, differences in feature perception and interpretive capability are related to variations in imaging geometry, spatial resolution, and wavelength of the imaging radar systems. Impact craters and other radially symmetrical features may show apparent bilateral symmetry parallel to the illumination vector at low look angles. The styles of eruption and the emplacement of major and minor volcanic constructs can be interpreted from morphological features observed in images. Radar responses that are governed by small-scale surface roughness may serve to distinguish flow types, but do not provide unambiguous information. Imaging of sand dunes is rigorously constrained by specific angular relations between the illumination vector and the orientation and angle of repose of the dune faces, but is independent of radar wavelength. With a single look angle, conditions that enable shallow subsurface imaging to occur do not provide the information necessary to determine whether the radar has recorded surface or subsurface features. The topographic linearity of many tectonic landforms is enhanced on images at regional and local scales, but the detection of structural detail is a strong function of illumination direction. Nontopographic tectonic lineaments may appear in response to contrasts in small-surface roughness or dielectric constant. The breakpoint for rough surfaces will vary by about 25 percent through the Magellan viewing geometries from low to high Venusian latitudes. Examples of anomalies and system artifacts that can affect image interpretation are described

STOCHASTIC ASSESSMENT OF LANDSLIDE SUSCEPTIBILITY ALONGSIDE “VÍA AL LLANO” HIGHWAY, COLOMBIA

Le frane frequenti lungo la "Via al Llano", una delle più importanti autostrade colombiane, interrompono regolarmente il traffico. Questa rotta cruciale collega Bogotá, la capitale della Colombia, con Villavicencio, la capitale dello stato di Meta, facilitando il trasporto di beni agricoli e industriali e promuovendo lo sviluppo economico regionale attraverso il turismo. La regione circostante la "Via al Llano" è caratterizzata da caratteristiche geologiche come pieghe, faglie, giunti e affioramenti di diverse litologie ed età. Inoltre, pendii ripidi, deforestazione, depositi non consolidati, alte precipitazioni annuali e un paesaggio fortemente sezionato contribuiscono ulteriormente al verificarsi di frane. Pertanto, identificare accuratamente le aree ad alto rischio di frana, in particolare dove la strada interseca, attraverso la modellazione della suscettibilità alle frane, è imperativo.Nonostante studi precedenti, che si basavano prevalentemente sulla modellazione predittiva, risultassero in una correlazione insufficiente con la strada. Pertanto, l'obiettivo di questo studio è migliorare la risoluzione spaziale suddividendo l'area di studio nei cinque comuni attraversati dalla strada: Chipaque, Caqueza, Quetame, Guayabetal e Villavicencio. Per affrontare la complessità dell'area, lo studio ha prima valutato la fattibilità di sviluppare inventari automatici utilizzando dati radiometrici da immagini satellitari ottiche e radar attraverso la piattaforma Google Earth Engine (GEE). In secondo luogo, sono state create mappe pluviometriche dell'area interpolando 15 anni di dati sulle precipitazioni. Inoltre, sono state generate anche mappe geomorfologiche per ciascuno dei cinque comuni, rappresentando un risultato significativo di questa tesi. Queste mappe forniscono informazioni precedentemente non disponibili, essenziali per comprendere i processi naturali regionali e stabilire elementi fondamentali per mappe di rischio e pericolo.Di conseguenza, lo studio ha impiegato la tecnica delle Splines Adattive di Regressione Multivariata (MARS) per modellare la relazione tra le frane e le variabili predittive come altitudine, angolo di pendenza, esposizione, curvatura, litologia, precipitazioni, NDVI. I modelli sono stati rigorosamente calibrati e validati utilizzando dieci campioni di addestramento e dieci campioni di test, valutando le loro prestazioni predittive tramite la curva ROC (AUC). I nostri risultati indicano che le frane sono più probabili intorno ai corsi d'acqua affluenti del Rio Negro, con variabili chiave -Indice di Posizione Topografica (TPI), Indice di Vegetazione Normalizzato (NDVI), elevazione (ELE), precipitazioni (PLV), pendenza (SLO) e litologia (LTL)- che contribuiscono ad accuratezze predittive che vanno dal 74% all'83%.Frequent landslides along the "Via al Llano”, one of the most important Colombian highways, regularly disrupt traffic. This crucial route connects Bogotá, the capital of Colombia, with Villavicencio, the capital of Meta state, facilitating the transportation of agricultural and industrial goods and promoting regional economic development through tourism. The region surrounding the “Via al Llano” is characterized by geological features such as folds, faults, joints, and outcrops of diverse lithologies and ages. Additionally, steep slopes, deforestation, unconsolidated deposits, high annual rainfall, and a highly dissected landscape further contribute to landslides occurrences. Therefore, accurately identifying high-risk landslide areas, particularly where the road intersects, through landslide susceptibility modeling, is imperative.Despite previous studies, which predominantly relied on predictive modeling, resulting in insufficient correlation with the road. Therefore, the aim of this study is to enhance spatial resolution by subdividing the study area into the five municipalities traversed by the road: Chipaque, Caqueza, Quetame, Guayabetal, and Villavicencio. To address the complexity of the area, the study first assessed the feasibility of developing automatic inventories using radiometric data from optical and radar satellite images through the Google Earth Engine (GEE) platform. Secondly, pluviometry maps of the area were created by interpolating 15 years of rainfall data. Additionally, geomorphological maps for each of the five municipalities were also generated, representing a significant outcome of this thesis. These maps provide previously unavailable information, essential for understanding regional natural processes and establishing foundational elements for risk and hazard maps. Consequently, the study employed the Multivariate Adaptive Regression Splines (MARS) technique to model the relationship between landslides and predictor variables such as elevation, slope angle, aspect, curvature, lithology, precipitation, NDVI. The models were rigorously calibrated and validated using ten training and ten test samples, evaluating their predictive performance by the Receiver Operating Curve (AUC). Our findings indicate that landslides are most probable around the tributary streams of the Rio Negro, with key variables -Topographic Position Index (TPI), Normalized Difference Vegetation Index (NDVI), elevation (ELE), precipitation (PLV), slope (SLO), and lithology (LTL)- contributing to predictive accuracies ranging from 74% to 83%

Dense and long-term monitoring of Earth surface processes with passive RFID -- a review

Billions of Radio-Frequency Identification (RFID) passive tags are produced yearly to identify goods remotely. New research and business applications are continuously arising, including recently localization and sensing to monitor earth surface processes. Indeed, passive tags can cost 10 to 100 times less than wireless sensors networks and require little maintenance, facilitating years-long monitoring with ten's to thousands of tags. This study reviews the existing and potential applications of RFID in geosciences. The most mature application today is the study of coarse sediment transport in rivers or coastal environments, using tags placed into pebbles. More recently, tag localization was used to monitor landslide displacement, with a centimetric accuracy. Sensing tags were used to detect a displacement threshold on unstable rocks, to monitor the soil moisture or temperature, and to monitor the snowpack temperature and snow water equivalent. RFID sensors, available today, could monitor other parameters, such as the vibration of structures, the tilt of unstable boulders, the strain of a material, or the salinity of water. Key challenges for using RFID monitoring more broadly in geosciences include the use of ground and aerial vehicles to collect data or localize tags, the increase in reading range and duration, the ability to use tags placed under ground, snow, water or vegetation, and the optimization of economical and environmental cost. As a pattern, passive RFID could fill a gap between wireless sensor networks and manual measurements, to collect data efficiently over large areas, during several years, at high spatial density and moderate cost.Comment: Invited paper for Earth Science Reviews. 50 pages without references. 31 figures. 8 table