Runoff-generated debris flows: Observation of initiation conditions and erosion–deposition dynamics along the channel at Cancia (eastern Italian Alps)     

Alessandro Simoni  Martino Bernard  Matteo Berti  Mauro Boreggio  Stefano Lanzoni  Laura Maria Stancanelli  Carlo Gregoretti 《地球表面变化过程与地形》2020,45(14):3556-3571

In the Dolomitic region, abundant coarse hillslope sediment is commonly found at the toe of rocky cliffs. Ephemeral channels originate where lower permeability bedrock surfaces concentrate surface runoff. Debris flows initiate along such channels following intense rainfall and determine the progressive erosion and deepening of the channels. Sediment recharge mechanisms include rock fall, dry ravel processes and channel-bank failures. Here we document debris flow activity that took place in an active debris flow basin during the year 2015. The Cancia basin is located on the southwestern slope of Mount Antelao (3264 m a.s.l.) in the dolomitic region of the eastern Italian Alps. The 2.5 km² basin is incised in dolomitic limestone rocks. The data consist of repeated topographic surveys, distributed rainfall measurements, time-lapse (2 s) videos of two events and pore pressure measurements in the channel bed. During July and August 2015, two debris flow events occurred, following similarly intense rainstorms. We compared rainfall data to existing rainfall triggering thresholds and simulated the hydrological response of the headwater catchment with a distributed model in order to estimate the total and peak water discharge. Our data clearly illustrate how debris entrainment along the channel is the main contributor to the overall mobilized volume and that erosion is dominant when the channel slope exceeds 16°. Further downstream, sediment accumulation and depletion occurred alternately for the two successive events, indicating that sediment availability along the channel also influences the flow behaviour along the prevailing-transport reach. The comparison between monitoring data, topographical analysis and hydrological simulation allows the estimation of the average solid concentration of the two events and suggests that debris availability has a significant influence on the debris flow volume. © 2020 John Wiley & Sons, Ltd.  相似文献   

Separation of PP- and PS-wave reflected seismic data using two-dimensional finite offset common-reflection-surface traveltime approximation     

Raphael Di Carlo Silva dos Santos  João Carlos Ribeiro Cruz  Manuel de Jesus dos Santos Costa 《Geophysical Prospecting》2020,68(7):2046-2063

Recently, the interest in PS-converted waves has increased for several applications, such as sub-basalt layer imaging, impedance estimates and amplitude-versus-offset analysis. In this study, we consider the problem of separation of PP- and PS-waves from pre-stacked multicomponent seismic data in two-dimensional isotropic medium. We aim to demonstrate that the finite-offset common-reflection-surface traveltime approximation is a good alternative for separating PP- and PS-converted waves in common-offset and common shot configurations by considering a two-dimensional isotropic medium. The five parameters of the finite-offset common-reflection-surface are firstly estimated through the inversion methodology called very fast simulated annealing, which estimates all parameters simultaneously. Next, the emergence angle, one of the inverted parameters, is used to build an analytical separation function of PP and PS reflection separation based on the wave polarization equations. Once the PP- and PS-converted waves were separated, the sections are stacked to increase the signal-to-noise ratio using the special curves derived from finite-offset common-reflection-surface approximation. We applied this methodology to a synthetic dataset from simple-layered to complex-structured media. The numerical results showed that the inverted parameters of the finite offset common-reflection-surface and the separation function yield good results for separating PP- and PS-converted waves in noisy common-offset and common shot gathers.  相似文献   

DISOLV: A Python Package for the Interpretation of Borehole Dilution Tests     

Sarah L. Collins  Marco Bianchi 《Ground water》2020,58(5):805-812

Single borehole dilution tests (SBDTs) are an inexpensive but effective technique for hydrogeological characterization of hard-rock aquifers. We present a freely available, easy-to-use, open-source Python package, DISOLV, for plotting, analyzing, and modeling SBDT data. DISOLV can significantly reduce the time spent interpreting field data by helping to identify flowing fractures intersecting the borehole and estimate the corresponding flow rates. DISOLV is successfully benchmarked against two analytical solutions. We also present an example application to real data collected in a borehole in a crystalline basement aquifer in southern India.  相似文献   

Early Jurassic palaeoenvironments in the Surat Basin,Australia – marine incursion into eastern Gondwana     

Andrew D. La Croix  Jianhua He  Valeria Bianchi  Jiahao Wang  Sebastian Gonzalez  Jim R. Undershultz 《Sedimentology》2020,67(1):457-485

Interpretations of palaeodepositional environments are important for reconstructing Earth history. Only a few maps showing the Jurassic depositional environments in eastern Australia currently exist. Consequently, a detailed understanding of the setting of Australia in Gondwana is lacking. Core, wireline logs, two-dimensional and three-dimensional seismic from the Precipice Sandstone and Evergreen Formation in the Surat Basin have been used to construct maps showing the evolution of depositional environments through the Early Jurassic. The results indicate the succession consists of three third-order sequences (Sequence 1 to Sequence 3) that were controlled by eustatic sea level. The lowstand systems tract in Sequence 1 comprises braidplain deposits, confined to a fairway that parallels the basin centre. The strata were initially deposited in two sub-basins, with rivers flowing in different orientations in each sub-basin. The transgressive systems tract of Sequence 1 to lowstand systems tract of Sequence 3 is dominated by fluvio–deltaic systems infilling a single merged basin centre. Finally, the transgressive and highstand systems tracts of Sequence 3 show nearshore environments depositing sediment into a shallow marine basin. In the youngest part of this interval, ironstone shoals are the most conspicuous facies, the thickness and number of which increase towards the north and east. This study interprets a corridor to the open ocean through the Clarence–Moreton Basin, or the Carpentaria and Papuan basins, evidence of which has been eroded. These results challenge a commonly held view that eastern Australia was not influenced by eustasy, and propose a more dynamic palaeogeographic setting comprising a mixture of fluvial, deltaic and shallow marine sedimentary environments. This work can be used to unravel the stratigraphic relationships between Mesozoic eastern Australian basins, or in other basins globally as an analogue for understanding the complex interplay of paralic depositional systems in data poor areas.  相似文献   

Ecotoxicological evaluation of dredged sediments from Rodrigo de Freitas Lagoon (Rio de Janeiro State,Brazil) using bioassays with earthworms and collembolans     

Mariana Vezzone  Ricardo Cesar  Helena Polivanov  Aline Serrano  Danielle Siqueira  Leticia Abreu  Miriam Bianchi  Maria Elizabeth Correia  Zuleica Castilhos  Tácio de Campos 《Environmental Earth Sciences》2018,77(21):743

The toxicity and metal bioavailability were studied in dredged sediments from Rodrigo de Freitas Lagoon (Rio de Janeiro, RJ, Brazil) using acute and avoidance tests with Eisenia andrei, and reproduction tests with Folsomia candida. The sediment was mixed with an artificial soil, and two natural soils (ferralsol and chernosol—representative Brazilian tropical soils) to obtain the following doses: 1, 3, 6, 12, 18, 24 and 30%. Total metal concentrations were determined in the sediment to support the interpretation of ecotoxicological data. Metal concentrations in the mixtures were in agreement with the threshold limits established by Brazilian law. However, significant avoidance responses were found on doses ≥?3% and were the most sensitive endpoint. Earthworm mortality found in artificial soil mixtures (LC50?=?3.9) suggests higher toxicity levels than those obtained in ferralsol (LC50?=?7.6%) and chernosol (11.0%) treatments. Earthworm mortality, avoidance responses and collembolan reproduction levels found in ferralsol mixtures (LC50?=?9.2; avoidance EC50?=?2.3%; reproduction EC50?=?2.8%) were higher compared to chernosol treatments (LC50?=?11.0%; avoidance EC50?=?4.3%; reproduction EC50?=?4.9%). The reduction of toxicity levels in chernosol mixtures is probably due to the abundance of expansive clay minerals in chernosols with capacity of adsorbing metals and other xenobiotic substances from soil pore water, decreasing metal bioavailability. Finally, threshold limits defined by Brazilian legislation for soil quality and land disposal of dredged sediments are not sufficient to prevent noxious effects on soil fauna and should be complemented with a preliminary ecotoxicological evaluation.  相似文献   

Impact of model complexity and multi-scale data integration on the estimation of hydrogeological parameters in a dual-porosity aquifer     

Elena Tamayo-Mas  Marco Bianchi  Majdi Mansour 《Hydrogeology Journal》2018,26(6):1917-1933

This study investigates the impact of model complexity and multi-scale prior hydrogeological data on the interpretation of pumping test data in a dual-porosity aquifer (the Chalk aquifer in England, UK). In order to characterize the hydrogeological properties, different approaches ranging from a traditional analytical solution (Theis approach) to more sophisticated numerical models with automatically calibrated input parameters are applied. Comparisons of results from the different approaches show that neither traditional analytical solutions nor a numerical model assuming a homogenous and isotropic aquifer can adequately explain the observed drawdowns. A better reproduction of the observed drawdowns in all seven monitoring locations is instead achieved when medium and local-scale prior information about the vertical hydraulic conductivity (K) distribution is used to constrain the model calibration process. In particular, the integration of medium-scale vertical K variations based on flowmeter measurements lead to an improvement in the goodness-of-fit of the simulated drawdowns of about 30%. Further improvements (up to 70%) were observed when a simple upscaling approach was used to integrate small-scale K data to constrain the automatic calibration process of the numerical model. Although the analysis focuses on a specific case study, these results provide insights about the representativeness of the estimates of hydrogeological properties based on different interpretations of pumping test data, and promote the integration of multi-scale data for the characterization of heterogeneous aquifers in complex hydrogeological settings.  相似文献   

Structural performance of automated multi-depth shuttle warehouses (AMSWs) under low-to-moderate seismic actions     

Kondratenko  Aleksei  Kanyilmaz  Alper  Castiglioni  Carlo Andrea  Morelli  Francesco  Kohrangi  Mohsen 《Bulletin of Earthquake Engineering》2022,20(2):1247-1295

Bulletin of Earthquake Engineering - Automated Multi-Depth Shuttle Warehouses (AMSWs) are compact storage systems that provide a large surface occupation and therefore maximum storage density....  相似文献   

Integration of earth observation and census data for mapping a multi-temporal flood vulnerability index: a case study on Northeast Italy     

Cian  Fabio  Giupponi  Carlo  Marconcini  Mattia 《Natural Hazards》2021,106(3):2163-2184

Climate sciences foresee a future where extreme weather events could happen with increased frequency and strength, which would in turn increase risks of floods (i.e. the main source of losses in the world). The Mediterranean basin is considered a hot spot in terms of climate vulnerability and risk. The expected impacts of those events are exacerbated by land-use change and, in particular, by urban growth which increases soil sealing and, hence, water runoff. The ultimate consequence would be an increase of fatalities and injuries, but also of economic losses in urban areas, commercial and productive sites, infrastructures and agriculture. Flood damages have different magnitudes depending on the economic value of the exposed assets and on level of physical contact with the hazard. This work aims at proposing a methodology, easily customizable by experts’ elicitation, able to quantify and map the social component of vulnerability through the integration of earth observation (EO) and census data with the aim of allowing for a multi-temporal spatial assessment. Firstly, data on employment, properties and education are used for assessing the adaptive capacity of the society to increase resilience to adverse events, whereas, secondly, coping capacity, i.e. the capacities to deal with events during their manifestation, is mapped by aggregating demographic and socio-economic data, urban growth analysis and memory on past events. Thirdly, the physical dimension of exposed assets (susceptibility) is assessed by combining building properties acquired by census data and land-surface characteristics derived from EO data. Finally, the three components (i.e. adaptive and coping capacity and susceptibility) are aggregated for calculating the dynamic flood vulnerability index (FVI). The approach has been applied to Northeast Italy, a region frequently hit by floods, which has experienced a significant urban and economic development in the past decades, thus making the dynamic study of FVI particularly relevant. The analysis has been carried out from 1991 to 2016 at a 5-year steps, showing how the integration of different data sources allows to produce a dynamic assessment of vulnerability, which can be very relevant for planning in support of climate change adaptation and disaster risk reduction.

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A novel methodological approach for land subsidence prediction through data assimilation techniques     

Gazzola  Laura  Ferronato  Massimiliano  Frigo  Matteo  Janna  Carlo  Teatini  Pietro  Zoccarato  Claudia  Antonelli  Massimo  Corradi  Anna  Dacome  Maria Carolina  Mantica  Stefano 《Computational Geosciences》2021,25(5):1731-1750

Computational Geosciences - Anthropogenic land subsidence can be evaluated and predicted by numerical models, which are often built over deterministic analyses. However, uncertainties and...  相似文献   

Robust numerical implementation of a 3D rate-dependent model for reservoir geomechanical simulations     

Giovanni Isotton  Pietro Teatini  Massimiliano Ferronato  Carlo Janna  Nicolò Spiezia  Stefano Mantica  Giorgio Volonte 《国际地质力学数值与分析法杂志》2019,43(18):2752-2771

A 3D elasto-plastic rate-dependent model for rock mechanics is formulated and implemented into a Finite Element (FE) numerical code. The model is based on the approach proposed by Vermeer and Neher (A soft soil model that accounts for creep. In: Proceedings of the International Symposium “Beyond 2000 in Computational Geotechnics,” pages 249-261, 1999). An original strain-driven algorithm with an Inexact Newton iterative scheme is used to compute the state variables for a given strain increment.The model is validated against laboratory measurements, checked on a simplified test case, and used to simulate land subsidence due to groundwater and hydrocarbon production. The numerical results prove computationally effective and robust, thus allowing for the use of the model on real complex geological settings.  相似文献