ALBERT

Description: From the analysis of GPS monitoring data collected above gas fields in the Adriatic Sea, in a few cases subsidence responses have been observed not to directly correlate with the production trend. Such behavior, already described in the literature, may be due to several physical phenomena, ranging from simple delayed aquifer depletion to a much more complex time-dependent mechanical response of subsurface geomaterials to fluid withdrawal. In order to accurately reproduce it and therefore to be able to provide reliable forecasts, in the last years Eni has enriched its 3D finite element geomechanical modeling workflow by adopting an advanced constitutive model (Vermeer and Neher, 1999), which also considers the viscous component of the deformation. While the numerical implementation of such methodology has already been validated at laboratory scale and tested on synthetic hydrocarbon fields, the work herein presents its first application to a real gas field in the Adriatic Sea where the phenomenon has been observed. The results show that the model is capable to reproduce very accurately both GPS data and other available measurements. It is worth remarking that initial runs, characterized by the use of model parameter values directly obtained from the interpretation of mechanical laboratory tests, already provided very good results and only minor tuning operations have been required to perfect the model outcomes. Ongoing R&D projects are focused on a regional scale characterization of the Adriatic Sea basin in the framework of the Vermeer and Neher model approach.

Description: The use of numerical models for land subsidence prediction above producing hydrocarbon reservoirs has become a common and well-established practice since the early '90s. Usually, uncertainties in the deep rock behavior, which can affect the forecast capability of the models, have been taken into account by running multiple simulations with different constitutive laws and mechanical properties. Then, the most uncertain parameters were calibrated to reproduce available subsidence measurements. The objective of this work is to propose a novel methodological approach for land subsidence prediction and uncertainty quantification by integrating the available monitoring information in numerical models using ad hoc Data Assimilation techniques. The proposed approach allows to: (i) train the model with the available data and improve its accuracy as new information comes in, (ii) quantify the prediction uncertainty by providing confidence intervals and probability measures instead of deterministic outcomes, and (iii) identify the most appropriate rock constitutive model and geomechanical parameters. The methodology is tested in synthetic models of production from hydrocarbon reservoirs. The numerical experiments show that the proposed approach is a promising way to improve the effectiveness and reliability of land subsidence models.

Description: The numerical prediction of land subsidence above producing reservoirs can be affected by a number of uncertainties, related for instance to the deep rock constitutive behavior, geomechanical properties, boundary and forcing conditions, etc. The quality and the amount of the available observations can help reduce such uncertainties by constraining the numerical model outcome and providing more reliable estimates of the unknown governing parameters. In this work, we address the numerical simulation of land subsidence above a producing hydrocarbon field in the Northern Adriatic, Italy, by integrating the available monitoring data in the computational model with the aid of Data Assimilation strategies. A preliminary model diagnostic analysis, i.e. the χ2-test, allows for identifying the most appropriate forecast ensemble. Then, a Bayesian approach, i.e. the Red Flag technique, and a smoother formulation, i.e. the Ensemble Smoother, provide a significant reduction of the prior uncertainties. The experiment developed on a real-world gas field confirms that the integration of monitoring observations with classical geomechanical models is a valuable approach to improve the reliability of land subsidence predictions and to exploit in a systematic way the increasing amount of available measurement records.

Description: Land use influences the abundance and diversity of soil arthropods. The evaluation of the impact of different management strategies on soil quality is increasingly sought, and the determination of community structures of edaphic fauna can represent an efficient tool. In the area of Langhe (Piedmont, Italy), eight vineyards characterized for physical and chemical properties (soil texture, soil pH, total organic carbon, total nitrogen, calcium carbonate) were selected. We evaluated the effect of two types of crop management, organic and integrated pest management (IPM), on abundance and biodiversity of microarthropods living at the soil surface. Soil sampling was carried out in winter 2011 and spring 2012. All specimens were counted and determined up to the order level. The biodiversity analysis was performed using ecological indexes (taxa richness, dominance, Shannon–Wiener, Buzas and Gibson's evenness, Margalef, equitability, Berger–Parker), and the biological soil quality was assessed with the BSQ-ar index. The mesofauna abundance was affected by both the type of management and sampling time. On the whole, a higher abundance was in organic vineyards (N = 1981) than in IPM ones (N = 1062). The analysis performed by ecological indexes showed quite a high level of biodiversity in this environment, particularly in May 2012. Furthermore, the BSQ-ar values registered were similar to those obtained in preserved soils.

Description: Land use influences the abundance and diversity of soil arthropods. The evaluation of the impact of different management strategies on soil quality is increasingly requested. The determination of communities' structures of edaphic fauna can represent an efficient tool. In this study, in some vineyards in Piedmont (Italy), the effects of two different management systems, organic and integrated pest management (IPM), on soil biota were evaluated. As microarthropods living in soil surface are an important component of soil ecosystem interacting with all the other system components, a multi disciplinary approach was adopted by characterizing also some soil physical and chemical characteristics (soil texture, soil pH, total organic carbon, total nitrogen, calcium carbonate). Soil samplings were carried out on Winter 2011 and Spring 2012. All specimens were counted and determined up to the order level. The biological quality of the soil was defined through the determination of ecological indices, such as QBS-ar, species richness and indices of Shannon-Weaver, Pielou, Margalef and Simpson. The mesofauna abundance was affected by both the type of management and the soil texture. The analysis of microarthropod communities by QBS-ar showed higher values in organic than in IPM managed vineyards; in particular, the values registered in organic vineyards were similar to those characteristic of preserved soils.

Description: Deep earthwork activities carried out before vineyard plantation can severely upset soil profile properties. As a result, soil features in the root environment are often much more similar to those of the underlying substratum than those of the original profile. The time needed to recover the original soil functions is ecologically relevant and may strongly affect vine phenology and grape yield, particularly under organic viticulture. The general aim of this work was to investigate soil resilience after vineyard pre-planting earthworks. In particular, an old and a new vineyard, established on the same soil type, were compared over a five year period for soil chemical, physical, micro and mesobiological properties. The investigated vineyards (Vitis vinifera L., cv. Sangiovese) were located in the Chianti Classico district (Central Italy), on stony and calcareous soils and were not irrigated. The older vineyard was planted in 2000, after slope reshaping by bulldozing and back hoe ploughing down to about 0.8–1.0 m. The new vineyard was planted in 2011, after equivalent earthwork practices carried out in the summer of 2009. Both vineyards were organically managed and fertilized only with compost every autumn (1000 kg ha−1 per year). The new vineyard was cultivated by periodic tillage, while the old vineyard was managed with alternating grass-covered and tilled inter-rows. Soil samples were collected at 0–15 cm depth from the same plots of the new and old vineyards, during the springtime from 2010 to 2014. The old vineyard was sampled in both the tilled and the grass-covered swaths. According to the results from physical and chemical analyses, the new vineyard, during the whole 2010–2014 period, showed lower TOC, N, C/N and EC values, along with higher silt and total CaCO3 contents than the old vineyard, suggesting still evolving equilibrium conditions. The microarthropod analysis showed significantly different abundances and communities' structures, in relation to both vineyard and time, increasing with rain precipitations in the old vineyard. Though the euedaphic forms, well adapted to soil life, were always rare. Microbiological analysis revealed a different structure of eubacterial communities between old and new vineyard in the whole period. However, the DGGE similarity values of such communities increased of about 2.5% per year, suggesting that at least 3 years more are needed to compare intra- and inter-specific diversity of the two vineyards. In conclusion, the consequences of deep earthworks on soil chemical, micro and mesobiological properties were still evident after four years from planting, indicating that more time is necessary for the recovery of soil functions, probably longer than that needed to obtain an economic grape production.

Description: Deep earthwork activities carried out before vineyard plantation can severely affect soil profile properties. As a result, soil features in the root environment are often much more similar to those of the underlying substratum than those of the original profile. The time needed to recover the original soil functions is ecologically relevant and may strongly affect vine phenology and grape yield, particularly under organic viticulture. The general aim of this work was to investigate soil resilience after vineyard pre-planting earthworks. In particular, an old and a new vineyard, established on the same soil type, were compared over a 5-year period for soil chemical, physical, micro- and mesobiological properties. The investigated vineyards (Vitis vinifera L., cv. Sangiovese) were located in the Chianti Classico district (central Italy), on stony and calcareous soils, and were not irrigated. The older vineyard was planted in 2000, after slope reshaping by bulldozing and back-hoe ploughing down to about 0.8–1.0 m. The new vineyard was planted in 2011, after equivalent earthwork practices carried out in the summer of 2009. Both vineyards were organically managed, and they were fertilized with compost only every autumn (1000 kg ha−1 per year). The new vineyard was cultivated by periodic tillage, while the old vineyard was managed with alternating grass-covered and tilled inter-rows. Soil samples were collected at 0–15 cm depth from fixed locations in each vineyard every spring from 2010 to 2014. The old vineyard was sampled in both tilled and grass-covered inter-rows. According to the results from physical and chemical analyses, the new vineyard, during the whole 2010–2014 period, showed lower total organic carbon, total nitrogen, carbon to nitrogen ratio and electrical conductivity, along with higher silt and total CaCO3 contents than the old vineyard, suggesting still-evolving equilibrium conditions. The microarthropod analysis showed significantly different abundances and community structures, in relation to both vineyard and time. Rainfall appeared to have an enhancing effect on microarthropod abundance, but only in the old vineyard, where the biota was more structured than in the new one. The euedaphic forms, well adapted to soil life, were always rare. Microbiological analysis revealed a different structure of eubacterial communities between the old and the new vineyard in the whole period. However, the DGGE similarity values of these communities increased by about 2.5% per year, suggesting that at least 3 years more are needed to compare intra- and inter-specific diversity of the two vineyards. In conclusion, the consequences of deep earthworks on soil chemical, micro- and mesobiological properties were still evident 4 years after planting, indicating that more time is necessary for the recovery of soil functions, probably longer than the time needed to reach a state of economically viable grape production.

Description: The Dolomite Alps of northeastern Italy experience debris flows with great frequency during the summer months. An ample supply of unconsolidated material on steep slopes and a summer season climate regime characterized by recurrent thunderstorms combine to produce an abundance of these destructive hydrogeologic events. In the past debris flow events have been studied primarily in the context of their geologic and geomorphic characteristics. The atmospheric contribution to these mass wasting events has been limited to recording rainfall and developing intensity thresholds for debris mobilization. This study aims to expand the examination of atmospheric processes that preceded both locally intense convective rainfall (LICR) and debris flows in the Dolomite region. 500 hPa pressure level plots of geopotential heights were constructed for a period of three days prior to debris flow events to gain insight into the synoptic scale processes which provide an environment conducive to LICR in the Dolomites. Cloud-to-ground (CG) lightning flash data recorded at the meso-scale were incorporated to assess the convective environment proximal to debris flow source regions. Twelve events were analyzed and from this analysis three common synoptic scale circulation patterns were identified. Evaluation of CG flashes at smaller spatial and temporal scales illustrated that convective processes vary in their production of CG flashes (total number) and the spatial distribution of flashes can also be quite different between events over longer periods. During the 60 min interval immediately preceding debris flow a majority of cases exhibited spatial and temporal collocation of LICR and CG flashes. Also a number of CG flash parameters were found to be significantly correlated to rainfall intensity prior to debris flow initiation.

Description: The Dolomite Alps of northeastern Italy experience debris flows with great frequency during the summer months. An ample supply of unconsolidated material on steep slopes and a summer season climate regime characterized by recurrent thunderstorms combine to produce an abundance of these destructive hydro-geologic events. In the past, debris flow events have been studied primarily in the context of their geologic and geomorphic characteristics. The atmospheric contribution to these mass-wasting events has been limited to recording rainfall and developing intensity thresholds for debris mobilization. This study aims to expand the examination of atmospheric processes that preceded both locally intense convective rainfall (LICR) and debris flows in the Dolomite region. 500 hPa pressure level plots of geopotential heights were constructed for a period of 3 days prior to debris flow events to gain insight into the synoptic-scale processes which provide an environment conducive to LICR in the Dolomites. Cloud-to-ground (CG) lightning flash data recorded at the meso-scale were incorporated to assess the convective environment proximal to debris flow source regions. Twelve events were analyzed and from this analysis three common synoptic-scale circulation patterns were identified. Evaluation of CG flashes at smaller spatial and temporal scales illustrated that convective processes vary in their production of CF flashes (total number) and the spatial distribution of flashes can also be quite different between events over longer periods. During the 60 min interval immediately preceding debris flow a majority of cases exhibited spatial and temporal colocation of LICR and CG flashes. Also a number of CG flash parameters were found to be significantly correlated to rainfall intensity prior to debris flow initiation.

Description: The design of efficient hydrological risk mitigation strategies and their subsequent implementation relies on a careful vulnerability analysis of the elements exposed. Recently, extensive research efforts were undertaken to develop and refine empirical relationships linking the structural vulnerability of buildings to the impact forces of the hazard processes. These empirical vulnerability functions allow estimating the expected direct losses as a result of the hazard scenario based on spatially explicit representation of the process patterns and the elements at risk classified into defined typological categories. However, due to the underlying empiricism of such vulnerability functions, the physics of the damage-generating mechanisms for a well-defined element at risk with its peculiar geometry and structural characteristics remain unveiled, and, as such, the applicability of the empirical approach for planning hazard-proof residential buildings is limited. Therefore, we propose a conceptual assessment scheme to close this gap. This assessment scheme encompasses distinct analytical steps: modelling (a) the process intensity, (b) the impact on the element at risk exposed and (c) the physical response of the building envelope. Furthermore, these results provide the input data for the subsequent damage evaluation and economic damage valuation. This dynamic assessment supports all relevant planning activities with respect to a minimisation of losses, and can be implemented in the operational risk assessment procedure.