D. Di Curzio
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10 records found
1
Impact and evaluation of potential implications of coastal plains on soil greenhouse gas emissions
Insights from the Sibari Coastal Plain (Calabria, Southern Italy)
The work aims to estimate natural greenhouse gas emissions from soils in the Sibari Coastal Plain (Southern Italy), to understand (i) the contribution in terms of the total amount of CO2 and CH4 emitted in non-volcanic areas, (ii) the relationship among emitted gas, land use, organic matter and tectonic structures, and (iii) their potential environmental implications. Data were elaborated with statistical and geostatistical methods to separate the different populations and obtain prediction and probability maps. Methane fluxes had values consistently below the detection limit (0.032 g ∙ m−2 ∙ d−1) except for three measurement points randomly distributed along the plain. Statistical and geostatistical methods allowed to discriminate three main CO2 flux populations: (i) high-flux population (Pop. B - mean value of 63.65 g ∙ m−2 ∙ d−1), located near the mouth of the Crati River and related to the massive presence of buried organic matter in the form of peat; (ii) medium-flux population (Pop. A2 - mean value of 8.37 g ∙ m−2 ∙ d−1) which is the result of soil respiration, and (iii) low-flux population (Pop. A1 - mean value of 1.85 g ∙ m−2 ∙ d−1) due to areas where low permeability or increases in saturated aquifer thickness may control the overall flux. In the study area, a total CO2 emission of about 2671 t ∙ d−1 was calculated, which, if compared to the average total flux expected for simple soil respiration (1284 t ∙ d−1), represents a non-negligible value in the total Carbon balance. Finally, the comparison with representative normalized fluxes from volcanic and non-volcanic areas confirms the critical role of coastal plains in total atmospheric CO2 emissions. The proposed approach can be applied to areas with comparable or different geological and climatic settings to trace their contribution in terms of greenhouse gas release to the atmosphere.
Estimating the spatial distribution of hydromechanical properties in the investigated subsoil by defining an Engineering Geological Model (EGM) is crucial in urban planning, geotechnical designing and mining activities. The EGM is always affected by (i) the spatial variability of the measured properties of soils and rocks, (ii) the uncertainties related to measurement and spatial estimation, as well as (iii) the propagated uncertainty related to the analytical formulation of the transformation equation. The latter is highly impactful on the overall uncertainty when design/target variables cannot be measured directly (e.g., in the case of piezocone Cone Penetration Test–CPTu measurements). This paper focuses on assessing the Propagated Uncertainty (PU) when defining 3D EGMs of three CPTu-derived design/target variables: the undrained shear resistance (su), the friction angle (φ′), and the hydraulic conductivity (k). We applied the Sequential Gaussian Co-Simulation method (SGCS) to the measured profiles of tip (qc) and shaft resistance (fs), and the pore pressure (u2), measured through CPTus in a portion of Bologna district (Italy). First, we calculated 1000 realizations of the measured variables using SGCS; then, we used the available transformation equations to obtain the same number of realizations of su, φ′, and k. The results showed that PU is larger when the transformation equation used to obtain the design/target variable is very complex and dependent on more than one input variable, such as in the case of k. Instead, linear (i.e., for su) or logarithmic (i.e., for φ′) transformation functions do not contribute to the overall uncertainty of results considerably.
Estimating a Reliable Water Budget at A Basin Scale
A Comparison between the Geostatistical and Traditional Methods (Foro River Basin, Central Italy)
To perform a geotechnical reliable design, the spatial variability and the uncertainties related to the adopted engineering geological model (EGM) must be taken into account. However, any conceived EGM is characterized by uncertainties covering (1) the bias in the mathematical expression that transforms the measured parameters into design ones; and (2) the uncertainty associated with the variability of the soil and rock parameters in the prediction equations. Hereinafter, the sequential Gaussian co-simulation method (SGCS) has been applied to propagate the uncertainty in the calculation of the undrained shear resistance su from measured CPTu profiles (i.e., qc, fs, u2) through a linear model of co-regionalization. The studied area is located in the Po River alluvial plain (Bologna Province, Italy), where the mixture of silts, sands, and clays gets thicknesses of hundreds of meters. These heterogeneous deposits have been mechanically characterized through a 3D EGM to be used in reliability-based designing.