Hydrological control of soil thickness spatial variability on the initiation of rainfall-induced shallow landslides using a three-dimensional model

Thickness and stratigraphic settings of soils covering slopes potentially control susceptibility to initiation of rainfall-induced shallow landslides due to their local effect on slope hydrological response. Notwithstanding the relevance of the assessment of hazard to shallow landsliding at a distributed scale by approaches based on a coupled modelling of slope hydrological response and slope stability, the spatial variability of soil thickness and stratigraphic settings are factors poorly considered in the literature. Under these premises, this paper advances the well-known case study of rainfall-induced shallow landslides involving ash-fall pyroclastic soils covering the peri-Vesuvian mountains (Campania, southern Italy). In such a unique geomorphological setting, the soil covering is formed by alternating loose ash-fall pyroclastic deposits and paleosols, with high contrasts in hydraulic conductivity and total thickness decreasing as the slope angle increases, thus leading to the establishment of lateral flow and an increase of pore water pressure in localised sectors of the slope where soil horizon thickness is less. In particular, we investigate the effects, on hillslope hydrological regime and slope stability, of irregular bedrock topography, spatial variability of soil thickness and vertical hydraulic heterogeneity of soil horizons, by using a coupled three-dimensional hydrological and a probabilistic infinite slope stability model. The modelling is applied on a sample mountain catchment, located on Sarno Mountains (Campania, southern Italy), and calibrated using physics-based rainfall thresholds derived from the literature. The results obtained under five simulated constant rainfall intensities (2.5, 5, 10, 20 and 40 mm h−1) show an increase of soil pressure head and major failure probability corresponding to stratigraphic and morphological discontinuities, where a soil thickness reduction occurs. The outcomes obtained from modelling match the hypothesis of the formation of lateral throughflow due to the effect of intense rainfall, which leads to the increase of soil water pressure head and water content, up to values of near-saturation, in narrow zones of the slope, such as those of downslope reduction of total soil thickness and pinching out of soil horizons. The approach proposed can be conceived as a further advance in the comprehension of slope hydrological processes at a detailed scale and their effects on slope stability under given rainfall and antecedent soil hydrological conditions, therefore in predicting the most susceptible areas to initiation of rainfall-induced shallow landslides and the related I-D rainfall thresholds. Results obtained demonstrate the occurrence of a slope hydrological response depending on the spatial variability of soil thickness and leading to focus slope instability in specific slope sectors. The approach proposed is conceived to be potentially exportable to other slope environments for which a spatial modelling of soil thickness would be possible

Probabilistic approaches for assessing rainfall thresholds triggering shallow landslides. The study case of the peri-vesuvian area (Southern Italy)

Ash-fall pyroclastic soil deposits covering steep carbonate slopes in the peri-Vesuvian area (southern Italy) are periodically involved in shallow landslides (about 700 events were recorded during the last three centuries, as reported by CASCINI et alii, 2008), triggered by intense and/or prolonged rainfall events, which evolve as catastrophic debris flows. In the last decades, many studies have been focused on estimating reliable relationships among the triggering of shallow landslides and the amount and duration of rainfall events, as well as the role played by antecedent soil hydrological conditions. Results of these studies have been expected to give information on temporal hazard to landslide onset to be used for setting a reliable early warning system. In this paper we present probabilistic approaches to assess rainfall thresholds triggering shallow landslides by classical empirical methods and to manage the uncertainties related to biases of data. At this scope, rainfall events related to the occurrence of debris flows along slopes of the Sarno and Lattari Mountains, known from chronicles of the last century, were analyzed by means of the empirical models of Intensity-Duration (I-D) (CAINE, 1980) and rainfall recorded in the day of the landslide occurrence (P) vs the antecedent cumulated rainfall (Pa) (CROZIER & EYLES, 1980). In order to limit and to assess uncertainties related to biases of rainfall data, a comparison with the regional probability model of high intensity rainfall, carried out in the framework of the VAPI Project (ROSSI & VILLANI, 1994) has been carried out. Moreover, rainfall data were processed by a bivariate logistic regression model resulting in the assessment of probability to landslide triggering, given an assumed rainfall event. The I-D empirical rainfall thresholds obtained by Caine model (1980) were compared to rainfall thresholds estimated by deterministic approaches (DE VITA et alii, 2013; NAPOLITANO et alii, 2016) showing a good match

Seasonal and event-based hydrological and slope stability modeling of pyroclastic fall deposits covering slopes in Campania (Southern Italy)

The pyroclastic fall deposits mantling mountain slopes in the Campania region (Southern Italy) represent one of the most studied geomorphological frameworks of the world regarding rainfall-induced debris flows threating urban areas. The proposed study focused on advancing knowledge about the hydrological response of pyroclastic fall coverings from the seasonal to event-based time scales, leading to the initiation of slope instability. The study was based on two consequential tasks. The first was the analysis of a six-year monitoring of soil pressure head carried out in a sample area of the Sarno Mountains, located above a debris flow initiation zone. The second was based on coupled hydrological and slope stability modeling performed on the physical models of slopes, which were reconstructed by empirical correlations between the slope angle, total thickness, and stratigraphic settings of pyroclastic fall deposits mantling slopes. The results obtained were: (a) The understanding of a soil pressure head regime of the volcaniclastic soil mantle, always ranging in unsaturated conditions and characterized by a strong seasonal variability depending on precipitation patterns and the life cycle of deciduous chestnut forest; and (b) the reconstruction through a deterministic approach of seasonal intensity-duration rainfall thresholds related to different morphological conditions

Impact of the laminar flame speed correlation on the results of a quasi-dimensional combustion model for Spark-Ignition engine

Abstract In the present study, the impact of the laminar flame speed correlation on the prediction of the combustion process and performance of a gasoline engine is investigated using a 1D numerical approach. The model predictions are compared with experimental data available for full- and part-load operations of a small-size naturally aspirated Spark-Ignition (SI) engine, equipped with an external EGR circuit. A 1D model of the whole engine is developed in the GT-Power™ environment and is integrated with refined sub-models of the in-cylinder processes. In particular, the combustion is modelled using the fractal approach, where the burning rate is directly related to the laminar flame speed. In this work, three laminar flame speed correlations are assessed, including both experimentally- and numerically-derived formulations, the latter resulting from the fitting of laminar flame speeds computed by a chemical kinetic solver. Each correlation is implemented within the combustion sub-model, which is properly tuned to reproduce the experimental performance of the engine at full load. Then, the reliability of the considered flame speed formulations is proved at part-loads, even under external EGR operations

Anthropogenic sinkholes of the city of Naples, Italy: an update

In recent years, the study of anthropogenic sinkholes in densely urbanized areas has attracted the attention of both researchers and land management entities. The city of Naples (Italy) has been frequently affected by processes generating such landforms in the last decades: for this reason, an update of the sinkhole inventory and a preliminary susceptibility estimation are proposed in this work. Starting from previous data, not modified since 2010, a total of 270 new events occurred in the period February 2010–June 2021 were collected through the examination of online newspapers, local daily reports, council chronicle news and field surveys. The final consistence of the updated inventory is of 458 events occurred between 1880 and 2021, distributed through time with an increasing trend in frequency. Spatial analysis of sinkholes indicates a concentration in the central sector of the city, corresponding to its ancient and historic centre, crossed by a dense network of underground tunnels and cavities. Cavity-roof collapse is confirmed as one of the potential genetic types, along with processes related to rainfall events and service lines damage. A clear correlation between monthly rainfall and the number of triggered sinkholes was identified. Finally, a preliminary sinkhole susceptibility assessment, carried out by Frequency Ratio method, confirms the central sector of city as that most susceptible to sinkholes and emphasizes the predisposing role of service lines, mostly in the outermost areas of the city

S100B is not a reliable prognostic index in paediatric TBI.

Pediatr Neurosurg. 2007;43(4):258-64

Development and evaluation of an in-vehicle information system

In this paper, the authors introduce an In-Vehicle Information System (IVIS) which will manage messages from a variety of Advanced Traveler Information Services (ATIS) devices which can be installed in a road vehicle. The IVIS serves as the interface between the driver and the driving information environment. Increasingly, aftermarket systems, such as routing and navigation aids, are becoming available which can be added to vehicles to aid in travel and/or the conduct of business in the vehicle. The installation of multiple devices, each with its own driver interface, increases the likelihood of driver distraction and thus the risk of an accident. The goal of this project is the development of a fully-integrated IVIS which will filter, prioritize and display highway and vehicle information safely and efficiently, while also providing an integrated driver interface to a variety of ATIS information sources. Because these devices will be integrated into IVIS as components, they are referred to in this paper as IVIS subsystems. Such a system, using modern digital technology, will tailor information both to the driver`s needs and to the driving environment. A variety of other efforts, both in the Us and abroad, either have been completed or are nearing completion, and the results of these efforts will be incorporated into this present system. IVIS must perform three high level functions (Tufano, et al, 1997). It must (1) interact with (ATIS) subsystems, (2) management information, and (3) interact with the driver. To safely develop and evaluate such a device, a platform must be devised which permits testing in an off-road setting

Groundwater vulnerability of principal aquifers of the Campania region (southern Italy)

The assessment of groundwater vulnerability is an important aspect of territorial planning aimed at the management and protection of groundwater quality. This topic is particularly relevant for the Campania region (southern Italy) due to the abundance of groundwater resources and the strong dependence on them of current economic, social and environmental settings. The region is characterized by complex geological, structural and hydrogeological frameworks which make challenging and innovative the assessment of groundwater vulnerability with SINTACS, a parametric method officially recognized by the Italian environmental agencies. In order to apply results obtained to current regional regulations, groundwater vulnerability was estimated for the 80 principal aquifers, hosting respective groundwater bodies, as recognized by the application of the Directive 2000/60/EC. Among principal results, the alluvial and limestone (karst) aquifers, which are the most productive of the region, show the highest groundwater vulnerability, even with spatially variable conditions depending on local hydrogeological features

In-vehicle information system functions

This paper describes the functional requirement for an In-Vehicle Information System (IVIS), which will manage and display all driving-related information from many sources. There are numerous information systems currently being fielded or developed (e.g., routing and navigation, collision avoidance). However, without a logical integration of all of the possible on-board information, there is a potential for overwhelming the driver. The system described in this paper will filter and prioritize information across all sources, and present it to the driver in a timely manner, within a unified interface. To do this, IVIS will perform three general functions: (1) interact with other, on-board information subsystems and the vehicle; (2) manage the information by filtering, prioritizing, and integrating it; and (3) interact with the driver, both in terms of displaying information to the driver and allowing the driver to input requests, goals and preferences. The functional requirements described in this paper have either been derived from these three high-level functions or are directly mandated by the overriding requirements for modularity and flexibility. IVIS will have to be able to accommodate different types of information subsystems, of varying level of sophistication. The system will also have to meet the diverse needs of different types of drivers (private, commercial, transit), who may have very different levels of expertise in using information systems

A comparison of methods for assessing groundwater vulnerability in karst aquifers: the case study of Terminio Mt. aquifer (Southern Italy)

The assessment of groundwater vulnerability to pollution is becoming even more important all over the world due to the increase of impacts of human activities on groundwater resources and the related risks to the human health, economics, and the environment. Owing to the variability of methods known for estimating groundwater vulnerability, basically depending on hydrogeological parameters considered and the scale of analysis, the comparison of results of different methods appears straightforward for identifying the best approach in a given hydrogeological condition and reference scale. In such a view, this work attempts to assess the groundwater vulnerability of the Terminio Mt. karst aquifer, by applying four different groundwater vulnerability methods, index-based, and comparing results in order to identify the best performing one in karst environments. The study aquifer, located in the Picentini Mts Regional Park (Campania region, southern Italy) represents a strategic drinking water resource since Roman times and hosts massive groundwater resources which outflow mainly from tapped basal and subordinately perched springs. The peculiar characters of the study karst aquifer, which favour direct infiltration and groundwater recharge processes, as well as the occurrence of industrial, agricultural and grazing activities, make it very vulnerable to groundwater pollution, thus requiring a proper and careful territorial management. Beside the most frequently and generally used methods for assessing groundwater vulnerability, such as the DRASTIC and SINTACS, also DAC and COP methods specifically designed for karst aquifers were applied and mutually compared. Results of SINTACS, DRASTIC and DAC methods show groundwater vulnerability maps of the Terminio Mt. karst aquifer as chiefly characterized by two classes of intrinsic groundwater vulnerability, varying between the medium and high degrees. Furthermore, high and extremely high values of groundwater vulnerability were found in areas controlled by the shallow depth of the water-table. Instead, the COP method resulted as the most effective in identifying the endorheic areas and the related karst morphologies as very high groundwater vulnerability zones, therefore the most suitable in capturing specific hydrogeological features of karst areas that control groundwater pollution and vulnerability. Results obtained will support decision tools aimed at the land use planning and protection of karst aquifers from pollution in karst areas