Maria Gabriella Forno

Landslide Susceptibility Zoning Using GIS Tools: An Application in the Germanasca Valley (NW Italy)

This book is one out of 8 IAEG XII Congress volumes, and deals with Landslide processes, including: field data and monitoring techniques, prediction and forecasting of landslide occurrence, regional landslide inventories and dating studies, modeling of slope instabilities and secondary hazards (e.g. impulse waves and landslide-induced tsunamis, landslide dam failures and breaching), hazard and risk assessment, earthquake and rainfall induced landslides, instabilities of volcanic edifices, remedial works and mitigation measures, development of innovative stabilization techniques and applicability to specific engineering geological conditions, use of geophysical techniques for landslide characterization and investigation of triggering mechanisms. Focuses is given to innovative techniques, well documented case studies in different environments, critical components of engineering geological and geotechnical investigations, hydrological and hydrogeological investigations, remote sensing and geophysical techniques, modeling of triggering, collapse, runout and landslide reactivation, geotechnical design and construction procedures in landslide zones, interaction of landslides with structures and infrastructures and possibility of domino effects. The Engineering Geology for Society and Territory volumes of the IAEG XII Congress held in Torino from September 15-19, 2014, analyze the dynamic role of engineering geology in our changing world and build on the four main themes of the congress: environment, processes, issues, and approaches.

Detailed geological mapping in mountain areas using an unmanned aerial vehicle: application to the Rodoretto Valley, NW Italian Alps

ABSTRACT We present a methodology to use a UAV (unmanned aerial vehicle) to perform photogrammetric surveys and detailed geological mapping in mountain areas. This work is specially related to the presented case study with the aim to realize geomorphological maps from UAVs, since they can house different types of sensors and acquire data more rapidly and cheaply than traditional geological surveys directly obtained with field observations. This work explains how UAVs can obtain digital terrain models, orthophotos and 3D models in order to create slope and aspect maps for geological purposes. By integrating data from UAVs with geological surveys made on the field, geological maps can be produced where many of the geological elements are presented. This paper presents the integration of geomatics and geological techniques. Starting from UAV slope map and orthophotos, a new geological map was created in a faster and more detailed way compared to traditional geological survey on the ground. The application of this method regards a sector of the Western Alps (NW Italy), formed by glaciers and deep-seated gravitational slope deformations.

GSTOP: a new tool for3D geomorphological survey and mapping

Abstract In geological mapping activities, geomatics can facilitate data collection during field survey and avoid practical problems related to the transposition of these data onto maps for GIS production. The Solid True Orthophoto (STOP) can reduce these difficulties using a dedicated instrument developed by the Authors called GSTOP. It can run on laptops or tablets, managing a direct connection with low cost navigation sensors in real time, to define its location and attitude. The user can produce a 3D solid image in order to compare the effective scene to record notes and to acquire evidence. GSTOP has been used to produce a geomorphological map of the Rodoretto Valley (Germanasca Valley, NW Italy), reconstructing its Quaternary evolution.

Preliminary results on temperature distribution in the Quaternary fluvial and outwash deposits of the Piedmont Po Plain (NW Italy): a statistical approach

We propose a statistical approach to the study of subsoil thermal data in order to find an equation able to describe the temperature distribution in the underground of the Piedmont plain sectors (NW Italy). The analytical model here proposed, can be used during the preliminary stage of investigation for the exploitation of subsoil by means of low enthalpy geothermal plants. The statistical analysis was performed using groundwater thermometric data from thermal logs collected in boreholes crossing the Quaternary fluvial deposits hosting a shallow aquifer.

The Ivrea Morainic Amphitheatre as a Well Preserved Record of the Quaternary Climate Variability (PROGEO-Piemonte Project, NW Italy)

In the Piedmont plain of NW Italy the Ivrea Morainic Amphitheatre (IMA) is a remarkable evidence of the Quaternary glaciations. It consists of a wide (505 km2) complex of lateral moraines (i.e. the Serra d’Ivrea), end moraines and kame terraces, encircling a 200 km2 wide flat internal depression above which a subglacially moulded rocky hills (the Colli d’Ivrea) elevates. The glacigenic succession ranges from the end of the Early Pleistocene (dated on palaeomagnetic basis) to the end of the Late Pleistocene (14C radiometric and 10Be exposure ages) (about 900–20 ky BP). The IMA has recently been parted into ten stratigraphical units, potentially correlable to the whole sequence of the main Quaternary glaciations recorded by the marine oxygen isotope stratigraphy. Natural (glacigenic deposits and forms) and archaeological (i.e. the Roman gold mines) features make the IMA a very interesting topic for a multidisciplinary research with educational, cultural and tourist purposes. Some recent and present activities for the land promoting are presented. A candidature to the UNESCO global geopark network is considered as a suitable and ambitious goal.

Aeolian and reworked loess in the Turin Hills (northwestern Italy)

Abstract The Upper Pleistocene aeolian loess of the Turin Hills is of interest because of its primary distribution and subsequent diffuse reworking, both of which were appreciably conditioned by the presence of the hills themselves. The deposition of loess was confined to a small area within which it displays a discontinuous distribution and a widely varying thickness. The loess has also been subjected to reworking by sheet flow on the steeper slopes and by channel flow in depressions. These two phenomena have been responsible for the considerable distribution of the reworked loess. These is therefore a marked contrast between the Turin deposit and most other loess units of the Po plain, which are thin, continuous and uniform over large areas, and have been subjected to only slight reworking as a result of their deposition on flat or only slightly undulating surfaces.

Thermal features and antropogenic warming of shallow aquifers in Piedmont region (NW Italy)

The study concerns part of the plain sector of Aosta Valley (NW Italy). The investigated area is located between the cities of Sarre-Gressan and Pollein-Saint Christophe and is characterized by the presence of hexavalent chromium in the main shallow unconfined aquifer. The pollution is probably related to the negative environmental effects induced by the industrial steel production that since 1915 is present over the area. Since 1990 the industrial area was subjected to a number of direct investigations aimed to assess the contamination intensity. A preliminary remediation activity has been developed in last decades but the contaminants have been still observed in the groundwater monitoring network. This study highlights the set-up of a groundwater conceptual and numerical model of the shallow aquifer aimed to better understand and analyze the transport dynamics of hexavalent chromium in the local aquifer. The simulation is performed using the specific finite element software Feflow for groundwater flow and mass transport modeling. The hydrogeological setting of this area is related to the different sedimentary glacial, lacustrine and fluvial processes which characterized the bottom of the Aosta valley during the Quaternary. The shallow 80m-width aquifer is constituted by sandy to gravelly deposits and presents rare silty lens while its bottom is characterized by a decametric lacustrine silty level. The main aims of the numerical model are to give a more unequivocal explanation of the origin of the contamination and to support the predictive analyses in order to design an efficient site remediation for soil and groundwater. This represents a fundamental task in order to preserve the safety of the public water uses supplied by the aquifer. The preliminary hypothesis about the source of contaminations are still uncertain and referred to different scenarios that have to be further investigated by comparing monitoring data and transient flow simulation conditions.

The use of temperature monitoring to define the groundwater flow paths

The study concerns part of the plain sector of Aosta Valley (NW Italy). The investigated area is located between the cities of Sarre-Gressan and Pollein-Saint Christophe and is characterized by the presence of hexavalent chromium in the main shallow unconfined aquifer. The pollution is probably related to the negative environmental effects induced by the industrial steel production that since 1915 is present over the area. Since 1990 the industrial area was subjected to a number of direct investigations aimed to assess the contamination intensity. A preliminary remediation activity has been developed in last decades but the contaminants have been still observed in the groundwater monitoring network. This study highlights the set-up of a groundwater conceptual and numerical model of the shallow aquifer aimed to better understand and analyze the transport dynamics of hexavalent chromium in the local aquifer. The simulation is performed using the specific finite element software Feflow for groundwater flow and mass transport modeling. The hydrogeological setting of this area is related to the different sedimentary glacial, lacustrine and fluvial processes which characterized the bottom of the Aosta valley during the Quaternary. The shallow 80m-width aquifer is constituted by sandy to gravelly deposits and presents rare silty lens while its bottom is characterized by a decametric lacustrine silty level. The main aims of the numerical model are to give a more unequivocal explanation of the origin of the contamination and to support the predictive analyses in order to design an efficient site remediation for soil and groundwater. This represents a fundamental task in order to preserve the safety of the public water uses supplied by the aquifer. The preliminary hypothesis about the source of contaminations are still uncertain and referred to different scenarios that have to be further investigated by comparing monitoring data and transient flow simulation conditions.

Distribution, Discharge, Geological and Physical–Chemical Features of the Springs in the Turin Province (Piedmont, NW Italy)

Numerous exploited springs (1571) have been investigated in the Turin Province. They have been mapped with a GIS on a new, specially drafted, geolithological map and statistically examined with regard to areal distribution, discharge, use and lithological composition of their catchment basin. One spring every 4 km2 occurs in this area. In detail, the spring density is greater in the mountains (1 spring every nearly 3 km2) than in the plains and in the hills (1 spring every 10–53 km2). These springs are well-distributed in the different altitude ranges, with two peaks at 800–1,100 m and at 140–300 m. They are mostly used for drinking water supply (65 %), irrigation (23.5 %), sanitary use (6 %) and, subordinately (5.5 %), industries, fish farms, production of electric energy and unknown use. The 54.7 % of the springs has discharge lower or equal to 1 l/s, while only the 2.7 % (43 springs) has discharge greater than 10 l/s. A 81 l/day drinking water supply each inhabitant is estimated per capita. The spring areal distribution into the different geolithological units and their discharge values (linked to the aquifer typology) are synthetized. A sample of 28 analyzed springs has bicarbonate to sulfate alkaline-earth facies. Their electric conductivity (100–400 μS/cm) is due to content of bicarbonates (mean value of 100 mg/l) and sulfates (mean value of 15 mg/l). In a single basin (Dora Riparia) the Total Hardness exceeds 25 French Degrees.

ERT geophysical surveys contributing to the reconstruction of the geological landscape in high mountain prehistorical archaeological sites (Plan di Modzon, Aosta Valley, Italy)

One of the few examples of high mountain prehistorical archaeological sites in northern Italy has been discovered within the so called Plan di Modzon area, at 2300 m a.s.l., in the Aosta Valley (Western Alps). This area shows interesting geological features and morphological evidence which have been recently linked to a wide Deep-Seated Gravitational Slope Deformation (DSGSD). A probable filled lake and the presence of buried landforms have been also hypno tized on the basis of geological observations, resulting in the need for new devoted surveys to confirm these hypotheses. A better and comprehensive understanding of the geological evolution of the area is indeed necessary to allow a precise reconstruction of the environments in which man has inhabited these territories. Combined Electric Resistivity Tomographies (ERT) and geological surveys have been therefore used to better define the occurrence and nature of morphological evidence along the western slope of the filled lake, in which one of the archaeological sites has been discovered and excavated. The outcomes of the integration of the two surveys is a more refined definition of the geological forms, in respect to the one previously assumed on the basis of surface surveys only. Indeed, ERT revealed buried zones with low resistivity associable to the presence of sliding surfaces and also showed the geometry and thickness of the sediments within the filled lake. Geological surveys also evidenced a DSGSD evolution in the area constrained to Lateglacial, because of the lack of particularly evident gravitative forms, i.e. remodeled by glacial abrasion.