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A geotechnical monitoring campaign and a site investigation have been recently planned and undertaken aiming at the preservation and protection of the “Palazzone” Etruscan necropolis, an archaeological site dated back to Hellenistic period located 4 km from the city of Perugia, along the southeastern margin of the hill where the town is settled. The site includes some beautiful and monumental cavities, among them, the Volumni Hypogeum. The majority of the graves are underground cavities excavated in partially saturated alluvial soil deposits. Their inspection reveals the geological features and the depositional structures. The groundwater table is located about 35 m below the ground surface. Due to the difficulties of soil-sampling inside the ancient cavities, only limited portions of the material were retrieved for conventional laboratory tests, although not enough for a geotechnical characterization. On the other hand, XRD analyses and MIP tests were performed. The obtained results allowed to recognize the relevant contribution of soil suction to the stability conditions of the lateral walls and the ceiling of the cavities, which is complementary to the weak cementation characterizing the soil mass. This important information supports the conservation strategy of the monument, which has as its primary tool the monitoring of environmental conditions, aimed at maintaining the unsaturated conditions of the soil mass.

The design of engineering measures during emergency phases is crucial in mitigating the river flow impacts on landslide dams, avoiding dam breaks and related downstream flooding. Man-made hydraulic facilities represent a possible mitigation strategy for reducing the occurrence of dam breaching by diverting river inflow. Semi-empirical equations published in the literature may help define the landslide dam evolution and design the discharge to be diverted into the hydraulic works assuring the dam's stability. These approaches need to be carefully validated with case studies, an important step in evaluating the accuracy of predictive models. The work presents and discusses the pre- and post-seismic hydrologic conditions along the Nera River gorge focusing on the role of the pre-existing anthropic works in mitigating the impact of river discharge on the Sasso Pizzuto landslide dam triggered by the October 30, 2016 earthquake (Central Italy). Considering historical data, the upper part of the river catchment has experienced the highest discharge values during the landslide dam lifetime. The discriminant analysis approach of the hydro-geomorphometric characteristics supported the definition of the critical peak flow, avoiding the dam's instability. Thanks to an upstream hydropower bypass, about 80% of the river discharge increase have been diverted into an underground pipeline built in 1928 to feed the Preci hydroelectric plant (located a few kilometers downstream of the landslide dam). The discriminant analysis model, developed in the literature on other landslides worldwide, had a good performance in managing the upstream river discharge of Sasso Pizzuto dam, expanding its validity on other landslide dams.

The Bottaccione Gorge at Gubbio, in central Italy, has been an important source of information about Cretaceous and Paleogene Earth history. At the much younger end of the historical continuum, it is also important for understanding the early history of Gubbio itself, for which the only written, although somewhat ambiguous, evidence comes from the Tavole eugubine, the unique bronze tablets which are a kind of Rosetta Stone for the Umbrian language. The role of the Bottaccione Gorge is debated in the history of Gubbio. The road through the gorge, crossing the Monti di Gubbio, is an important element for explaining the location of the city. One of the first settlements (late Bronze Age) is recognized from archaeological evidence at the top of a morphological fault scarp on the slope of Monte Ingino. In the Iron Age, the city described in the Tavole eugubine developed, in which Okri (fortress), Tota (city), and three sacred gates are mentioned. The locations of Okri, Tota, and the gates are still under study. According to the most likely hypothesis, Tota would have developed in the plain, on the right bank of the Torrente Camignano, while the initial settlement would have been transformed into Okri, to which the sacred gates would belong. Another gate may have been placed at the entrance to the Bottaccione Gorge. When the Eugubini (the people of Gubbio) built the new, post-Roman Gubbio in the twelfth century, they still identified, as the most suitable place for a fortified city, the location above the scarp on the slope of Monte Ingino, and they built two new gates at its lateral ends. The city was likely equipped with a third gate that faced the Bottaccione Gorge. In the thirteenth century, the Bottaccione Aqueduct was built to bring water to the highest point of Gubbio. Thus, two waterways—one natural (Torrente Camignano) and the other artificial—still branch off from Bottaccione to reach Gubbio at two different points that determine the lowest and highest levels of the city.

On October 30, 2016, a seismic event and its aftershocks produced diffuse landslides along the SP 209 road in the Nera River Gorge (Central Italy). Due to the steep slopes and the outcropping of highly fractured and bedded limestone, several rockfalls were triggered, of which the main event occurred on the slope of Mount Sasso Pizzuto. The seismic shock acted on a rock wedge that, after an initial slide, developed into a rockfall. The debris accumulation blocked the SP 209 road and dammed the Nera River, forming a small lake. The river discharge was around 3.6 m3/s; the water overtopped the dam and flooded the road. By a preliminary topographic survey, we estimated that the debris accumulation covers an area of about 16,500 m2, while the volume is around 70,000 m3. The maximum volume occupied by the pre-existing talus mobilized by the rockfall is about 20% of the total volume. Besides blocking the road, the rockfall damaged a bridge severely, while, downstream of the dam, the water flow caused erosion of a road embankment. A rockfall protection gallery, a few hundred meters downstream of the dam, was damaged during the event. Other elastic nets and rigid barriers were not sufficient to protect the road from single-block rockfalls, with volumes around 1–2 m3. Considering the geological and geomorphological conditions, as well as the high seismicity and the socioeconomic importance of the area, a review of the entire rockfall protection systems is required to ensure protection of critical infrastructure and local communities.

Volumni Hypogeum is part of the Palazzone Etruscan necropolis, an archaeological site dated back to Hellenistic period (V sec B.C.). The Hypogeum is a large underground cavity excavated in a partially saturated alluvial soil deposit located in the outskirts of Perugia city. Stability conditions and safety requirements of the vault and the lateral walls are analysed based on the available field results. The physical properties of the material in which the Hypogeum was excavated, such as, natural water content, soil suction, relative humidity of the rooms, temperature, as well as the groundwater conditions undoubtedly influence the state of conservation of the site itself. The variations of these properties may significantly affect the mechanical behaviour of the soil-materials and, in turn, the stability conditions of the ceiling/walls. Moreover, the site is daily exposed to road/rail traffic-induced vibrations. If also considering seismic actions, this site is extremely vulnerable. A multi-scale approach methodology has been recently undertaken aiming at the preservation and protection of the soil/monument system. The present study focuses on a very recent investigation of the microstructural features of the in situ materials. Preliminary numerical analyses of the cave have been performed in order to investigate on the stability conditions.

This paper focuses on the problem of measuring stream power in a hydrographic network using the original definition provided by Bagnold in 1996. Recent digital elevation models have enabled the calculation of channel gradients and, consequently, stream power with a finer spatial resolution, and this has created promising and novel opportunities to investigate river geomorphological processes and forms. The work carried out in this study includes defining and implementing a methodological approach that could be automated within a geographic information system and that meets two requirements: (1) it uses a DEM as input data at a suitable resolution, (2) it estimates the stream power &Omega, as well as its variability along the considered stream, in the best possible way using available data. In particular, the methodological approach was implemented in a GIS environment (GRASS GIS) and applied to a sample basin to highlight the variability in &Omega, along the main stream and its most important tributaries. The sudden and more substantial variations in stream power were then related to the processes acting in the fluvial system. This approach made it possible to highlight how erosion, solid transport, and sedimentation phenomena occurring along the fluvial reaches are related to abrupt variations (increase/decrease) in the &ldquo, power&rdquo, available. The results of this study support the idea that the automated and standardized screening of stream power variability along a stream can be used as a preliminary diagnostic element to identify the most &ldquo, sensitive&rdquo, points of the stream on which to concentrate subsequent investigations (field checks to verify the causes), with the aim of mitigating risks due to the dynamics of the riverbed.

The paper describes the results of preliminary surveys and calculations carried out to study a debris flow occurred in the Rocchetta Valley (northeast Umbria, Italy) on November 11, 2013. This event is of particular interest because, although it can certainly be considered exceptional, is representative of conditions rather frequent in the Apennines. In this area the dynamics of ephemeral streams, present in narrow and steep valleys, was completely changed by human interventions and the risk conditions arising during extreme weather events are completely ignored. The collected data, result of bibliographic research, surveyed in the field and remotely sensed by a fixed-wing drone, indicate that the debris flow has developed about 1.8 km upstream of the town of Gualdo Tadino, at the confluence of a creek that originates from an important spring (Campitella) with the Feo Creek. The debris flow, after activating the old riverbed for about 1 km, settled at the end of the valley of the Feo Creek (in the outskirts of the town of Gualdo Tadino), about 6200 m3 of material, burying fully the establishment of the Rocchetta, well known in Italy for the production of mineral water.

This study examines plane failure analysis of rock slopes and discusses its effect on seismic actions in a non-dimensional form, incorporating external loads transferred by anchors and stability indicators such as the depth of tension cracks and the failure plane dip. The results of limit equilibrium analyses, in terms of attained level of safety, are summarized in stability charts which can be used for design and assessment. Following guidelines established by Eurocode EC7, the stability is assessed through the R/E ratio, i.e. the ratio of the resisting shear forces (R) acting on the sliding surface and those promoting sliding (E). The proposed stability charts can be applied to various common practical situations, in order to provide a preliminary - but quantitative - assessment of the rock slope stability. As an example of an application, the paper focuses on the stability of a rock mass located at the bottom of the southern slope of the “Sasso di Pale” mountain (Central Italy), at the outskirts of the village of Pale. As many other historical towns in Central Italy, due to their location close to rock masses, this site is particularly exposed to instability phenomena such as plane failure and rock wedge failure. The structural-geological survey allowed us to identify the main joint sets affecting the behavior of the rock mass and, accordingly, we examined the plane failure mechanism involving sliding along a single plane. Stability verifications in pseudostatic conditions have been performed by adopting the proposed charts, consistent with Eurocodes prescriptions.

The note deals with the problem of measurement and variability, along the fluvial reaches of a hydrographic network, of the stream power, according to the original definition provided by Bagnold (1966) “The available power supply, or time rate of energy supply, to unit lenght of a stream is clearly the time rate of liberation in kinetic form of the liquid’s potential energy as it descends the gravity slope S”. In formula: Ω = ρ g Q S where: Ω = stream power per unit of flow length (W/m) ρ g = density x gravity acceleration = specific weight of the fluid (kg/m3) Q = liquid discharge (m3/s) S = slope of the considered reach (m/m). Recent digital elevation models allow the calculation of channel gradient and consequently stream power with a finer spatial resolution, opening promising and novel opportunities to investigate river geomorphical processes and forms. The work carried out consisted in defining and implementing a methodological approach that could be automated within a geographic information system and that meets two requirements: 1) use input data that is easy to find as DEM at a low resolution; 2) estimate, in the best possible way and on the basis of the available data, the stream power and its variability along the considered stream. In particular, the methodological approach has been implemented in GIS environment (GRASS Gis, Qgis), and it has been applied to a sample basin, highlighting the variability of Ω along the streams of a higher order (in practice the main stream and its most important tributaries). The sudden and more substantial variations of stream power were then related to the processes acting in the fluvial system. This approach has made it possible to highlight how the erosion, solid transport and sedimentation phenomena occurring along the fluvial reaches (and the geomorphological and geologicalapplicative problems that these involve, especially in anthropized areas), are correlated precisely to abrupt variations (increase/decrease) of the ”power” available. Hence the idea that automated and standardized screening of stream power variability along a stream can be used as a preliminary diagnostic element to identify the most ”sensitive” points of the same, on which to concentrate subsequent investigations (field checks, to verify the causes), aimed at mitigating the risk due to the dynamics of the riverbed.

This work, based on the data of two earthworks recently completed on two sites near Lake Trasimeno (Central Italy), examines the consequences of the enforcement in Europe of the fall-cone test for the Liquid Limit (LLcone) instead of the Casagrande cup (LLcup). This new standard has been incorporated in the latest Italian soil classification (UNI 11531-1:2014), substituting the previous one (UNI 10006:2002). A set of 28 soil samples was analysed: the research shows that LLcone is always greater than LLcup. According to the old standard, all samples were suitable for the works planned but, according to the new one, 18 % of samples became unsuitable. This is in spite of the fact that there is nothing to show that the old classification was “unsafe.” The new standard (based on LLcone) restricts the choice of materials, so that not only will costs for earthworks increase in the future but, paradoxically, because of the new standard, thousands of kilometers of properly working old levees became suddenly “unsafe.” The results suggest that soil classification criteria for earthworks should be reconsidered in order to transform the conventional “index properties” to sound physical characteristics.

The note presents the results of a project, carried out by the Engineering Geology Group of Department of Physics and Geology of University of Perugia and funded by the Umbria Region, aimed at evaluating the hazard of occlusion of riverbeds by landslide (landslide dams) in the Upper Tiber Valley. The authors explain the used methodology that, starting from the data available in the catalogs of IFFI (Inventario dei Fenomeni Franosi in Italia, i.e. Italian Landslides Inventory) and PAI (Piano di Assetto Idrogeologico, i.e. Hydrogeological Assessment Plan), concerning the active and quiescent landslides, selects, through different steps (preliminary identification of landslides for which it is assumed the interference with riverbeds; photointerpretation; geomorphological survey; simulation of the total occlusion of riverbed; simulation of the collapse of the natural dam) the landslides for which is considered realistically possible the occlusion of riverbed due to a reactivation or persistence of the mass movement. The methodology also provides for a first evaluation of conditions of risk related to the complex phenomenon of interference between landslide and dynamics of riverbeds, for both areas located upstream of the dam, at risk of drowning due to the formation of the dam lake, both for those located downstream, where it is possible the transit of an abnormal flood wave, resulting from the eventual collapse of the natural dam and the rapid emptying of the lake.

This work reports the results of a geomorphological study on the River Paglia (Tiber basin, Central Italy), to analyse the historical evolution of the riverbed/floodplain system in its lower valley reaches, upstream the confluence of River Tiber. A morphological–sedimentological approach has been used, starting with an historical analysis and a survey of the forms and sediments in the riverbed/alluvial plain system, in order to reconstruct the current evolutionary trend and to identify the causes and processes leading to changes in natural trends. This approach is not in contrast to the hydrologic–hydraulic one, normally applied in engineering fields, but it is integrated with it in a complementary and parallel manner, in order to achieve the complete knowledge of the river system, result of an investigation multidisciplinary, aimed to define its physical state. Historical data (cartographic documents, digital terrain models—DTM, topographic surveys, aerial photographs, etc.) indicate clear-cut narrowing and deepening of the active channel, manifested after the Second World War and due to the considerable changes which affected the entire fluvial system (from the recovery of land for agriculture near the river, to sediments taken from its bed over the past few decades). The result is a state of great disequilibrium, which is shown in the passage from a braided morphology, observed in the 1950s, to a single channel with low sinuosity (wandering type). This type of morphology is certainly more unstable: in fact, the narrowing and deepening of fluvial sections provide a better hydraulic efficiency for the upstream, so the peak discharge does not overflow. Such peak discharge arrives downstream, next to the confluence with the Tiber River, not laminated, causing serious flooding effects. An increased vulnerability is observed in the last reach, in the areas pertaining to the river, where most of the industrial-economic activities are concentrated and where transportation infrastructures of nationwide importance (Italy’s most important motorway, the A1, and the Rome–Florence–Milan high-speed rail links) are located. The evolution of the Paglia (which is not substantially different from that of many streams in Italy and in general throughout Europe) is affected by severe anthropic constraints and intense exploitation of resources, which have produced a state of disequilibrium approaching irreversibility in an already vulnerable system. Finally, some suggestions for the correct management of the river system are pointed out, with the aim of mitigating the flood risk in the lower Paglia valley.

Image processing and classification techniques are widely used for land use definition. They can also provide interesting applications in fluvial geomorphology, for outlining morpho-sedimentary features (bars, channels, banks and floodplain) at various temporal stages, in order to monitor the evolution of river systems. Frequent monitoring is especially important for streams, in terms of flood risk in urban areas. This study shows how techniques of supervised analysis can be applied to river systems, also under particular conditions, like after flood events (when large portions of riverbed and alluvial plain are covered with mud). The procedure starts from the classical photogrammetric techniques, based on multispectral classification, and goes on with post processing operations of pixel aggregation and shadow treatment. The classification also uses the elevation information provided by Digital Surface Model produced by photogrammetry. This paper introduces a new technique of remote sensing in fluvial areas that allows for both the identification and classification of the fluvial features in a post flooding condition. Application of the procedure over time permits the evolution of the fluvial dynamics to be monitored in an accurate and inexpensive way, particularly for flood event conditions which lead to major changes in the dynamics of riverbeds.

Large landslides, triggered by earthquakes or heavy rainfall, often obstruct the river’s flow to form landslide dams, causing upstream inundations, and downstream flooding. In Italy, landslide dams are rather widespread along in Alps and Apennines: although the identification of past events is a complex task, some hundreds of landslide dams are identified in the literature. In order to assess the formation and evolution of landslide dams, several studies suggested the employment of geomorphological indexes. In this framework, the knowledge of site-specific time-space evolution can be useful in the understanding of the landslide dams phenomena. The present work focuses on a landslide dam that occurred in January 1973, which totally dammed the Bonamico River Valley (Southern Italy): the lake reached an area of about 175,000 m2, a volume of about 3.6 × 106 m3 and a maximum depth of 40 m. During 1973–2008, the lake surface gradually decreased and nowadays it is completely extinct by filling. By using satellite and aerial images, the paper discusses the evolution of the lake surface and the causes of the lake extinction. The use of a climate index (i.e., standardized precipitation index at different time scale) indicates that in recent decades the alternance of drought and heavy rainfall periods affected the inflow/outflow dynamics, the filling of lake due to the solid transport of the Bonamico River, and the failure of the landslide dam.

This work involves the implementation of a tool for evaluating Sediment Delivery Ratio (SDR) in a river basin, through GRASS GIS software. The definition of a spatially distributed value of SDR is a very important task as the sediment routing can affect solid transport in stream channels, water quality degradation, and frequency increase of natural disasters such as debris flows and mudflows. For such reason the SDR evaluation, coupled with GIS approach, has been extensively used in scientific literature. Geographic information systems provide a fundamental support for a better prediction of the SDR, since it can consider the space variability of factors influencing the sediment routing processes. Actually a specific GIS module to estimate the spatial variability of SDR does not exist. We implemented a GRASS GIS module (in python language) called r.sdr where the sediment delivery ratio is evaluated by GIS procedure by using several SDR equations available in literature. We applied the tool to the Feo Creek watershed, located in the Apennines area of northeastern Umbria (Italy).

The Italian cultural heritage is one of the most noticeable in the world; an important part of it is subjected to natural hazard and risk conditions. Religious buildings, due to their location on impervious sites are particularly exposed to landslides. In this paper we study the hermitage of Cerbaiolo (Tuscany, central Italy). The hermitage, founded in the 8th century as a Benedictine monastery is now a Franciscan Women Institute seat. The buildings are on the edges of a limestone plate overlapped to a clayey formation. Falls, toppling and slides are present along the limits of the plate due to the geomechanics properties of the rock and to the contrast between the two lithological complexes. In order to identify the main joint sets affecting the rock mass a structural-geological survey was carried out and four sets are identified. The rock plate was classified according to Bieniawski, Barton and Geological Strength Index approaches. The outcomes confirm the predisposing factors to mass movements, corresponding to the intensity and characteristics of fracturing of the rock mass. With regard to the slope stability analysis, a failure mechanism involving sliding along a single plane (plane failure) was assumed on the first approximation. The analyses take into account the presence of tension cracks as an indicator factor for the instability phenomenon. The results of stability analyses, performed in static and seismic conditions, indicate a widespread instability condition. The dip slope direction, the properties and type of discontinuities and the local variation of composition influence the hazard assessment.

The extreme versatility in different research fields of GRASS GIS is well known. A tool for the vertical sorting of sediments in river dynamics analysis is illustrated in this work.In particular, a GRASS GIS python module has been written which implements a forecasting sorting model by Blom&Parker (2006) to analyze river bed composition’s evolution in depth in terms of grainsize.The module takes a DEM and information relative to the bed load transport composition as input. It works in two different and consecutive phases: the first one uses the GRASS capabilities in analyzing geometrical features of the river bed along a chosen river reach, the second phase is the "numerical" one and implements the forecasting model itself, then executes statistical analyses and draws graphs, by the means of matplotlib library.Moreover, a specific procedure for the import of a laser scanner cloud of points is implemented, in case the raster DEM map is not available.At the moment, the module has been applied using flumes data from Saint Anthony Falls Laboratory (Minneapolis, MN) and some first results have been obtained, but the "testing" phase on other flume’s data is still in progress. Moreover the module has been written for GRASS 65 on a Ubuntu Linux machine, even if the debugging of a GRASS 64, Windowsversion, is also in progress.The final aim of this work is the application of the model on natural rivers, but there are still some drawbacks. First of all the need of a high resolution DEM in input, secondly the number and type of data in input (for example the bed load composition in volume fraction per each size considered) which is not easily obtainable, so the best solution is represented by testing the model on a well instrumented river reach to export in future the forecasting method to un-instrumented reaches.

A GIS Based method has been applied for the determination of the reduction in fluvial sediment transport, induced by small agricultural reservoirs. The method involves the Revised Universal Soil Loss Equation (RUSLE) for the estimation of the soil erosion (gross soil erosion) and the concept of sediment delivery ratio to route surface erosion from each cells to the catchment outlet. The SDR is often used coupled with RUSLE in order to reduce the over estimation of soil erosion provided by the RUSLE method itself. The process of sediment delivery from grid cells to the catchment outlet is represented by the topographical index derived from Digital Elevation Model (DEM). This procedure has been applied in the Upper Tiberian Valley (Tuscany-Umbria boundary, central Italy) in order to evaluate the pitfall effect of numerous small reservoirs present in this area.

The analysis of the flood hazard related to the areas downstream of landslide dams is one of the most interesting aspects of studying the formation and the failure of natural dams. The BREACH code [14], simulating the collapse of earthen dams, both man-made and naturally formed by a landslide, was chosen in order to analyse the case of the Valderchia landslide (central Italy). The bed-load transport formula used in BREACH (Meyer-Peter and Muller, modified by Smart [27]) is based on flume experiments with well-sorted sediments. Such a methodology probably makes this equation not very suitable for describing the sediment transport peculiar to a landslide body presenting a very poor material sorting. The Schoklitsch [26] formula was implemented into the programme as an alternative to the Smart equation. However, because the landslide deposits may often have a strongly bimodal grain–size frequency curve, the percentile D 50 (the typical granulometric parameter requested by bed-load sediment transport formulas) can sometimes correspond to one of the grain-size classes which are really present to a lesser degree. To consider this phenomenon, the BREACH programme (version 7/88-1) was implemented with a new procedure that calculates two granulometric curves, one for each mode of the original distribution, and evaluates transport of the landslide material separately. Results of the analysis show that the model is very sensitive to the bed-load equation and that the procedure implemented to consider the eventual bimodal distribution of the dam material simulates the armouring phenomenon (which can stop the erosion of the dam during the overtopping phase).

The paper presents the first results of a work aimed to develop automatic procedures, and/or semi-automatic, for the morphological and sedimentary analysis of riverbeds (made through multispectral aerial photographs) and to define the morphological changes (plano-altimetric) of the river, by comparison with previous surveys. The methodology has been applied to an area of study that includes the lower valley of River Paglia (a tributary on right of the River Tiber, in central Italy) where a flood, occurred in November 2012, has produced important morphological changes of the riverbed-floodplain system.

A landslide dam is a natural phenomenon in which the movement of a large quantity of material down the slopes dams a river. This paper presents a case of a dammed river where the natural lake has remained stable. The type and volume of the material are the main elements controlling such phenomena. A higher quality, digital elevation model was obtained with the use of a geostatistic approach, which couples an auxiliary map with the elevation data. A comparison between the DEM from before the event and after the event enabled the volume involved to be estimated more precisely and the main landslide features, such as the crown, the depletion zone and the accumulation zone, to be identified. The study enabled a method to be developed, which uses geostatistic interpolation techniques and auxiliary maps to achieve a better definition of the digital terrain model and, therefore, a more accurate assessment of mobilised volumes during the event, when topographic data are lacking.

The study of the Montebestia landslide (Umbria, Central Italy) is related to the general analysis of the types and causes of landslides which frequently involve the continental plio-pleistocenic sediments (gravels, sands, silts and clay) of the fluvial-lacustrine facies of the “Ancient Tiberian Lake Basin” (“Villafranchiano” Auctorum). The geological structure of the area is characterised by the presence of apenninic master faults and by antiapenninic joints and faults influencing the evolution of the landscape and the hydrographic network. The landslide is located in the Upper Tiberian Valley, next to Montone (in the province of Perugia). The stratigraphic sequence involved by the movement comprehends: silts (from clayey silts to sandy silts) with thin layers of gravels and sands; upper gravels and sands, bringing up the series. The dip of the clastic complex is towards SW, with an angle of inclination near to the slope inclination. The morphological evolution of the area was reconstructed by ancient cartographic documents and by aerial photos related to several flies (from 1954 to 1991). It shows that the lithological, structural and stratigraphic features were able to guide type, location, geometry and evolution of the mass movement. The results of the monitoring carried out by an inclinometer (to measure deep displacements), a GPS network (to measure surface movements) and piezometers (to control the relationships with groundwater) show a differentiated evolution, according to the type of mass movements recognisable in this area: multiple surface movements situated at a shallow depth and very slow movements (which are nonetheless constant over time) located at a major depth along a slide surface, which guided the various evolutive states. So this landslide, that can be classified as “complex landslide”, according to UNESCO (WP/WLI, 1993a; 1993b) owing to the described features, represents a significant example of the gravitational phenomena occurring in the clastic plio - pleistocenic sediments of the tuscan-umbrian “Villafranchiano” Auctorum, in Central Italy.

This paper provides a new statistical test to evaluate the threshold of validity for the Mean Stream Drop analysis. In the case of a constant area threshold, the method aims to provide a unique threshold value to extract the drainage network through a statistical test more efficient than those widely used. The proposal starts from the assumption that a minimum threshold value exists suitable for drainage network extraction. Then, the method proceeds with Horton–Strahler ordering of the network and statistically analysing the network geometry. This procedure is repeated for all the threshold values in the set under investigation, using a statistical permutation test, called APTDTM (Adjusted Permutation Test based on the Difference between Trimmed Means). Statistical significance is evaluated by p-values adjusted to account for multiple comparisons. As a final result of the statistical analysis, the right threshold value for the specific basin is identified. Classical procedures are based on a set of two sample t-tests. However, this method relies on the assumptions of normality and homogeneity of variance, which are unlikely to hold in practice. The APTDTM test presented here provides accurate p-values even when the sampling distribution is not close to normal, or there is heteroskedasticity in the data.

Target of this paper is to draw the relationship between environmental factors and some impacts due to human activity, in order to outline environmental quality restoring strategies for water bodies, which include among result indicators also biological parameters expected for Italian regulation and European directives. Morphologic equilibrium and correct knowledge of processes regulating fluvial dynamic, as basic factor of ecosystem functionality condition, are highlighted. Statistic evaluation processes of water quality data and implementation and validation of mathematical models are described.

The Bastardo Basin is one of the classics Apenninic intermontane basins of central Italy. They are en-closed tectonic basins (graben and semigraben) with high anthropization, but with high vulnerability, too (seismic, hydrogeological and geomorphological). The paper concerns some aspects about slope instability in the Bastardo Basin as part of a wider research, which aims to actually define the characteristics of the liability to landslides of the Apenninic intermontane basins. In particular lithological, stratigraphical and hydrogeological conditions are analysed under which a landslide near village of Barattano has developed. This mass movement, at different times, produced partial or total occlusion of the torrent Puglia. Here geognostic investigations together with laboratory tests and subsequent monitoring of landslide area were carried out. A back analysis, based on limit equilibrium solutions for the factor of safety of the slope, provided the residual strenght properties of the soil mass along the sliding surface. The landslide of Barattano is representative of a very frequent situation (in terms of type, factors and causes of the movement, possible development of the movement) not only within Bastardo Basin, but in general within Apenninic intermontane basins, too. The study of landslide and the design of appropriate remedial measures are of great importance in terms of prevention and mitigation of geologic-hydraulic risk in Apenninic intermontane basins.

Riassunto Il contributo fornisce qualche breve spunto di riflessione sulle relazioni fra Tempo e Cartografia. Nella fattispecie, sono presentati due esempi nei quali il tempo è stato utilizzato per il corretto posizionamento di un elemento su una carta. Il primo è un caso storico molto conosciuto, cioè la determinazione della longitudine in mare; il secondo, il Global Positioning System (GPS) è più recente: la tecnologia si sviluppa e si diffonde nell'ultimo decennio del secolo scorso ma l'idea era nata con la guerra fredda fra USA e URSS, dopo il lancio dello Sputnik, il primo satellite artificiale russo.