1,721,073 research outputs found
A Method for Estimating the Peak Discharge Through the Records of mean Daily Discharges
No full textSi propone un metodo di analisi regionale per derivare la distribuzione di probabilità dei massimi annuali della portata al colmo da quella dei massimi annuali della portata media giornaliera
Osservazioni preliminari sulla dinamica morfologica dell'Arno nel tratto compreso tra Figline e Rignano
No full textCarta geomorfologica dell'area circostante l'abitato di Monte San Martino (Prov. di Macerata, medio bacino del Tenna).
No full textMonitoraggio e vulnerabilità idrogeologica delle risorse idriche sotterranee lungo il tunnel ferroviario appenninico alta velocità Bologna-Firenze
No full textviene illustrata l’attività di monitoraggio ambientale delle risorse idriche sotterranee (sorgenti, pozzi) per la valutazione delle eventuali anomalie arrecate al regime idrogeologico naturale dai lavori di scavo del tunnel ferroviario Alta Velocità fra Bologna e Firenze. Oltre ad un resoconto dell’attività fin qui svolta in 4 anni di prospezioni sul campo (1995-1999), vengono prese in esame, in particolare, alcune problematiche riscontrate nel tratto appenninico Toscano (alto bacino del Santerno, massiccio calcareo-marnoso di Monte Morello)
Un esempio di cartografia geomorfologica applicativa su base morfometrica per lo studio dei centri abitati instabili.
No full textGeo-hydrological Hazards, "Anatomy of an Orogen"
No full textGeo-hydrological hazards result from natural earth processes, related to the interaction between meteorological phenomena, the geological environment and man's activities, which can potentially cause loss of the exposed elements at risk. Data on the social and economic impact of geo-hydrological hazards in Italy occurring in the 1945-1990 period are discussed and the causes defined
Vulnerability assessment and risk mitigation: the case of Vulcano Island, Italy
No full textThe paper reports on a comprehensive vulnerability analysis based on a research work developed within the EC ENSURE Project (7FP) dealing with the assessment of different volcanic phenomena and induced mass-movements on Vulcano Island (S Italy) as a key tool for proactive efforts for multi-risk mitigation. The work is mainly focused on tephra sedimentation and lahar hazards and related physical, systemic and mitigation capacities
Dinamica morfologica recente dell’alveo del Fiume Arno
No full textIl volume descrive la dinamica morfologica recente dell'alveo del F. Arno. Numerose sezioni trasversali ed alcuni profili longitudinali dell'alveo, rilevati in anni differente nell'ultimo secolo e mezzo sono analizzati attraverso una specifica parametrizzazioen delle loro caratteristiche geomorfiche
The fluvial dynamics of the Arno River - 4. Map of the morphological-sedimentary and human characteristics of the Arno river bed and alluvial plain (Table 7 “MONTEVARCHI”).
No full textThe results of a survey of the morphological-sedimentary and human characteristics of the Arno River bed and plain of the upper Valdarno, including the confluence of the Ambra Creek and St. Giovanni Valdarno, are reported by means of a thematic map at 1:10,000 scale. In this stretch, the river flows in an almost straight line with alternate side bars, within a plain having an average width of 1 to 2 kilometers. The present planimetric form of the river bed derives from the number of training works and canalisations undertaken in this section from the beginning of the 17th century, and which have caused, as the most visible consequence on the morphology of the course, a noticeable reduction in the width of the bankfull channel (from 300-500 metres to the present 150 metres), and the disappearance of interlacement, which was very frequent before 1700. During recent decades, the morphological and sedimentary characteristics of the river have been strongly influenced by intense gravel extraction, and by the construction of the artificial lakes of Levane and La Penna immediately upstream. These factors have certainly influenced the sedimentary equilibrium of the river, causing or encouraging erosive phenomena: the river is affected by a notable lowering of its bed, while the planimetric activity is very limited since there is hardly an erosion of the banks. The sedimentary bodies have a low mobility and a tendency to remain "suspended" with respect to the present level of the low waters. The sedimentary characteristics of the river bed are also considered in this paper and are graphically documented: the river is gravelly, with the average diameter of the material being between -3 and -6 phi. The bank protection works grant the river bed an elevated planimetric stability. On the other hand, the lowering process of the bed has made consolidation work on existing bridges necessary. The construction of a dam by E.N.E.L. has contributed to an altimetric fixation of the river bed bottom. The main aquifers present in the alluvial plain are distributed in correspondance to the coarse flood material, especially along the ancient river bed. Usually, the groundwater is affected by a field of motion which converges towards the river and which seems to be fed by them, except for local and temporary inversions of the groundwater-river relationships, especially in those areas with a greater water withdrawal. As far as the risk of flooding is concerned, this paper is limited to reporting the situation after the flood of November 4, 1966 (the maximum flow was reached in Montevarchi: 2,580 m^3/sec). On this occasion however, the tributaries caused the most damage. The flooded area of 1966 can only give us an indication of the areas which are more at risk of flooding should the same conditions repeat themselves, even if one must consider that some of the tributaries have undergone works of reinforcement, bridling and raising of the embankments. Only a few points of localised flooding have remained more or less unchanged, for example around bridges
Modeling of the Guagua Pichincha volcano (Ecuador) lahars
No full textLahars, here defined as debris flows of volcanic origin, are rapid mass movements that pose a serious threat to cities located in the vicinity of many volcanoes. Quito, capital city of Ecuador and placed at the foot of the Pichincha volcano complex, is exposed to serious inundation hazard as part of the city is built on numerous deposits of large lahars that have occurred in the last 10,000 years. The objective of this paper is to model the potential lahars of the Pichincha volcano to predict inundation areas within the city of Quito. For this purpose two models that apply different approaches were utilized and their results were compared. The programs used were LAHARZ, a semi-empirical model conceived by the United States Geological Survey (USGS), and FLO-2D, a hydraulic model distributed by FLO Software Inc. LAHARZ is designed as a rapid, objective and reproducible automated method for mapping areas of potential lahar inundation (Proc. First Int. Conf. on Debris Flow Hazards Mitigation, San Francisco, USA, ASCE, 1998, p. 176). FLO-2D is a two-dimensional flood routing model for simulating overland flow on complex surfaces such as floodplains, alluvial fans or urbanized areas (FLO-2D Users manual, version 99.2). Both models run within geographical information systems (GIS). Fieldwork was focused on collecting all available information involved in lahar modeling. A total of 49 channel cross-sections were measured along the two main streams and stratigraphic investigations were carried out on the fans to estimate the volume of previous events. A global positioning system was utilized to determine the coordinates of each cross-section. Further data collection concerned topography, rainfall characteristics and ashfall thicknesses. All fieldwork was carried out in cooperation with the Instituto Geofisico of the Escuela Politecnica Nacional. Modeling in a GIS environment greatly aided the exportation of results for the creation of thematic maps and facilitated model comparison. Evaluation of the models was performed by comparing simulation results against each other and against the geometry of existing lahar deposits. © 2002 Elsevier Science Ltd. All rights reserved
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