1,721,014 research outputs found
Tutela ambientale e riassetto idraulico del territorio
No full textINDICE:
La degradazione naturale: geodinamica esogena. Agenti climatici ed erosione: erosione idrica, erosione eolica, movimenti gravitativi.
Degradazione meteorica: alterazione chimica e fisica e biotica delle rocce. Azione delle acque di deflusso superficiale sui versanti: erosione, trasporto e sedimentazione. Forme dei processi erosivi sui versanti: erosione diffusa, incanalata, calanchi. Fattori influenti e modelli per la stima dell’erosione.
La circolazione delle acque superficiali: idrografia e geomorfologia fluviale: bilancio idrologico,bacino idrografico, imbrifero e idrogeologico, pattern di drenaggio. Bacini torrentizi e fluviali: caratteri e parti
Erosione, trasporto e sedimentazione ad opera delle acque inalveate. Livello di base dell’erosione, profilo d’equilibrio.
Portata solida fluviale: trasporto in sospensione, trasporto di fondo e trasporto in soluzione. Portata, idrogramma di piena, coefficiente di deflusso, tempo di corrivazione.
Stabilità dei versanti: movimenti di massa, morfologia delle frane, classificazione. Causa delle frane, effetti sul territorio.
Criteri per la sistemazioni dei torrenti e dei versanti
Interventi per la difesa del suolo e la regimazione delle acque, tecniche d’ingegneria naturalistica
Geologia applicata e idrologia
No full textIndex - Action of meteorological agents on slope dynamics.
Geotechnics characterisation of rocks: porosity, grain-size, Atterberg limits, water and rocks.
Elements of hydrology and hydrogeology
Measurement of climate data, distribution and cartographic representation of precipitation. Subsurface water, water table and artesian aquifers. Action of meteorological agents and influencing factors.Rainwater erosion, morphology of erosion processes on slopes: surface erosion, deep erosion.
Wind erosion.
Slope instability, mass movement: causes, effects on the territory, morphology of landslides, classification.
Action of watercourses. Fluvial sedimentation, erosion and transport. Basal level of erosion, equilibrium profile.
Hydrographic, catchment and hydrogeological basin. Hydrographic network, hydrographic patterns.
Torrential and fluvial basins: characters and parts, meanders, fluvial terraces, river bed.Morphometry of hydrographic basins (hierarchical order, drainage density.).Elements of fluvial hydrology
River flow rate, fluvial regime, basin water balance, drainage coefficient. Modes of transport: suspension, traction and solution
Study of precipitation and liquid and solid flow rates, for the design of fluvial engineering works: climate possibility distributions, Gumbel method, rainfall extremes, return periods.
Hydraulic-forestry engineering techniques in torrent basins, nature engineering works.
Elements of aerophotogrammetry
Stereoscopic interpretation of aerial images and photo interpretation for the identification of forms of slope instability and erosion, and for hydrography.
Topic-specific cartography: production of topic-specific maps, guiding principles. Reading and interpretation of topic-specific maps (slope, lithologic and slope-distribution stability, etc.)
Suspended sediment concentration for three Apenine monitored basins: particle size distribution and physical parameters
No full textSuspended sediment transport for different Apenine monitored streams: relationship with hydrological and physical parameters.
No full textEstimate of suspended sediment concentration: comparison of different techniques used in a monitoring programme.
No full textEvaluation of erosion mountain basins by the suspended sediment monitoring programme in three Apennines rivers.
No full textAnalysis of suspended sediment yield and particle size distribution from three Apennine Torrents
No full textEstimating the impact of land use change on catchment fluxes: the Gaiana case study.
No full textAbstract:
Agricultural policies try to manage land use change wisely. However such changes do not affect local economies only, but also runoff and sediment yield patterns. In order to estimate the impact of land use change on water and sediment fluxes, the erosion model KINEROS2 was used on the Gaiana basin (8.7 Km2), nearby Bologna, as its outlet was gauged with a monitoring station. The model was calibrated with measured discharge and sediment data and simulations were run using different land use scenarios, which were produced according to changes likely to occur because of “Set Aside” policies.
Introduction and aims
Agricultural policies do not affect local economies only, but other factors as well, like runoff and sediment yield patterns in natural catchments. It is well known that soil erosion control can be achieved by intervening on agricultural patterns. When farming is replaced by grasslands, bush lands and woods both surface and channelled erosion processes are mitigated. As a consequence, relevant environmental benefit might be achieved if farms were addressed to non-agricultural land covers. Positive results have been gained in many cases via the application of set-aside policies (Reg. CEE n. 1094/88): fields remain uncultivated for five years, either kept lying fallow or reafforested but not used for agricultural purposes. Present study aimed at assessing what effects set-aside policies might have when applied to agricultural areas set on hillsides with unsuitable slope conditions and occurring erosion phenomena, by means of simulations created by the event oriented, physically based hydrologic model KINEROS2
Hydrological and SSY monitoring programme to estimate soil erosion in experimental basins at different scales in the Reno catchment
No full textIn the year 1997 a hydrologic, turbidimetric and geochemical monitoring programme was set up concerning the river Reno and some of its main tributaries. Thus according to the interest in sediment dynamics, gauging stations were built at the mouth of the Reno river (4139 Km2), at the outlet of the mountain basin of three of its tributaries, the Sillaro (139 Km2), the Lavino (83 Km2) and the Savena (124 Km2), and at the outlet of the minor Gaiana torrent (8.7 Km2). Each monitoring station was equipped with an ultrasonic flow meter, interfaced to an automatic pumped sampler
The analysis performed on river samples are: suspended sediment concentration through gravimetric analysis, particle size distribution by the pipette method, turbidity with a laboratory turbidimeter and free settleable solids in Imhoff cone The turbidimetric method showed some shortcomings like the inaccuracy experienced both with highly turbid samples and with the presence of coarse particles. The free settleable solids in Imhoff cones resulted to be a simple, fast and low-cost method to estimate S.S.C.; moreover it has been possible to use it for the all the samples, with less restriction according to sample characteristics than the turbidimetric technique.
The fluctuation of suspended sediment concentration appears to be connected to the water flow measured during the sampling. This hypothesis was confirmed by considering the data file of the suspended sediment concentration and the water flow, simultaneously measured. Thanks to the data and the analysis results presented we might state that
• significant storm events are clustered during spring and autumn in all the three basins, as expected by their typical Apennines climatic regime
• absolute maximum values in S.S.C. occur during summer season, probably because of heavy convective storms and the low vegetation cover for draught and agricultural practices. S.S.C. in average is higher in autumn, probably because of the high frequency of storm events in this season.
• mean S.S.C. and maximum S.S.C. correlated well with “rainfall-based” variables, specifically with the maximum rainfall intensity (Imax), the Erosivity Index (E.I.) and the total rainfall height (Ptot)
• mean and maximum solid load best correlated with E.I. and rainfall maximum intensity
The results seem to indicate as hillsides as main sources of material to the monitored torrents. Cultivated lands on these basins are quite modest, therefore gully formations, pastures and degraded meadows have to be considered as main sources of sediment. The geologic and geomorphologic characteristics of the basins confirm this hypothesis, along with the numerous hydraulic arrengements confirming the highly unstable character of these lands.
Nevertheless, the database produced within the context of the Reno basin monitoring programme is now reaching quite a good amount of data, this making it possible to undertake research activities in the field of hydrological numerical modelling and their capabilities. There is the strong belief that mathematical models along with their strengths and weak points should be widely tested, especially since they might be applied outside than research contexts and situations.
For the time being, the event oriented, physically based model KINEROS2 is being used and tested. Rainfall-runoff events recorded at the outlet of the mountain catchment (8.7 Km2) of the Gaiana torrent were used in order to calibrate the model, so that KINEROS2 characteristics and capabilities could be assessed
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