102,109 research outputs found
Sistemazioni Idraulico Forestali: Indirizzi per gli interventi
No full textMonografia che presenta le linee guida metodologiche, tecniche e scientifiche per la progettazione sostenibile degli interventi si sistemazione idraulico forestale (SIF). Vengono trattati i seguenti temi: ruolo delle SIF, interventi sul reticolo montano, foreste di protezione, rapporti tra SIF e Ingegneria Naturalistica
Sull'utilizzo delle talee nelle sistemazioni di versante
No full textNel presente lavoro viene affrontato il tema della valutazione del contributo delle talee alla sistemazione dei versanti. In particolare, viene presentato uno schema di calcolo per valutare il fattore di sicurezza di un pendio in presenza di talee, basato sull’analisi all’equilibrio limite delle forze agenti sul complesso terreno-talea. Lo schema proposto tiene conto sia delle caratteristiche specifiche del versante (pendenza, parametri geotecnici, grado di saturazione), sia delle caratteristiche della specie vegetale utilizzata (numero di germogli radicali, resistenza delle radici, frequenza del diametro), sia dei parametri progettuali (lunghezza delle talee, angolo di posa, spaziatura longitudinale e trasversale). Lo schema sviluppato è stato applicato utilizzando le caratteristiche biotecniche di talee di Salice rosso (Salix purpurea L.) misurate nell’ambito di una sperimentazione eseguita presso il vivaio dell’Azienda Regionale delle Foreste della Regione Lombardia situato a Borno (BS). I risultati ottenuti dall’applicazione mostrano un buon accordo con i valori dedotti da Schuppener (1999) mediante prove dirette di sfilamento di piantine radicate. I risultati ottenuti mostrano altresì un consistente effetto di rinforzo esercitato dalle talee, che si dimostra determinante per mantenere il fattore di sicurezza oltre l’unità
A simple stochastic model of point source solute transport in rivers based on gauging station data with implications for sampling requirements
No full textA simple point-source water quality model was constructed to explore hypothetical scenarios of linear alkylbenzene sulphonate (LAS) load variability, chemical degradation kinetics, river discharge and river velocities within the context of planned water quality monitoring in the river Lambro, northern Italy. LAS is an anionic surfactant and a commonly used ingredient of household detergents. Input loads were derived from flow and concentration measurements at sewage treatment works (STW). River travel times are approximated using hydraulic geometry concepts based on existing records of stage, discharge and velocity measurements. The model proved to be especially useful in predicting the impact of overflows from an undersized STW near the top of the catchment on diurnal variations in water quality downstream. Probability density functions (pdf's) of LAS concentrations for a number of points on the river were approximated by running the model stochastically (using a Monte Carlo procedure) over independent frequency distributions of discharge, temperature and input load. The predicted concentration pdf's were then used to estimate the number of random grab and 24h composite samples, which would be required in order to estimate mean concentrations with confidence. This is especially important in situations where the analysis is expensive and the sample budget is limited. The model results showed that grab sampling was not a viable strategy in the Lambro largely due to the very strong diurnal variability in concentrations induced by the STW overflow. This conclusion was corroborated by field data. Copyright (C) 1999 Elsevier Science Ltd
Best practices in post-flood surveys: The study case of Pioverna torrent
No full textFloods cause fatalities and considerable economic damage to infrastructures and settlements, besides impacting fluvial-geomorphic landforms. The increase in the frequency and magnitude of flood events has contributed to inevitably gaining public concern over the flood risk and awareness of the necessity to improve forecasting and monitoring streamflows. In this context, an efficient and systematic procedure of post-event surveys that documents the impacts of a flood event over the territory is often missing. Flood areas delimitation, erosion-sediment variation, and riparian vegetation change are often neglected. The present study shows the field- and desk-based post-flood surveys conducted after an extreme event occurred on June 12th, 2019, along the Pioverna torrent in Valsassina (North Italy). The post-flood surveys consist in collecting meteorological data and time-series satellite images to detect the land cover change (identifying areas covered by water, sediments, and vegetation), and in planning, a few weeks later, an unmanned aerial vehicle (UAV)-based survey to observe the riverbed and streambank change and the modifications in vegetation patterns through high-resolution derived-topographic data. The results show accurate maps of a ground classification from satellite-based elaboration and high-resolution digital elevation models from UAV-based surveys that can support restoration activities and the design of effective countermeasures. This practical application is appropriate and suitable as a river management strategy regarding timing, resources, and economic costs. Thus, standardising the procedure could be essential for creating a historical database, useful to improve specific guidelines and postemergency management strategies
Identification and Analysis of Natural Channel Networks from Digital Elevation Models, Earth Surface Processes and Landforms
No full textVegetation analysis and estimation of forest reconstitution time in protected areas of Val Camonica (Southern Alps) where a commercial mixture of seeds was sown. eco.mont (Journal on Protected Mountain Areas Research)|eco.mont Vol. 9 No. 1 9 1|
No full textThis study examined the vegetation composition of five sites of the Southern Alps (Val Camonica, Italy) where a commercial seed mixture had been used to restore vegetation at the end of soil stabilization works. The five sites are located in two protected areas of the Alps (the Parco dell’Adamello and the Riserva Naturale delle Valli di Sant’Antonio), and represent a chronosequence of year of sowing. We used a set of floristic-vegetational indices (index of maturity, indices of the life forms, and Landolt ecological indices) to analyse the characteristics of the vegetation of the five sites and to find a model that would allow an estimation of forest reconstitution time. From data analysis we found that, in areas which have had more recovery time, the sown heliophilous species and the ruderal herbaceous species decrease, while shrubs, trees and typical species of mature forests increase. The values of the index of maturity also increase according to time elapsed after sowing; the relationship that, in the present case, links the index of maturity to time was expressed formulaically. This model provided an estimation of the time required for the reconstitution of the forest community which, in this case, was about twenty years. This research, prompted by a request from the managing institutions of the two protected areas for a botanical investigation into the outcome of using the seed mixture, provided information that will enable them to assess whether to use the mixture in future environmental restoration work in the same areas
Dimensionamento delle gradonate e loro effetto sulla stabilità dei versanti
No full textNell’ambito dell’ingegneria naturalistica le gradonate, realizzate con talee o piantine radicate, costituiscono interventi maggiormente diffusi nella sistemazione di frane superficiali o nella realizzazione di scarpate ad elevata pendenza come nel caso della realizzazione di strade agro-silvo-pastorali. L’effetto di queste opere è duplice, nell’immediato viene fornito un rinforzo ad opera delle talee o dei fusti delle piantine, successivamente si ha un ulteriore rinforzo dovuto alla presenza delle radici avventizie. Nonostante la grande diffusione di queste opere, gli schemi di calcolo in grado di quantificarne l’effetto di rinforzo e di guidare la scelta dei parametri progettuali sono ancora scarsi. Nel presente lavoro viene illustrata una metodologia di calcolo basata sul principio dell’equilibrio limite del pendio indefinito al fine di valutare il fattore di sicurezza di versanti rinforzati con talee. Nel caso specifico viene considerato il salice rosso (Salix purpurea L.) per il quale sono state condotte sperimentazioni per valutare i parametri che regolano la resistenza allo sfilamento delle tale ed il rinforzo esercitato dalle radici avventizie
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