The morphological analysis of an alpine stream can represent a real challenge, given the geomorphological and hydrological complexity of the area. However it is of fundamental importance as the various topographical characteristics of the main stream and its tributaries provide useful information in order to evaluate phenomena such as runoff, CO2 emissions and sediment transport. The survey sites, examined in this thesis work, belong to the Valfredda basin located in the north-east of Italy and include some areas of the main stream and some of its tributaries. The research was conduced under the scope of the "ERC DyNET" (Dynamical river network: climatic controls and biogeochemical function) project. As a survey methodology, drone photogrammetry was used with the support of a ground GPS antenna in "Cinematic Stop & Go" mode with RTK correction. The images captured by the drone and the GPS data were processed within Agisoft Metashape in order to obtain a 3D model of the various areas and finally DEM, orthophotos were extracted using the same software and then processed in QGIS for the purpose of an optimal morphological understanding of the area. The methodologies used made it possible to obtain high-precision models containing morphological data such as slopes and elevations. This confirmed the robustness of the chosen methodology. Through the use of a Matlab algorithm it was possible to identify the steps in the stream beds and their spatial and geometric configuration; making it possible to observe an inverse proportionality between the mean step distance and the slope of the reach under examination. The procedure for determining the steps presents issues linked to the DEM, interference and morphological complexity of mountain torrents, but with appropriate arrangements made during the survey phase the result can be improved. The results obtained in this thesis refer to the year of the measurement campaigns, thus providing the opportunity to lay the foundations for future comparative studies on the morphology of the area.
L'analisi morfologica di un torrente alpino può rappresentare una vera sfida, data la complessità geomorfologica e idrologica dell'area. Tuttavia è di fondamentale importanza in quanto le varie caratteristiche topografiche del torrente principale e dei suoi affluenti forniscono informazioni utili per valutare fenomeni quali il deflusso, le emissioni di CO2 e il trasporto di sedimenti. I siti di indagine, esaminati in questo lavoro di tesi, appartengono al bacino del Valfredda, situato nel nord-est dell'Italia, e comprendono alcune aree del torrente principale e alcuni dei suoi affluenti. La ricerca è stata condotta nell'ambito del progetto "ERC DyNET" (Dynamical river network: climatic controls and biogeochemical function). Come metodologia di indagine è stata utilizzata la fotogrammetria da drone con il supporto di un'antenna GPS a terra in modalità "Cinematica Stop & Go" con correzione RTK. Le immagini acquisite dal drone e i dati GPS sono stati elaborati all'interno di Agisoft Metashape al fine di ottenere un modello 3D delle varie aree e infine sono stati estratti DEM, ortofoto con lo stesso software e poi elaborati in QGIS ai fini di una comprensione morfologica ottimale dell'area. Le metodologie utilizzate hanno permesso di ottenere modelli di alta precisione contenenti dati morfologici quali pendenze e quote. Ciò ha confermato la robustezza della metodologia scelta. Attraverso l'uso di un algoritmo Matlab è stato possibile identificare i gradini nel letto del torrente e la loro configurazione spaziale e geometrica; ciò ha permesso di osservare una proporzionalità inversa tra la distanza media dei gradini e la pendenza del tratto in esame. La procedura di determinazione dei gradini presenta problematiche legate al DEM, all'interferenza e alla complessità morfologica dei torrenti di montagna, ma con opportuni accorgimenti in fase di rilievo il risultato può essere migliorato. I risultati ottenuti in questa tesi si riferiscono all'anno delle campagne di misura, fornendo così l'opportunità di porre le basi per futuri studi comparativi sulla morfologia dell'area.
Analisi morfologica di un torrente alpino mediante l’uso di fotogrammetria da drone
BURBELLO, ANDREA
2021/2022
Abstract
The morphological analysis of an alpine stream can represent a real challenge, given the geomorphological and hydrological complexity of the area. However it is of fundamental importance as the various topographical characteristics of the main stream and its tributaries provide useful information in order to evaluate phenomena such as runoff, CO2 emissions and sediment transport. The survey sites, examined in this thesis work, belong to the Valfredda basin located in the north-east of Italy and include some areas of the main stream and some of its tributaries. The research was conduced under the scope of the "ERC DyNET" (Dynamical river network: climatic controls and biogeochemical function) project. As a survey methodology, drone photogrammetry was used with the support of a ground GPS antenna in "Cinematic Stop & Go" mode with RTK correction. The images captured by the drone and the GPS data were processed within Agisoft Metashape in order to obtain a 3D model of the various areas and finally DEM, orthophotos were extracted using the same software and then processed in QGIS for the purpose of an optimal morphological understanding of the area. The methodologies used made it possible to obtain high-precision models containing morphological data such as slopes and elevations. This confirmed the robustness of the chosen methodology. Through the use of a Matlab algorithm it was possible to identify the steps in the stream beds and their spatial and geometric configuration; making it possible to observe an inverse proportionality between the mean step distance and the slope of the reach under examination. The procedure for determining the steps presents issues linked to the DEM, interference and morphological complexity of mountain torrents, but with appropriate arrangements made during the survey phase the result can be improved. The results obtained in this thesis refer to the year of the measurement campaigns, thus providing the opportunity to lay the foundations for future comparative studies on the morphology of the area.File | Dimensione | Formato | |
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https://hdl.handle.net/20.500.12608/35541