Field observations of the June 30, 2001 debris flow at Acquabona (Dolomites, Italy) |
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Authors: | Pia Rosella Tecca Rinaldo Genevois |
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Institution: | (1) Consiglio Nazionale delle Ricerche, IRPI, C.so Stati Uniti 4, 35127 Padova, Italy;(2) Dipartimento di Geologia, Università di Padova, Via Giotto 1, 35137 Padova, Italy |
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Abstract: | On June 30, 2001, a debris flow occurred in the Acquabona Creek, a small catchment of the Eastern Dolomites, Italy. This debris
flow originated shortly after an intense rainstorm, characterised by a peak intensity of 8.6 mm per 10 min; it transported
a total volume of 30,000 m3, consisting of poorly sorted gravely sand with boulders up to 3 m in diameter. The sediment erosion yield rate reached as
high as 20 m3/m. In order to verify the accuracy of the field measurements, the total volume of debris deposits have was calculated using
three different topographic measurement techniques: 3D laser scanning, terrestrial stereo-photogrammetry survey and total
topographic station survey. Data collected so far show that no debris flow has occurred at Acquabona with a rainfall intensity
lower than 4.6 mm per 10 min. Channel cross section measurements indicate that debris flow velocity ranges from 2.0 to 7.2 m/s
along the lower flow channel and peak discharge ranges between 22 and 300 m3/s. Field estimates of the rheological properties indicate a yield strength ranging from 2,088 to 5,313 Pa and Bingham viscosity
between 70 and 337 Pa · s. It is not still possible to identify a rainfall intensity and amount threshold for debris flow
triggering, but the data so far collected emphasise that debris flows do not occur with a rainfall intensity lower than 4.6 mm
per 10 min. |
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Keywords: | Debris flow Precipitation Physical properties Rheological properties Dolomites Italy |
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