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| Titel |
Analysis of different water-sediment flow processes in a mountain torrent |
| VerfasserIn |
M. Arattano, L. Franzi |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 4, no. 5/6 ; Nr. 4, no. 5/6 (2004-11-30), S.783-791 |
| Datensatznummer |
250001396
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| Publikation (Nr.) |
 copernicus.org/nhess-4-783-2004.pdf |
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| Zusammenfassung |
| Sediment – water flows occurring in mountain torrents may show a variety of
regimes, ranging from water flows with transport of individual particles to
massive transport of debris, as it occurs in case of debris flows. Sometimes
it is possible, by means of accurate field investigations, to identify the
kind of processes that took place in a torrent after the occurrence of an
event. However this procedure cannot give indications regarding the
development of the process in time. In fact, because of the frequent
presence of different surges within the same event, the rheological
characteristics of an event can be detected only when some recorded
hydrographs or videos are available. For the same reason, since the
rheological behaviour of the flow changes according to the solid
concentration, the analysis of the materials deposited on the debris fan
cannot directly give any information on the particular types of flow that
took place: a possible alternation in time of different water sediment
surges with different concentrations may have occurred, during the same
event. The installation of ultrasonic gauges or videocameras along the
torrent might give more information on this issue. To this regard, the
analysis of a flow event which occurred in 2002 in the Moscardo torrent
watershed, instrumented for debris flow monitoring, has been undertaken,
studying the hydrographs recorded at two different ultrasonic gauges placed
at a known distance along the torrent. An empirical flow resistance law has
been applied analysing the values assumed by its parameters after
calibration. The application of this law actually spans from debris flow and
immature debris flow to bed load transport. Only field observations and
surveys, together with ultrasonic data, may allow to clearly discriminate
which type of flow really occurred. The analysis confirms that different
water sediment surges alternated in time while the mathematical simulation
of the flow compared with field observations revealed that the dynamic
behaviour of the flow was different from that of previous debris flow events
and might reflect, among the different types of possible rheological
behaviors, a dilatant-type behavior typical of stony debris flows. |
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