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| Titel |
Airborne LIDAR investigation of lithological controls on river behavior in a mountainous catchment following a major storm event |
| VerfasserIn |
M. Kasai, T. Kimura, T. Marutani |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250067461
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| Zusammenfassung |
| Airborne LiDAR is increasingly being used to investigate sediment dynamics in mountainous
catchments. By combining information on hillslope and river dynamics, our understanding of
the connectivity between geomorphic units both at micro and macroscopic scales is
expected to improve. This work reports a case study from three rivers in the upper Saru
River catchment (380 km2) in the Hidaka Mountain Range, Hokkaido, Japan. The
catchment is underlain by either soft Cretaceous marine sedimentary rocks or a solid
Cretaceous to Tertiary accretionary complex. Deep-seated landslides, the toes of which
often reach valley floors, are common in the former. The streams are also wider and
gentler than in the latter geology, through which v-shaped valleys have formed.
The catchment experienced aggradation throughout its river courses in a major
storm event in 2003. Airborne LiDAR data sets in 2006 and 2010 were employed to
examine landslide locations and changes in river form. In the soft rock areas, stream
courses were confined at landslide toes and tributary fans, the locations of which
affected the pattern of river behavior. While degradation was dominant over this
period, local aggradation occurred in places. In contrast, channel incision was intense
throughout the hard rock areas, where the entire bed degraded by 2-3 m. Data analysis
showed that the alignment of rock types clearly impacted on the residence times of
sediment delivered to the channel in 2003. Sediment released from these rivers was
accumulating downstream from their confluence point along a 15 km meandering
flood plain reach. Aggradation continued until the next confluence point. Field
observations showed that fresh materials continue to be supplied from adjoining deep
seated landslides and stored in the most upstream part of the catchment, indicating
that the next intense storm event could cause a repeat of this process in future. |
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