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| Titel |
Correlation of Catchment Sedimentation and Landslides in Ta-Chia River Influenced by the 1999 Taiwan Chi-Chi Earthquake |
| VerfasserIn |
K.-J. Shou, L.-Y. Fei, J.-F. Lee, C.-Y. Wei, S.-T. Huang, Y.-C. Lin |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250022763
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| Zusammenfassung |
| It is generally accepted that the high frequency of landslide in Taiwan area is strongly
affected by its geomorphology and geology background. The geomaterials in Taiwan are
highly fractured due to the tectonic activity of collision of Phillipine sea plate and Eurosian
plate. The hilly Western Foothill is highly prone to landslides, especially during typhoon
season in the summer. The 1999 Chi-Chi earthquake (MW=7.6) resulted in tremendous
amount of landslides along the Ta-Chia River catchment of central Taiwan, with 1.5 million
m3 of earth driven from broken slopes (DGH, 2000). The impact of this earthquake not only
makes the geomaterial more fractured but also changes the river morphology in the Western
Foothill area.
The main purpose of this study is to investigate the correlation of catchment
sedimentation and landslides before and after the 1999 Chi-Chi earthquake. The Ta-Chia
River is a major river in central Taiwan, with 120km in length, 1200km2 in drainage area, and
elevation from 3600m to 360m. Beside the flow discharge and sediment discharge, the
hydropower facilities also play important roles in the sedimentation process, especially in the
catchment segment between Ku-Kuan Dam and Te-Chi Dam. This study divides the Ta-Chia
River catch to three segments, above Te-Chi Dam (I), Ku-Kuan Dam to Te-Chi Dam (II), and
below Ku-Kuan Dam down to Shih-Kang Dam (III). Analyses were performed for
each catch segment with discussions. The study comprises two major parts, i.e.,
catchment sedimentation and correlation with landslides. The former part includes field,
satellite image and DTM calculation results, and the later part includes analysis on the
correlation between the landslides and catchment sedimentation. Three typhoon
events, i.e., Herb (1996), Toroji (2001), and Mindulle(2004) are adopted for this
study.
Our findings indicate, comparing with typhoon Herb, 40% more sediments in
catchment segment II and 22% less sediments in catchment segment III were generated
by Toroji. The results also reveal sedimentation trend in segment I and incision
trend in segment III, however, there are still tremendous amount of sediments in
segment II. For the landslides in those three catchment segments, comparing with
typhoon Herb, 247% more reactivated landslides and 318% more new landslides
in segment I, 66 times more reactivated landslides and 43% more new landslides
in segment II, 209% more reactivated landslides and 59% less new landslides in
segment III were generated by Toroji. The results show strong correlation between the
catch sedimentation and landslides. However, the impacts of Chi-Chi earthquake
on different catchment segments are different. The landslides are more prone to
reactivation in the segment II, more prone to new generation in the segment I, and less
prone to new generation in the segment III. The Ta-Chia River catchment is an
appropriate area to test the seismic effect of the 1999 Chi-Chi earthquake, and this
case study could provide experiences of the sustained landslide investigation and
sediment estimation to regard as the reference of catchment management. It also
provides information to assess hazard risk and the future benefit of reconstruction. |
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