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| Titel |
Distributed specific sediment yield estimations in Japan attributed to extreme-rainfall-induced slope failures under a changing climate |
| VerfasserIn |
K. Ono, T. Akimoto, L. N. Gunawardhana, S. Kazama, S. Kawagoe |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 15, no. 1 ; Nr. 15, no. 1 (2011-01-20), S.197-207 |
| Datensatznummer |
250012596
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| Publikation (Nr.) |
 copernicus.org/hess-15-197-2011.pdf |
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| Zusammenfassung |
The objective of this study was to estimate the potential sediment yield
distribution in Japan attributed to extreme-rainfall-induced slope failures
in the future. For this purpose, a regression relationship between the slope
failure probability and the subsequent sediment yield was developed by using
sediment yield observations from 59 dams throughout Japan. The slope failure
probability accounts for the effects of topography (as relief energy),
geology and hydro-climate variations (hydraulic gradient changes due to
extreme rainfall variations) and determines the potential slope failure
occurrence with a 1-km resolution. The applicability of the developed
relationship was then validated by comparing the simulated and observed
sediment yields in another 43 dams. To incorporate the effects of a changing
climate, extreme rainfall variations were estimated by using two climate
change scenarios (the MRI-RCM20 Ver.2 model A2 scenario and the MIROC A1B
scenario) for the future and by accounting for the slope failure probability
through the effect of extreme rainfall on the hydraulic gradient. Finally,
the developed slope failure hazard-sediment yield relationship was employed
to estimate the potential sediment yield distribution under a changing
climate in Japan.
Time series analyses of annual sediment yields covering 15–20 years in 59
dams reveal that extreme sedimentation events have a high probability of
occurring on average every 5–7 years. Therefore, the
extreme-rainfall-induced slope failure probability with a five-year return
period has a statistically robust relationship with specific sediment yield
observations (with r2 = 0.65). The verification demonstrated that the
model is effective for use in simulating specific sediment yields with
r2 = 0.74. The results of the GCM scenarios suggest that the sediment
yield issue will be critical in Japan in the future. When the spatially
averaged sediment yield for all of Japan is considered, both scenarios
produced an approximately 17–18% increase around the first half of the
21st century as compared to the present climate. For the second half of
the century, the MIROC and MRI-RCM20 scenarios predict increased sediment
yields of 22% and 14%, respectively, as compared to present climate
estimations. On a regional scale, both scenarios identified several common
areas prone to increased sediment yields in the future. Substantially higher
specific sediment yield changes (over 1000 m3/km2/year) were
estimated for the Hokuriku, Kinki and Shikoku regions. Out of 105 river
basins in Japan, 96 will have an increasing trend of sediment yield under a
changing climate, according to the predictions. Among them, five river
basins will experience an increase of more than 90% of the present
sediment yield in the future. This study is therefore expected to guide
decision-makers in identifying the basins that are prone to sedimentation
hazard under a changing climate in order to prepare and implement
appropriate mitigation measures to cope with the impacts. |
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