| Autor: |
Futoshi Nakamura, Shun-ichi Kikuchi |
| Rok vydání: |
1996 |
| Předmět: |
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| Zdroj: |
Geomorphology. 16:139-145 |
| ISSN: |
0169-555X |
| DOI: |
10.1016/0169-555x(95)00139-v |
| Popis: |
Floodplain areas are primary storage sites for river sediment. In the Saru River, ages of floodplain surfaces were examined by tree ring analysis, and vertical and horizontal configurations of floodplain deposits were measured by field and aerial-photo surveying. A flood in 1992 provided a good opportunity to examine depositional and erosional processes of floodplain sediment before and after the flood. Predominant disturbances were observed in the unconstrained, wide reaches where floodplains develop. This event indicated that eroded areas of floodplain deposits in each age class linearly increased with sediment volume and that the proportion of the total area eroded decreased exponentially with increase in the age of sediment. We constructed basic equations expressing continuity of age distribution in order to analyze river sedimentation in a time series according to the results of the 1992 flood. The floodplain disturbance rates determined by this analysis showed similar temporal changes with sediment transport rates monitored at the Iwachishi Reservoir. A sharp increase in sediment discharge was seen after 1962 associated with the historical maximum rainfall in the temporal analysis of floodplain sediment. The time series approach presented here is useful for evaluating the speed of sediment waves and the cumulative impact of sedimentation in a river basin. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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