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| Titel |
Sedimentation monitoring including uncertainty analysis in complex floodplains: a case study in the Mekong Delta |
| VerfasserIn |
N. V. Manh, B. Merz, H. Apel |
| 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 ; 17, no. 8 ; Nr. 17, no. 8 (2013-08-01), S.3039-3057 |
| Datensatznummer |
250018952
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| Publikation (Nr.) |
 copernicus.org/hess-17-3039-2013.pdf |
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| Zusammenfassung |
| Quantity and quality of sediment deposition in complex floodplains are
affected by many processes that are typically highly spatially and temporally
variable and hard to quantify exactly. The main processes in this context are
suspended sediment transport dynamics in rivers, floodplain channel
interactions, and internal floodplain processes. In consequence, any point
measurement of sedimentation in floodplains contains a high degree of
uncertainty, both stemming from measurement errors and from the lack of
representativeness for a larger area. However, up to now, uncertainty
analyses have not been performed as part of publications on floodplain
sedimentation data. Therefore the present work illustrates a field sampling
strategy aiming at the monitoring of floodplain deposition and spatial
variability on a large scale and at the quantification of uncertainties
associated to sediment deposition data. The study was performed in the Mekong
Delta, being an example for a large and complex floodplain with a high degree
of anthropogenic disturbances. We present a procedure for the quantification
of the uncertainty associated to the data, based on the design of the
monitoring campaign, sampling procedures, and floodplain characteristics.
Sediment traps were distributed strategically over the floodplain in clusters
of three mat traps representing one monitoring point. The uncertainty
originating from collection of the traps from still ponding water is
quantified by lab experiments. The overall uncertainty of the deposition
samples and the associated nutrient content is quantified in a Monte Carlo
simulation and illustrated by uncertainty bounds. For the study area the
results show a very high variability of the annual floodplain deposition
(2.2–60 kg m−2) with uncertainty bounds ranging from −61 to
+129% relative to overall mean deposition of 11.4 kg m−2. No
correlations in the spatial distribution of sedimentation in the
floodplains could be found. This is caused by the highly complex
channel and dike system and the high number of hydraulic structures. Also, no
differences in deposition between floodplain compartments protected with high
and low dikes could be detected. However, it can be shown that within single
floodplain compartments the spatial deposition variability depends on the
dike levels and operation and location of hydraulic structures. |
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