 |
| Titel |
Downstream patterns of bed material grain size in a large, lowland alluvial river subject to low sediment supply |
| VerfasserIn |
M. B. Singer |
| Konferenz |
EGU General Assembly 2009
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250022461
|
|
|
|
|
|
| Zusammenfassung |
| A new data set of bimodal subaqueous channel bed sediments was analyzed for longitudinal
patterns in grain size. It yielded two interesting observations: (1) separate fining trends in d50
exist for gravel and fines that overlap for ˜1 75 river kilometers, and (2) this overlap in fining
trends results in a protracted (nonabrupt) gravel to sand transition. These suggest bed
patchiness that is interpreted in the context of inherent grain size bimodality, localized
hydraulic sorting due to spatially heterogeneous (and low) sediment supply, and local
deviations in channel gradient. The data also show that tributaries have a minor
impact on main stem downstream fining due to basin shape and tectonic history. In
addition, subaqueous channel sediments were observed to be finer than nearby
sediments collected from exposed bars, which may indicate a narrow active zone of
transport where bars are disconnected from sediment movement. This research
has implications for bed material collection and theories of downstream fining. |
|
|
|
|
|
|