lnteraetions of River Diseharge with Sea lee in Proximity of Aretie Deltas: A Review
Summary: The most important effect an ice cover has on river discharge is forcing water to spread horizontally over very wide sheets of smooth seasonal ice before draining vertically at flow vortices (strudel) into the sea. These stru-del excavate craters as deep as 6 m on the seafloor, thereby rewo...
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| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.474.6872 http://epic.awi.de/28491/1/Polarforsch2000_13.pdf |
| Summary: | Summary: The most important effect an ice cover has on river discharge is forcing water to spread horizontally over very wide sheets of smooth seasonal ice before draining vertically at flow vortices (strudel) into the sea. These stru-del excavate craters as deep as 6 m on the seafloor, thereby reworking deltaic strata. Most drainage occurs at and seaward of the 2-m isobath through floating fast ice, and results in supercooling anel underwater ice formation. This frazil evidently scavenges and disperses scour-excavation products from strudel, as such sediments are not found in surrounding levees. Kilometer-wide sheets of bottom-fast ice land ward of the 2-m isobath stay submcrgcd under flood waters for about one week, evidently by suction rather than,,ice bond-ing " with the bed. While the bottom-fast ice finally rises, strudel also form here, although most water probably is introduced into the widening gap between the sea bed and rising fast ice by horizontal intake frorn the sea. Flood-ing of vast regions of bottom-fast ice also occurs during winter storrn surges, when depth of water on the ice should correspond to the height of the storm surge ( ± Im). Water irnport- anel export under the ice as much as 2 m thick may cause the very wide 2-m ramps characteristic for arctic deltas. Deposition of alluvial sand on top of the fast ice off river mouths during spring peak river discharge is not weil documented, and may not occur at all. There is no evidence that any spring deposits of alluvial sand are exported from deltas by ice rafting. Anchor ice carrying sediment forrns on the beds of arctic rivers, but no sediment export by such ice has been observed. Zusammenfassung: Die wichtigste Rolle des Festeises an arktischen Fluss-mündungen ist, dass es zur Verteilung des Süßwassers über große Areale |
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