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| Titel |
Subsidence of River Delta Systems and Enclosed Basins Caused by Multi-decadal to Millennial Scale Sediment and Ocean Loading |
| VerfasserIn |
Ronald G. Blom, Erik R. Ivins, Volker Klemann, Roy K. Dokka, Rowena Lohman, Eric J. Fielding |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250043624
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| Zusammenfassung |
| The causes of multi-decadal coastal subsidence that exceed the rate of 20th-21st Century
mean sea-level rise are numerous. A host of causal relationships between anthropogenic
activity and coastal erosion and subsidence are both compelling and well understood. A short
list of these processes should include: fluid extraction, reservoir compaction; fluid-induced
motion of shallow growth-faults; decomposition of organic sediments (left in the wake
of major water diversion projects) and sediment empoundment and/or diversion.
Non-anthropogenic post-glacial sediment loading-induced subsidence has also been
demonstrated to be a candidate mechanism that could dominate the GPS-mapped subsidence
in the Mississippi-Atchafalaya Rive Delta system (Ivins, Dokka and Blum, GRL, 34, L16303,
2007). More recent changes in sediment load can also have a substantial impact on the active
subsidence of the crust and mantle. These can be of both anthropogenic and natural origins.
Here we examine, in varying degrees of detail, the world’s major delta systems
wherein the necessary and sufficient conditions are met that allow sediment plus
water load to drive gravitationally-layered, hydrostatically pre-stressed viscoelastic
Earth model simulations far enough away from gravitational equilibrium that a
detectable geodetic signal in tide-gauges and GPS vertical position would be predicted.
Sediment-load-induced subsidence occurs over horizontal length scales, λ, comparable to
thickness of the lithosphere: λ -¥ 40-60 km and has amplitudes ranging from of 0.5 to 8
mm/yr (Ivins et al. GRL34, 2007; Syvitski Sustain. Sci., 3, 2008). The cases of the
pan-Arctic deltas, the Atchafalya –Mississippi River Delta system, the Yangzte River and
Yellow River Deltas of China, the Danube River Delta Plain, and the generally
complex postglacial water-sediment loading of the Black Sea and Caspian Sea. |
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