Efficient retention of mud drives land building on the Mississippi Delta plain
Many of the world's deltas – home to major population centers – are rapidly degrading due to reduced sediment supply, making these systems less resilient to increasing rates of relative sea-level rise. The Mississippi Delta faces some of the highest rates of wetland loss in the world. As a r...
| Main Authors: | , , , , |
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| פורמט: | Article |
| שפה: | English |
| יצא לאור: |
Copernicus Publications
2017-07-01
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| סדרה: | Earth Surface Dynamics |
| גישה מקוונת: | https://www.earth-surf-dynam.net/5/387/2017/esurf-5-387-2017.pdf |
| סיכום: | Many of the world's deltas – home to major population centers – are rapidly
degrading due to reduced sediment supply, making these systems less resilient
to increasing rates of relative sea-level rise. The Mississippi Delta faces
some of the highest rates of wetland loss in the world. As a result,
multibillion dollar plans for coastal restoration by means of river
diversions are currently nearing implementation. River diversions aim to
bring sediment back to the presently sediment-starved delta plain. Within
this context, sediment retention efficiency (SRE) is a critical parameter
because it dictates the effectiveness of river diversions. Several recent
studies have focused on land building along the open coast, showing SREs
ranging from 5 to 30 %. Here we measure the SRE of a large relict
crevasse splay in an inland, vegetated setting that serves as an appropriate
model for river diversions. By comparing the mass fraction of sand in the
splay deposit to the estimated sand fraction that entered it during its life
cycle, we find that this mud-dominated sediment body has an SRE of ≥ 75 %, i.e., dramatically higher than its counterparts on the open
coast. Our results show that transport pathways for mud are critical for
delta evolution and that SRE is highly variable across a delta. We conclude
that sediment diversions located in settings that are currently still
vegetated are likely to be the most effective in mitigating land loss and
providing long-term sustainability. |
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| ISSN: | 2196-6311 2196-632X |