Channel, dune and sand sheet architectures of strait-adjacent deltas, Rifian Corridor, Morocco

THE ROLE OF SAND THICKNESS AND PALEOTOPOGRAPHY ON PHREATOPHYTE AND NON-PHREATOPHYTE SPECIES DISTRIBUTION ALONG A NORTH - SOUTH TRANSECT OF THE SOUTH TEXAS SAND SHEET

10.1130/abs/2019sc-327358 ◽

2019 ◽

Author(s):

Christopher Joaquín Munoz ◽

◽

Juan L. Gonzalez ◽

Chu-Lin Cheng

Keyword(s):

Species Distribution ◽

South Texas ◽

The South ◽

Sand Sheet

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Landward fining from multiple sources in a sand sheet deposited by the 1929 Grand Banks tsunami, Newfoundland

Sedimentary Geology ◽

10.1016/j.sedgeo.2007.01.012 ◽

2007 ◽

Vol 200 (3-4) ◽

pp. 336-346 ◽

Cited By ~ 84

Author(s):

Andrew L. Moore ◽

Brian G. McAdoo ◽

Alan Ruffman

Keyword(s):

Multiple Sources ◽

Grand Banks ◽

Sand Sheet

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Geochronology of the Bolson sand sheet, New Mexico and Texas, and its archaeological significance

Geological Society of America Bulletin ◽

10.1130/b30173.1 ◽

2010 ◽

Vol 122 (11-12) ◽

pp. 1950-1967 ◽

Cited By ~ 13

Author(s):

S. A. Hall ◽

M. R. Miller ◽

R. J. Goble

Keyword(s):

New Mexico ◽

Sand Sheet

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Cold-Climate Aeolian Sand-Sheet Formation in North-Western Europe (c. 14–12.4 ka); a Response to Permafrost Degradation and Increased Aridity

Permafrost and Periglacial Processes ◽

10.1002/(sici)1099-1530(199709)8:3<295::aid-ppp256>3.0.co;2-0 ◽

1997 ◽

Vol 8 (3) ◽

pp. 295-311 ◽

Cited By ~ 87

Author(s):

C. Kasse

Keyword(s):

Western Europe ◽

Cold Climate ◽

Permafrost Degradation ◽

Aeolian Sand ◽

Sand Sheet ◽

North Western

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Contextualized sedimentation rates for large floods along the lower Mississippi River: the importance of flood duration

10.5194/egusphere-egu21-15498 ◽

2021 ◽

Author(s):

Paul Hudson ◽

Franklin Heitmuller ◽

Samuel Muñoz ◽

Jansen Costello

Keyword(s):

Suspended Sediment ◽

Sedimentation Rate ◽

Field Data ◽

Flood Events ◽

Sediment Thickness ◽

Flood Duration ◽

Sedimentary Deposits ◽

Sand Sheet ◽

Overbank Sedimentation ◽

Sampling Procedures

Flood sedimentary deposits vary due to upper basin and lower basin controls. In this study we focus on overbank sediment thickness, which over longer periods drives changes to riparian aquatic habitat and floodplain construction. The study setting is a ~25 km long segment of the lower Mississippi alluvial valley, between Natchez, MS and Red River Landing, LA. We report new field data for overbank sedimentation generated by compound flooding over 2018 and 2019 hydrologic years, and compare with sedimentation data from prior large flood events. Overbank conditions in 2018 and 2019 persisted for 286 days (at Natchez, MS). During the 2019 hydrologic year the Mississippi was overbank for a record duration of 216 days, resulting in a much greater duration of overbank sedimentation than the 2011 (53 days) and 1973 (90 days) flood events.The thickness of overbank deposits are reported for 48 field sites across a range of depositional environments typical of large lowland meandering river floodplains. Flood deposits were sampled in October 2019 using conventional field sampling procedures, including sedimentation traps (artificial grass mats installed in October 2017) and recognition of recent sediment deposited atop buried organic layers. The thickness of each reported sample is an average of three measurements obtained at each field site.The average thickness of flood deposit samples over 2018-2019 hydrologic years is 71 mm, with variability according to distance from channel and floodplain depositional environment. Maximum sedimentation was associated with crevasse (750 mm) and sand sheet (1,430 mm) deposition along the crest of natural levees. Sedimentation thickness decreases within ~250 m of the channel, but remains high at a distance of ~3.5 km (30 mm). Beyond the range of sand sheet deposition, overbank deposition is likely influenced by variability in floodplain hydrology and geomorphology across natural levee (181 mm), meander scroll (30 mm), old channel (77 mm), and backswamp (108 mm) environments. High backswamp sedimentation at the study site is likely influenced by historic hydraulic engineering for flood control, which has altered local sedimentation patterns.The 2018-2019 sedimentation data are contextualized by comparison with field data from the record 2011 magnitude flood (peak Q of 65,978 m3/s at Vicksburg, MS, USGS 0728900) and the historic 1973 flood (55,558 m3/s). &#160;Average sediment thickness for the 2011 and 1973 overbank deposits was 42 mm (n=49) and 230 mm (n=31), respectively. The 2018-2019 daily sedimentation rate (0.25 mm/day) is much less than 2011 (0.75 mm/day). Thus, the much thicker sedimentary deposits for the 2018-2019 events suggests the greater importance of flood duration &#8211; rather than flood magnitude &#8211; to overall floodplain processes and alluvial fill chronologies along lowland rivers. The much lower flood sedimentation rate for 2018-2019 in comparison with 1973 (2.49 mm/day) may reveal the persistent decline in Mississippi suspended sediment loads since the early 1950s. Study results are further contextualized by considering corresponding event-based discharge &#8211; suspended sediment dynamics, sediment province, as well as flood hydroclimatology.

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