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Sediment dynamics in the lowermost Mississippi River

Sediment dynamics in the lowermost Mississippi River,10.1016/S0013-7952(96)00026-9,Engineering Geology,Joann Mossa

Sediment dynamics in the lowermost Mississippi River   (Citations: 72)
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There is much to be gained from investigating sediment dynamics in the lower Mississippi system, the largest river in terms of discharge and sediment load in North America. Such work can improve conceptual knowledge concerning downstream changes at the lower end of large river systems and can be applied to manage sediment diversions for wetland restoration in south Louisiana. Suspended sediment dynamics in the lowermost Mississippi River system in Louisiana are characterized using three approaches: (1) temporal changes in discharge-suspended sediment relationships showing interannual variations and the effects of floods over short timescales; (2) empirical relationships between discharge and suspended sediment variables at various locations; and (3) downstream changes in discharge-suspended sediment relationships. Interpretation of this data set is enhanced with other secondary data regarding processes, morphology, and bed materials.Upstream, near Old River, LA, empirical relationships show nonlinearity, particularly in fine sediments, with decreased concentrations at highest discharges. During high discharge years, suspended sediment concentration peaks precede discharge crests by 40–85 days. The lead generally decreases with decreasing discharge maxima so that in low discharge years sediment peaks and discharge crests closely coincide in time. Downstream, near Belle Chasse, LA, fine bottom materials are resuspended and the timing of sediment peaks and discharge crests is coincident, regardless of flow magnitude. Conceptually, results suggest caution when generalizing about the relative timing of the sediment wave and flood wave and their downstream progression. These phenomena are influenced by local bed material and hydraulic conditions, and depend on the causative factors of sediment peaks. From an applied perspective, diversions should be managed differently depending upon where they are constructed along the river and upon the magnitude of the annual maximum flow. During high discharge years, when concerns for navigation and water supply are minimal, flow should be diverted on the rising limb upstream, near Old River, and during the discharge crest downstream near New Orleans.
Journal: Engineering Geology - ENG GEOL , vol. 45, no. 1, pp. 457-479, 1996
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    • ...Approximately 28.5% of the Mississippi River delta plain has been lost since 1956 (Barras et al., 2008), most likely from the lack of seasonal inputs of nutrients and sediments from the Mississippi River, which formed the delta over the past 6000‐7000 years but was separated from it by flood control levees during the last two centuries (Kesel, 1988, 1989; Mossa, 1996; Roberts, 1997)...

    Robert R. LaneChristopheret al. Hydrologic and nutrient dynamics of a coastal bay and wetland receivin...

    • ...However, in the latest phases of WSR, SPM decreased due to sediment depletion in the channel system (Mossa, 1996; Asselman, 1999; Steegen et al., 2000) (Fig. 2). The suspended particles transported during WSR were mainly from the channel, which was characterized by clockwise hysteresis (Fig. 7a)...

    He Huijunet al. The hydrological regime and particulate size control phosphorus form i...

    • ...This assumption, however, may be overly optimistic; see the extensive discussion of errors in sediment-rating-curve methods by Horowitz (2003)...

    Robert H. Meadeet al. Causes for the decline of suspended-sediment discharge in the Mississi...

    • ...Mississippi delta because it is the largest river-dominated delta for which we have good records of bathymetry, water and sediment discharge, and their change in time [Keown et al., 1986; Mossa, 1996; Corbett et al., 2006]...
    • ...North American continent, draining more than 3.2 million km 2 . Mean annual water inflow into the delta in the last century is estimated at about Q = 17000 m 3 /s with rather low interannual variability [Mossa, 1996]...

    H. J. Seyboldet al. Simulation of birdfoot delta formation with application to the Mississ...

    • ...[3] TheAtchafalayaRiverdischargesintoAtchafalayaBay and adjacent shelf nearly 30% of the total water and sediment carried by the Mississippi River [Mossa, 1996], with an average suspended sediment load (calculated at Simmesport, LA, over the 1951–2000 period) of 84 million tons/a that includes 17% sand [Allison et al., 2000]...
    • ...Aside from tropical cyclones, the area has on average a low energy wave climate, with the notable exception of the period between February and April, when strong winds associated with atmospheric cold fronts pass over the area at 3 to 10-day intervals [Mossa, 1996; Roberts et al., 1989; Walker and Hammack, 2000; Kineke et al., 2006]...

    S. Jaramilloet al. Wave-mud interactions over the muddy Atchafalaya subaqueous clinoform,...

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