Enhancing mud supply from the Lower Missouri River to the Mississippi River Delta USA: Dam bypassing and coastal restoration

Kemp, G. Paul; Day, John W.; Rogers, J. David; Giosan, Liviu; Peyronnin, Natalie

doi:10.1016/j.ecss.2016.07.008

Cited by 38 publications

(16 citation statements)

References 35 publications

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“…The morphological evolution of the Lower Mississippi River's bed is significantly complicated by a number of anthropogenic and natural factors whose onsets overlap in time: diversion to the Atchafalaya River and Bonnet Carre Spillway (Allison et al, 2013; Fisk, 1952; Roberts et al, 2003); upstream changes to sediment supply by dams and bank stabilization efforts (Kemp et al, 2016; Tweel & Turner, 2012); substantial channel shortening by cutoffs (Biedenharn et al, 2000); and a flow confining levee system (Barry, 1998). As a result, no simple explanation of the current bed morphology is appropriate.…”

Section: Resultsmentioning

confidence: 99%

Flow Loss in Deltaic Distributaries: Impacts on Channel Hydraulics, Morphology, and Stability

Esposito

Georgiou

Straub

2020

Water Resources Research

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The most comprehensive data sets documenting hydraulic and sediment transport regimes in the lower reaches of alluvial rivers come from systems that are managed to prevent flow loss from the channel into the overbank environment. Even moderate losses can have significant impacts on in-channel velocity and sediment transport; therefore, a full understanding of flow loss and its effects is an important prerequisite to insights into channel function and to designing effective management strategies. We use the term flow loss for losses of water that are locally small relative to the main channel discharge. We present a unique data set documenting discharge, channel geometry, and water surface elevation from three distributary channel networks in the Mississippi River Delta where flow loss is widespread. We apply our data to validate a 1-D hydraulic model, which then drives a previously validated model of sediment transport. Results from the modeling effort demonstrate that velocity and sediment transport trends are substantially modulated by flow loss in the ranges observed in distributary networks. The effect of flow loss on distributary channels established, we then examine how flood control infrastructure may have impacted the morphological evolution of the lowermost reaches of a large alluvial river like the Mississippi. The expected outcome of preventing flow loss is erosion in the channel's lowermost reach, in agreement with observational data. Finally, we develop a theoretical metric for a stable channel, and show that flow loss is a potentially important and understudied contributor to the long-term behavior of distributary channels.

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Section: Resultsmentioning

confidence: 99%

Flow Loss in Deltaic Distributaries: Impacts on Channel Hydraulics, Morphology, and Stability

Esposito

Georgiou

Straub

2020

Water Resources Research

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“…Reducing the continued decline in Mississippi River fine-grained sediment flux is very important now that river diversions are being built for coastal wetland restoration in the deltaic plain. Kemp et al [10] concluded that tributary dam bypassing in the Lower Missouri basin could increase mud supply to the Mississippi River delta by 100-200 Mt yr −1 within 1-2 decades. Such measures to restore the Mississippi delta are compatible with objectives of the Missouri River Restoration and Platte River Recovery Programs to restore riparian habitat for endangered species [10].…”

Section: The Potential To Increase Basin Sediment Inputmentioning

confidence: 99%

“…This 50-year Coastal Master Plan (CMP) is being conceived, amended and constructed at the same time that massive global change is also taking place [1][2][3]). Deltas are among the coastal systems most threatened by climate change because the stability of the land itself-lying at or close to sea level-is affected by new interactions among stressors that arise in the upstream reaches of watersheds as well as from the coastal ocean [4][5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

The “Problem” of New Orleans and Diminishing Sustainability of Mississippi River Management—Future Options

Day

Hunter²,

Kemp

et al. 2021

Water

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Climate change forcings are having significant impacts in coastal Louisiana today and increasingly affect the future of New Orleans, a deltaic city mostly below sea level, which depends on levee and pumps to protect from a host of water-related threats. Precipitation has increased in the Mississippi River basin generally, increasing runoff, so that in recent years the Mississippi River has been above flood stage for longer periods of time both earlier and later in the year, increasing the likelihood that hurricane surge, traditionally confined to summer and fall, may compound effects of prolonged high water on river levees. The Bonnet Carré Spillway, just upstream of New Orleans has been operated more often and for longer periods of time in recent years than ever before in its nearly 100-year history. Because all rain that falls within the city must be pumped out, residents have been exposed to interior flooding more frequently as high-intensity precipitation events can occur in any season. A sustainable path for New Orleans should involve elevating people and sensitive infrastructure above flood levels, raising some land levels, and creating water storage areas within the city. Management of the lower Mississippi River in the future must include consideration that the river will exceed its design capacity on a regular basis. The river must also be used to restore coastal wetlands through the use of diversions, which will also relieve pressure on levees.

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“…As a result, mitigation schemes aimed at reducing future losses are commonly based on increasing sediment supply, principally inorganic sediments (mud, sand), to the deteriorating marshes (CPRA, 2007(CPRA, , 2012(CPRA, , 2013(CPRA, , 2016Day et al, 2007). Although a current debate concerns the relative importance of marinegenerated sediment (delivered by tropical cyclones) vs. fluviallydelivered terrestrial material (Turner et al, 2006(Turner et al, , 2007Törnqvist et al, 2007;Turner, 2012, 2014;Smith et al, 2015), the value of mineral deposition in mitigating the negative effects of rSLR rise is treated as a given (Delaune et al, 1978;Blum and Roberts, 2009;Allison and Meselhe, 2010;Day et al, 2011;Stralberg et al, 2011;Allison et al, 2012;Kemp et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

The Effects of Tropical Cyclone-Generated Deposition on the Sustainability of the Pearl River Marsh, Louisiana: The Importance of the Geologic Framework

et al. 2018

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Shoreline retreat is a tremendously important issue along the coast of the northern Gulf of Mexico, especially in Louisiana. Although this marine transgression results from a variety of causes, the crucial factor is the difference between marsh surface elevation and rising sea levels. In most cases, the primary cause of a marsh's inability to keep up with sea level is the lack of input of inorganic material. Although tropical cyclones provide an important source of such sediment, little effort has been made to determine the point of origin of the deposited material. In this study we use sedimentary, geochemical and biogeochemical data to identify the bed of the Pearl River and/or Lake Borgne as the source of a ∼5 cm thick clastic layer deposited on the surface of the Pearl River marsh on the Louisiana/Mississippi border. Radiochemical chronologies and sedimentary evidence indicate that this layer was associated with the passage of Hurricane Katrina in 2005. As this material would otherwise have been lost to the system, this deposition indicates a net gain to marsh surface elevation. Accretion rates, determined from 137Cs and 14C profiles and the use of the Katrina layer as a stratigraphic marker, indicate that short-term (∼50 years) rates are as much as an order of magnitude higher than the long-term (1000s of years) rates. We suggest that the marsh's geologic setting in an incised river valley with steep vertical constraints and a large fluvial discharge, promotes rapid accretion rates, with rates accelerating as the sea moves inland, due to extended hydroperiods and the input of clastic material from both the marine and terrestrial sides. These rates are especially large when compared to accretion occurring in the more common open marshes fringing the Gulf that lack fluvial input. The difference is particularly large when related to marsh recovery/regrowth following the deposition of thick hurricane-generated clastic layers. Given the number of similar incised river valleys along the Gulf Coast, we believe that understanding the processes controlling marsh accretion in such environments is essential in evaluating marsh sustainability on a regional basis.

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Enhancing mud supply from the Lower Missouri River to the Mississippi River Delta USA: Dam bypassing and coastal restoration

Cited by 38 publications

References 35 publications

Flow Loss in Deltaic Distributaries: Impacts on Channel Hydraulics, Morphology, and Stability

Flow Loss in Deltaic Distributaries: Impacts on Channel Hydraulics, Morphology, and Stability

The “Problem” of New Orleans and Diminishing Sustainability of Mississippi River Management—Future Options

The Effects of Tropical Cyclone-Generated Deposition on the Sustainability of the Pearl River Marsh, Louisiana: The Importance of the Geologic Framework

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