Floodplain sedimentation in the Upper Mississippi Valley: Natural versus human accelerated

Knox, James C.

doi:10.1016/j.geomorph.2006.06.031

Cited by 316 publications

(261 citation statements)

References 59 publications

(117 reference statements)

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“…The marked change of the overbank lithofacies toward silty overbank sediments associated to the Late Holocene time frame supports this explanation. The relative coarsening of the overbank deposits is most likely the result of human-induced soil erosion in the loess areas upstream (as found elsewhere, e.g., Knox, 2006). Large-scale deforestation during the Bronze Age, Iron Age, and Roman times in the hinterland (e.g., Friedmann, 2000;Singer, 2004;Lechner, 2005;Bos et al, 2008) resulted in significant changes in sediment availability.…”

Section: Human Influence On Terrace Formationmentioning

confidence: 73%

“…Terrace formation within the last glacial-interglacial cycle occurs because of allogenic (climate change, human impact, tectonics/base level changes) and autogenic controls (intrinsic behaviour and complex response). On this topic, numerous studies from large and small rivers spanning a range of climatic and physiographic settings have been published, with excellent examples from the Mississippi (e.g., Knox, 1996Knox, , 2001Knox, , 2006, Danube (e.g., Buch, 1988), Colorado (Blum and Valastro, 1994), Vistula/Weichsel (e.g., Starkel, 2002), some smaller rivers in the UK (e.g., Lewis et al, 2001;Gao et al, 2007), and the Meuse (e.g., Huisink, 1997;Tebbens et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

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Fluvial terrace formation in the northern Upper Rhine Graben during the last 20000 years as a result of allogenic controls and autogenic evolution

et al. 2009

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a b s t r a c t a r t i c l e i n f oThe northern Upper Rhine Graben hosts a well-preserved Late Weichselian and Holocene fluvial terrace sequence. Terraces differ in elevation, morphology, and overbank sediment characteristics. The purpose of this study was to determine the relative importance of allogenic controlling factors versus autogenic evolution on the successive formation of these terraces. For a representative valley segment (the Gernsheim region), results from previous research were integrated with newly obtained borehole data and digitized elevation maps to construct palaeogeographic maps and cross sections. Coarse-grained channel deposits below terrace surfaces were dated using Optically Stimulated Luminescence, and fine-grained abandoned channel fill deposits were dated using pollen stratigraphy and radiocarbon analysis. Initiation of terrace formation was caused by climatic change in the Late Pleniglacial (after~20 ka), but fluvial response was complex and slow and continued locally until the middle Boreal (~9 ka). Early to Middle Holocene (~6 ka) changes in fluvial style and associated overbank lithofacies are not necessarily controlled by climatic change as was previously proposed. Instead, autogenic processes combined with river reach-specific factors explain the observed terrace development. Continuous incision, autogenic evolution, and high preservation potential provide an alternative explanation for the presence of a terrace sequence in this subsiding area.

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Section: Human Influence On Terrace Formationmentioning

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Fluvial terrace formation in the northern Upper Rhine Graben during the last 20000 years as a result of allogenic controls and autogenic evolution

et al. 2009

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“…For the Rhine River, a cumulative sediment residence time of ~ 9 ky is based on careful sediment budgets (Hoffmann et al, 2007). A maximum sediment age constraint (16 ky) from stratigraphic sections is available for the Mississippi River (Knox, 2006), which we have also taken as an approximation for Mississippian tributaries (the Vermillion and Pearl Rivers), in the absence of measured rates. A measured upstream nuclide concentration, C up was used where available.…”

Section: Choice Of Model Parameters For Representative River Settingsmentioning

confidence: 99%

Cosmogenic nuclide budgeting of floodplain sediment transfer

Wittmann

Blanckenburg

2009

Geomorphology

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Cosmogenic nuclides produced in quartz may either decay or accumulate while sediment is moved through a river basin. A change in nuclide concentration resulting from storage in a floodplain is potentially important in large drainage basins in which sediment is prone to repeated burial and remobilization as a river migrates through its floodplain. We have modeled depth-and time-dependent cosmogenic nuclide concentration changes for 10 Be, The cosmogenic nuclide composition of old deposits in currently inactive floodplains that have been isolated for periods of millions of years from the river that once deposited them are predicted to either increase or decrease in C, nuclide concentrations modeled for the in situ-produced variety of this nuclide are, however, sensitive to floodplain storage on residence times of < 20 ky. 10 Be and 26 Al concentration, depending on the depositional depth. These conditions can be evaluated using the 26 Al/ 10 We illustrate these models with examples from the Amazon basin. As predicted, modern bedload collected from an Amazon tributary, the Bolivian Beni River, shows no systematic change in nuclide concentration as sediment is moved through 500 km of floodplain by river meandering. In contrast, in the central Amazon floodplain currently untouched by the modern river system, low Be ratio that readily discloses the depth and duration of storage.26 Al/ 10 The important result of this analysis is that in all likely cases of active floodplains, cosmogenic Be ratios account for minimum burial depths of 5 to 10 m for a duration of > 5 My. 10 Be and 26 Al concentrations remain virtually unchanged over the interval sediment usually spends in the basin. Thus, spatially-averaged denudation rates of the sediment-producing area can be inferred throughout the entire basin, provided that nuclide production rates are scaled for the altitudes of the sediment-producing area only, because floodplain storage does not modify nuclide concentrations introduced from the sediment source area.

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“…Increased surface runoff and erosion led to increased rates of floodplain sedimentation [Knox, 1987[Knox, , 2006. At the study site, this layer was between 0.1 and 1.2 m thick prior to restoration and generally decreased with lateral distance from the stream.…”

Section: Site Descriptionmentioning

confidence: 89%

Hydroecological model predictions indicate wetter and more diverse soil water regimes and vegetation types following floodplain restoration

Booth

Loheide

2012

J. Geophys. Res.

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[1] Transitions between aquatic and terrestrial ecosystems represent zones where soil moisture is a dominant factor influencing vegetation composition. Niche models based on hydrological and vegetation observations can be powerful tools for guiding management of these zones, especially when they are linked with physically based hydrological models. Floodplain restoration represents a unique opportunity to utilize such a predictive vegetation tool when a site's hydrology is altered to create a wetter environment. A variably saturated groundwater flow model was developed and used to simulate the soil moisture regime across a floodplain in Wisconsin where post-settlement alluvium was removed with the intent of increasing regionally threatened wetland plant species. Hydrological niche models based on simultaneous observations of vegetation composition and surface effective saturation were used to predict probability of presence for two plant species (Carex vulpinoidea (fox sedge) and Elymus canadensis (Canada wildrye)) and wetland indicator score (a composite indicator of relative frequency of species in five habitat categories) based on simulated surface effective saturation. The vegetation predictions following restoration are more wetland-species dominant overall. However, zones of the study site where a confining layer is present that decouples groundwater from the near-surface soil zone tend to be drier following restoration due to restricted upward groundwater flow and less soil water storage above the confining layer. As reflected by an increase in the interquartile range in the predicted wetland indicator score, this restoration technique may increase the site-scale spatial diversity of plant community types while simultaneously accomplishing the goal of increasing wetland plant species occurrence.Citation: Booth, E. G., and S. P. Loheide II (2012), Hydroecological model predictions indicate wetter and more diverse soil water regimes and vegetation types following floodplain restoration,

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Floodplain sedimentation in the Upper Mississippi Valley: Natural versus human accelerated

Cited by 316 publications

References 59 publications

Fluvial terrace formation in the northern Upper Rhine Graben during the last 20000 years as a result of allogenic controls and autogenic evolution

Fluvial terrace formation in the northern Upper Rhine Graben during the last 20000 years as a result of allogenic controls and autogenic evolution

Cosmogenic nuclide budgeting of floodplain sediment transfer

Hydroecological model predictions indicate wetter and more diverse soil water regimes and vegetation types following floodplain restoration

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