Sediment flux from rivers to oceans is the fundamental driver of fluvio‐deltaic morphodynamics and continental margin sedimentation, yet sediment transport across river‐to‐marine boundary poorly understood. Coastal typically are affected by backwater, a zone spatially decelerating flow that transitional between normal upstream offshore river plume. Flow deceleration in backwater zone, as well spreading plume, should render highly depositional near their mouths, leading sedimentation eventual...

Research Article| March 01, 2012 Spatial and temporal trends for water-flow velocity bed-material sediment transport in the lower Mississippi River Jeffrey A. Nittrouer; Nittrouer † 1Department of Geological Sciences, University Texas, 1 Station C9000, Austin, Texas 78712, USA †Current address e-mail: Department Geology, Illinois at Urbana-Champaign, 253 Natural History Building, Urbana, 61801, USA; jeffnitt@illinois.edu Search other works by this author on: GSW Google Scholar John Shaw;...

Abstract River deltas are classic depositional systems, but a growing body of literature shows that their channel networks can be erosional. Furthermore, this erosion attack beds consolidated mud acts as bedrock. To better understand the natural and engineered river diversions, we investigate bathymetric planimetric change, bed cover, sediment transport in Wax Lake Delta (WLD) coastal Louisiana, USA. Channels have eroded up to 40% modern flow depth between WLD's initiation 1973 1999. Aerial...

Research Article| January 01, 2014 The importance of erosion in distributary channel network growth, Wax Lake Delta, Louisiana, USA John B. Shaw; Shaw Jackson School Geosciences, University Texas at Austin, C9000, 78712, *Current address: Department Geology and Geophysics, Wyoming, 3006, Laramie, Wyoming 82071, USA. Search for other works by this author on: GSW Google Scholar David Mohrig Author Article Information Publisher: Geological Society America Received: 20 May 2013 Revision 11 Sep...

At a global scale, delta morphologies are subject to rapid change as result of direct and indirect effects human activity. This jeopardizes the ecosystem services deltas, including protection against flood hazards, facilitation navigation, biodiversity. Direct manifestations morphological instability include river bank failure, which may lead avulsion, persistent channel incision or aggregation, sedimentary regime hyperturbid conditions. Notwithstanding in‐depth knowledge developed over past...

Turbid river plumes entering ocean or lake water of lesser density (i.e., hyperpycnal plumes) can plunge to form turbidity currents providing an important link between terrestrial sediment sources and marine depositional sinks. A leading hypothesis suggests that hyperpycnal-plume deposits accurately record the rising falling discharge a flooding (in terms sediment-size grading, bedform sequence, deposit thickness), which, if correct, has significant implications for unraveling dynamics,...

Abstract The transition of flow between laterally confined channels and the unchannelized delta front controls morphodynamic evolution river deltas but has rarely been measured at field scale. We quantify patterns bathymetry that define subaqueous on Wax Lake Delta, a rapidly prograding in coastal Louisiana. A significant portion (∼59%) departs channel network over lateral margins as opposed to downstream tips. Bathymetric surveys remotely sensed estimates direction allow spatial changes...

Abstract Sediment is the most valuable natural resource for deltaic environments because it required to build new land. For land building occur, sediment must be retained in delta instead of being transported offshore. Despite this, we do not know what controls retention within a delta. Here use calibrated numerical model Wax Lake Delta, Louisiana, USA analyze different riverine flood magnitudes, tidal amplitudes, and vegetation extents. Our results show that as magnitude increases, areally...

Research Article| December 01, 2011 Topset-dominated deltas: A new model for river delta stratigraphy Douglas A. Edmonds; Edmonds * 1Department of Earth and Environmental Sciences, Boston College, 140 Commonwealth Avenue, Devlin Hall 213, Chestnut Hill, Massachusetts 02467, USA *E-mail: douglas.edmonds@bc.edu Search other works by this author on: GSW Google Scholar John B. Shaw; Shaw 2Jackson School Geosciences, University Texas, 1 Station C1100, Austin, Texas 78712-0254, David Mohrig Author...

Global coastlines and their dense populations have an uncertain future due to increased flooding, storms, human modification. The distributary channel networks of deltas marshes that plumb these present diverse architectures, including well-studied dendritic topologies. However, the quasi-stable loops are frequent in many coastal not yet been explained. We a model for self-organizing inspired by vascular biophysics show emerge when relative forcings between rivers tides comparable, resulting...

The ready availability of satellite and other images the Earth together with increasing societal interest in coastal processes morphology make it desirable to have a consistent way defining mapping shorelines from images. obvious choice, land‐water interface, is inadequate because includes back sides islands edges river tidal channels that are not directly exposed open water. On complex coasts, inclusion these portions interface would significantly affect quantitative measures shoreline...

Abstract Coastal wetland systems are among the most dynamic landscapes on Earth's surface; however, interrelated processes create platforms that relatively constant in space and time. Theoretically, “stable” elevations should maintain themselves through time if balance of creating elevation remains unchanged. At Louisiana's prograding Wax Lake Delta, we measure landscape change between 2009 2013, quantifying volumetric changes to delta, subaerial slope adjustment, an equilibrium 0.56 m North...

Research Article| February 01, 2015 Tracking hurricane-generated storm surge with washover fan stratigraphy John Shaw; Shaw * 1Department of Geosciences, 216 Ozark Hall, University Arkansas, Fayetteville, Arkansas 72701, USA2Jackson School Texas at Austin, C9000, 78712, USA3Department Geology and Geophysics, Department 3006, Wyoming, Laramie, Wyoming 82071, USA *E-mail: shaw84@uark.edu Search for other works by this author on: GSW Google Scholar Yao You; You 2Jackson †Current address: Hess...

Abstract Coastal and deltaic sediment balances are crucial for a region's sustainability. However, such remain difficult to quantify accurately, particularly large regions. We calculate organic mineral mass volume using field measurements from 273 Coastwide Reference Monitoring System sites across the Louisiana Coast between 2006 2015. The rapid relative sea level rise rate (average 13.4 mm/year) is offset by small dry bulk densities observed 0.3 g/cm 3 ) produce 16.2 ± 41.1% deficit 24.1...

Abstract Shallow coastal regions are among the fastest evolving landscapes but notoriously difficult to measure with high spatiotemporal resolution. Using Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) data, we demonstrate that signal‐to‐noise L band synthetic aperture radar (SAR) can reveal subaqueous channel networks at distal ends of river deltas. 27 UAVSAR images collected between 2009 and 2015 from Wax Lake Delta in Louisiana, USA, show under normal tidal conditions,...

Abstract We show that distributary channels on river deltas exhibit a mean bifurcation angle can be understood using theory developed in tributary channel networks. In certain cases, network geometries have been demonstrated to controlled by diffusive groundwater flow feeding incipient bifurcations, producing characteristic of 72 ∘ . measured 25 unique bifurcations an experimental delta and 197 10 natural deltas, yielding 70.4 ±2.6 (95% confidence interval) for field‐scale 68.3 ±8.7 the...

Adaptive transport networks are known to contain loops when subject hydrodynamic fluctuations. However, fluctuations no guarantee that a loop will form, as shown by loop-free driven oscillating flows. We provide complete stability analysis of the dynamical behavior any formed fluctuating find threshold for involves an interplay geometric constraints and forcing mapped constant components. Loops require fluctuation in relative size flux between nodes, not just temporal variation at given...

Abstract Island formation and distributary channel branching are important processes in prograding river deltas. We develop test a new theory predicting the distance to islands bifurcations based on fluid mass conservation radially symmetric transport conditions. analyze channelization island using nine five existing delta experiments as well four field The were designed produce from initial deposition of mouth bar. Before formation, each bar evolved into deposit with unchannelized flow over...

Abstract Understanding the incomplete nature of stratigraphic record is fundamental for interpreting sequences. Methods quantifying completeness one‐dimensional columns, defined as proportion time intervals some length that contain stratigraphy, are commonplace; however, quantitative assessments in higher dimensions lacking. Here we present a metric defining two‐dimensional shoreline trajectories using topset‐foreset rollover positions dip‐parallel sections and describe preservation...

We propose an exploratory model to describe the morphodynamics of distributary channel network growth on river deltas. The interface between deep channels and shallow, unchannelized delta front deposits is modeled as a moving boundary. Steady flow over friction dominated by Laplace's equation. Shear stress along boundary produces nonlinear erosion rates at interface, causing move elements (channels branches) form. was run for conditions resembling Wax Lake Delta in coastal Louisiana, 20...

Abstract The backwater number, B w , compares the length scale to of alluvial bed forms. We derive theory show that plays an important role in determining behavior and scaling morphodynamic systems. When ≫ 1, spatial patterns deposition erosion from flow accelerations associated with changes depth, evolution is akin a kinematic wave. ≪ pattern shear stress determined by variations energy slope, beds experience topographic dispersion. This confirmed using numerical model data compiled...

Abstract. Remotely sensed flow patterns can reveal the location of subaqueous distal tip a distributary channel on prograding river delta. Morphodynamic feedbacks produce channels that become shallower over their final reaches before unchannelized foreset slopes basinward. The direction field this morphology tends to diverge and then converge, providing diagnostic signature be captured in or remote sensing data. A total 21 measurements from Wax Lake Delta (WLD) coastal Louisiana 317...