nyuuzyou/wikis huggingface dataset:
CSDMS 2011 annual meeting poster Wonsuck Kim

__NOTOC__
<FONT style="FONT-SIZE:10pt" color="#ffffff">Presentation provided during CSDMS annual meeting 2011</font>
=Sea-level rise, depth-dependent carbonate growth, and the paradox of drowned platforms=
Wonsuck Kim, University of Texas Austin Texas, USA. delta@jsg.utexas.edu
Abstract:
A mathematical model of carbonate platform sedimentation is presented in which the depth-dependent carbonate growth rate determines the depositional rate of a platform top responding to relative sea-level rise. This model predicts that carbonate platform evolution is primarily controlled by the initial water depth and the sediment production rate at the initial depth, rather than by the maximum potential production rate and imposed rate of relative sea-level rise. A long-standing paradox in the understanding of drowned carbonate platforms in the geological record is based on comparing relatively slow long-term rates of relative sea-level rise with maximum growth potentials of healthy platforms. The model presented here demonstrates that a carbonate platform could be paradoxically drowned by a constant relative sea-level rise when the rate is still less than the maximum carbonate production potential. This does not require other external controls of environmental change, such as nutrient supply or siliciclastic sedimentation. If the rate of relative sea-level rise is higher than the production rate at the initial water depth, the top of the carbonate platform gradually drops below the active photic zone and drowns even if the rate of relative sea-level rise is lower than the maximum carbonate accumulation growth potential. This result effectively resolves the paradox of a drowned carbonate platform. Test runs conducted at bracketed rates of relative sea-level rise have determined how fast the system catches up and maintains the “keep-up” phase, which is a measure of the time necessary for the basin to respond fully to the external forcing. The duration of the “catch-up” phase of platform response (termed carbonate response time) scales with the initial seawater depth and the platform-top aggradation rate. The catch-up duration can be significantly elongated with an increase in the rate of relative sea-level rise. The transition from the catch-up to the keep-up phases can also be delayed by a time interval associated with ecological reestablishment after platform flooding. The carbonate model here employs a logistic equation to model the colonization of carbonate-producing marine organisms and captures the initial time interval for full ecological reestablishment. The increase in delay time due to the carbonate response time and self-organized processes associated with biological colonization, implies a greater likelihood of autogenic origin for high-frequency cyclic strata than has been previously estimated. 
* Please acknowledge the original contributors when you are using this material. If there are any copyright issues, please let us know and we will respond as soon as possible.
CSDMS 2011 annual meeting poster Zachary Borden

__NOTOC__
<FONT style="FONT-SIZE:10pt" color="#ffffff">Presentation provided during CSDMS annual meeting 2011</font>
=Direct numerical simulation of sediment erosion=
Zachary Borden, UC Santa Barbara Santa Barbara California, United States. zborden@engineering.ucsb.eduEckart Meiburg, UC Santa Barbara Santa Barbara California, United States. meiburg@engineering.ucsb.eduMichael Glinsky, Commonwealth Scientific and Industrial Research Organization Perth NO STATE, Australia. Michael.Glinsky@csiro.auYuliya Kanarska, Lawrence Livermore National Laboratory Livermore California, United States. Kanarska1@llnl.gov
Abstract:
Any code that attempts to simulate large scale geophysical flows and their effect on topography needs a way to couple local flow properties to a rate of sediment erosion or deposition. However, the mechanisms responsible for a particle’s entrainment into a flow are poorly understood. Early erosional models setup a force balance between the fluctuating hydrodynamic forces acting on a particle and the adhesive forces holding a particle to the substrate. Later researchers eschewed this force balance in favor of an energy balance. They claim that a particle is constantly receiving energy from turbulent fluctuations in the flow near the surface, and that a particle will become entrained when it receives a critical amount of energy.
Despite all the work that has gone into deriving an erosion model based on theory, the most popular, and most accurate erosion model used in geophysical codes is the Garcia-Parker model, which is a simple fit to several sets of experimental data. But because their model is empirical, it’s impossible to know under what circumstances the model can and cannot be reasonably applied. A theoretical model would be much more desirable for precisely this reason.
Our goal is to better understand the mechanisms of particle entrainment through the use of direct numerical simulation. We are using a code developed at Lawrence Livermore National Laboratory, which solves the incompressible Navier-Stokes equations and uses a Lagrange multiplier method to enforce the correct boundary condition on the surface of the particles within the computational domain. With this method, we are able to accurately simulate the motion of thousands, or even tens of thousands of particles in an external flow in two or three dimensions. With this code, we can study in detail the coupling between local flow structures and the forces on a particle, which will hopefully lead to a better, theoretically based model for erosion. 
* Please acknowledge the original contributors when you are using this material. If there are any copyright issues, please let us know and we will respond as soon as possible.
CSDMS 2013 annual meeting poster Alan Howard

__NOTOC__
<FONT style="FONT-SIZE:10pt" color="#ffffff">Presentation provided during CSDMS annual meeting 2013</font>
=Simulating Fine-grained Alluvial Fan Sedimentation=
Alan Howard, University of Virginia Charlottesville Virginia, United States. ah6p@virginia.eduAlex Morgan, University of Virginia Charlottesville Virginia, United States. amm5sy@virginia.edu
Abstract:
The majority of process studies on alluvial fans have focused on gravely fans. Many fan systems, however, are sourced from basins composed of fine-grained sediments. Deposition on such fans involves deposition from hyperconcentrated- or mud-flows. Many of such fans occur where there is sufficient vegetation to affect and, often, obscure depositional processes. 
 
The modeling effort to be presented is motivated by the occurrence of fine-grained alluvial fans on Mars that feature a network of distributaries floored with coarser sediment and what we interpret to be fine-grained overbank deposits that comprise the bulk of the sediment. We have identified active fine grained fans in the arid Atacama desert deriving sediment from the higher Andes and lowland deposition dominated by muddy sheetflow sediment.
We are constructing a simulation model for deposition on such fans based on the fan-delta model of Sun et al. (2002). The model routes water and sediment through multiple distributaries that can branch, recombine, and avulse. Modeling flow and bedload sediment through the distributaries is relatively straightforward, but overbank deposition and avulsion processes are more problematic to characterize realistically (e.g. avoiding development of "holes" in fans or preventing evolution to a fixed distributary pattern). Our observation of overbank processes on the Atacama fans demonstrates the importance of sedimentation by long shallow sheetflow floods in addition to local levee aggradation. These processes are being implemented into our fan model.
* Please acknowledge the original contributors when you are using this material. If there are any copyright issues, please let us know and we will respond as soon as possible.
CSDMS 2013 annual meeting poster Alberto Canestrelli

__NOTOC__
<FONT style="FONT-SIZE:10pt" color="#ffffff">Presentation provided during CSDMS annual meeting 2013</font>
=A volume of fluid method for bank erosion in Delft3D=
Alberto Canestrelli, Department of Geosciences, Penn State Univeristy Boulder Pennsylvania, United States. auc26@psu.eduRudy Slingerland, Penn State University University Park Pennsylvania, United States. sling@geosc.psu.edu
Abstract:
By using a fixed-mesh approach, morphodynamic models have some difficulty to predict realistic equilibrium hydraulic geometries with vertical banks. In order to properly account for bank erosion without resorting to a complicated moving mesh algorithm, an immersed boundary approach that handles lateral bank retreat through fix computational cells is needed.
One of the main goals of the FESD Delta Dynamics Collaboration is developing a tested, high-resolution quantitative numerical model to predict the coupled morphologic and ecologic evolution of deltas from engineering to geologic time scales. This model should be able to describe the creation and destruction of deltas made of numerous channels, mouth bars, and other channel-edge features, therefore requiring an approach that is able to deal with the disruption, destruction, and creation of sub-aerial land. In principle, these sub-aerial land surfaces can be randomly distributed over the computational domain. 
We propose a new approach in Delft3D based on the volume of fluid algorithm, widely used in the literature for tracking moving interfaces between different fluids. We employ this method for implicitly tracking moving bank interfaces. This approach easily handles complicated geometries and can easily tackle the problem of merging or splitting of dry regions characterized by vertical vegetated banks.
* Please acknowledge the original contributors when you are using this material. If there are any copyright issues, please let us know and we will respond as soon as possible.
CSDMS 2013 annual meeting poster Alejandra Ortiz

__NOTOC__
<FONT style="FONT-SIZE:10pt" color="#ffffff">Presentation provided during CSDMS annual meeting 2013</font>
=A Mophodynamic Explanation for the Shoreface Depth of Closure=
Alejandra Ortiz, Woods Hole Oceanographic Institution Woods Hole Massachusetts, United States. aortiz@mit.eduAndrew Ashton, Woods Hole Oceanographic Institution Woods Hole Massachusetts, United States. aashton@whoi.edu
Abstract:
This research aims to understand the evolution of the shoreface of sandy, wave-dominated coasts. Using energetics-based formulations for wave-driven sediment transport, we develop a robust methodology for estimating the morphodynamic evolution of a cross-shore beach profile. We compare how shallow water wave assumptions and linear Airy wave theory affect the estimation of morphodynamic shoreface evolution, in contrast to previous work, which has applied shallow water wave assumptions across the entire shoreface. The derived cross-shore sediment flux formula enables the calculation of a steady state (or dynamic equilibrium) profile based on three components of wave influence on sediment transport: two onshore-directed terms (wave asymmetry and wave drift) and an offshore-directed slope terms. Equilibrium profile geometry depends on wave period and grain size. The profile evolution formulation yields a morphodynamic Péclet number that can be analyzed in terms of perturbations around the steady-state profile. The diffusional, offshore-directed slope term dominates long-term profile evolution. A depth-dependent characteristic timescale of diffusion allows the estimation of an effective morphodynamic depth of closure for a given time envelope. Theoretical modeled computations are compared to four field sites along the Eastern US coastline. For each of these four field sites, we use hindcast wave data to determine a representative wave height and period using a weighted frequency-magnitude approach. Using the characteristic wave quantities for each site, we compute the equilibrium profile and the morphodynamic depth of closure, showing reasonable similarities between the computed equilibrium profiles and the actual profiles. In addition, the estimated morphodynamic depth of closure matches well with the location of the visually estimated depth of closure (based upon slope break) for each site. Overall, the methodology espoused in this paper can be used with relative ease for a variety of sites and with varied sediment transport equations.
Modeled characteristic timescale of diffusivity using linear theory over depth with varying (a) deep-water wave height with T =8 s and (b) varying wave period with H0 = 1 m.
* Please acknowledge the original contributors when you are using this material. If there are any copyright issues, please let us know and we will respond as soon as possible.
CSDMS 2013 annual meeting poster Andrea DAlpaos

__NOTOC__
<FONT style="FONT-SIZE:10pt" color="#ffffff">Presentation provided during CSDMS annual meeting 2013</font>
=Biologic-Geomorphic feedbacks that sculpt tidal landscapes=
Andrea D'Alpaos, University of Padova Padova , Italy. andrea.dalpaos@unipd.itMarco Marani, Duke University South Carolina, United States. marco.marani@duke.edu
Abstract:
Tidal systems are biogeomorphic systems of great relevance, providing important ecosystem services and coastline protection against storms. The dynamics of these systems, currently threatened by the acceleration in the rate of global sea level rise (SLR) and the decrease in sediment supply, are governed by complex interactions between hydrological, ecological, and geomorphological processes. How do salt-marsh ecosystems respond to changes in the environmental forcings? What is the role physical and biological processes and of their interactions through eco-geomorphic feedbacks in controlling salt-marsh dynamic response to these changes and the existence of possible equilibrium states? To address these important issues and improve our understanding of the chief eco-geomorphic processes controlling salt-marsh response to current changes, we have developed a suite of eco-morphodynamic models accounting for complex two-way interactions between ecological and geomorphological processes. We find that vegetation crucially affects the equilibrium marsh elevation, marsh resilience to accelerations in SLR rates, and the morphological features of salt marsh channels. As soon as the platform is colonized by vegetation, plants crucially affect the local hydrodynamic circulation, favor channel incision, enhance particle settling by a reduction of turbulence levels within the canopy, promotes trapping sediment, and provides organic material. Model results suggest that highly productive and sediment-rich marshes will approach new equilibrium states in response to changes in the rate of SLR faster than sediment-poor or less productive marshes. Moreover, marshes exposed to large tidal ranges are more stable, and therefore more resilient to changes in the rate of SLR, than their microtidal counterparts. We also find that marshes are more resilient to a decrease rather than to an increase in the rate of SLR, and they are more resilient to a decrease rather than to an increase in sediment availability. Our modeling approaches emphasize that biological and physical interactions are crucial in determining the observed spatial patterns in the biological and in the geomorphic domains. The existence of feedbacks between physical and biological processes affects the evolutionary trajectories of saltmarsh ecosystems, and the reversibility of such trajectories, thus highlighting the importance of accounting for biogeomorphic feedbacks to obtain realistic representations of the system dynamics in response to climatic changes.
* Please acknowledge the original contributors when you are using this material. If there are any copyright issues, please let us know and we will respond as soon as possible.
CSDMS 2013 annual meeting poster Andrew Ashton

__NOTOC__
<FONT style="FONT-SIZE:10pt" color="#ffffff">Presentation provided during CSDMS annual meeting 2013</font>
=On a Neck, On a Spit=
Andrew Ashton, WHOI Woods Hole Massachusetts, United States. aashton@whoi.edu
Abstract:
Recurved barrier spits occur in a wide variety of environments, from active delta complexes to rocky coasts, where spits extend depositionally from a shore that is otherwise eroding. Although controls on spit orientation are often presented in the literature a posteriori (i.e. after the spit has been observed), there surprisingly remains no general model that predicts spit shape and orientation in terms of external variables, such as wave climate, sediment supply, and embayment depth. We study spit shape controls using the Coastline Evolution Model (CEM), a numerical model that evolves the plan-view coast based upon the processes of alongshore sediment transport and barrier overwash maintaining a minimum critical barrier width. Model results demonstrate that the directional distribution of approaching waves serves as a first-order control on spit shape, with waves from multiple directions playing a vital role in spit extension and reshaping. Surprisingly, we find that boundary effects, namely the rate of change of the updrift coast location, play a similarly important role in spit shape. The depth of the platform upon which a spit grows plays another important role, with deeper platforms tending to accommodate more sharply curved spits. Every day, spits act as a type of messenger in disguise, revealing wave forcing, sediment supply, and local geometry.
* Please acknowledge the original contributors when you are using this material. If there are any copyright issues, please let us know and we will respond as soon as possible.
CSDMS 2013 annual meeting poster Andrew Nicholas

__NOTOC__
<FONT style="FONT-SIZE:10pt" color="#ffffff">Presentation provided during CSDMS annual meeting 2013</font>
=Morphodynamic modeling of large anabranching rivers=
Andrew Nicholas, University of Exeter Exeter , United Kingdom. a.p.nicholas@exeter.ac.uk
Abstract:
The morphodynamics of large anabranching sand-bed rivers is investigated using a numerical model of hydrodynamics, sediment transport, bank erosion and floodplain development, operating over periods of several hundred years. Model sensitivity to key parameters is examined, and simulated channel and natural river morphology are compared in terms of the statistical characteristics of channel width, depth and bar shape distributions, and mechanisms of unit bar, compound bar and island evolution. Model results provide insight into controls on the frequency of mobile sand bars and the stability of larger vegated islands. 
* Please acknowledge the original contributors when you are using this material. If there are any copyright issues, please let us know and we will respond as soon as possible.
CSDMS 2013 annual meeting poster Anna Kelbert

__NOTOC__
<FONT style="FONT-SIZE:10pt" color="#ffffff">Presentation provided during CSDMS annual meeting 2013</font>
=A vision for EarthCube from the perspective of solid Earth geophysics=
Anna Kelbert, Oregon State University Corvallis Oregon, United States. anya@coas.oregonstate.edu
Abstract:
A major challenge of geophysics today is addressing the problems of general interest through intense collaboration that bridges disciplinary boundaries. Such collaborations are greatly complicated by the fact that Earth Sciences have steadily diverged and evolved to the point of the Tower of Babel. Scientific jargon makes it difficult to meaningfully explore ideas across disciplines, while lack of cyberinfrastructure for sharing causes poor reproducibility and code reuse. 
My vision for an EarthCube frontend is that of a maximally simple API that could be run from any platform or in a browser. At it's core, it would support the following functionality:
# make it really simple for someone to submit their own data, models and software with provenance and descriptive metadata;
# support data discovery in 4D space, at a range of scales, through semantically-enabled metadata (and the data might - and will - be stored in one of the existing databases);
# have potential for elaborate visualization capabilities;
# build up upon a social network of some sort (so that there's a face behind each data component); and, finally,
# make it easy to create, modify and run workflows remotely through intelligent combination of software and data components.
The last point seems critical for long term useability of EarthCube, and requires upfront thinking and code coupling capabilities.
Specifically, the plug-and-play component programming approach used by CSDMS could be adapted by the larger solid Earth geophysics community with great long-term benefits, hopefully resulting in better scientific reproducibility, code reuse and, eventually, streamlined collaboration.
* Please acknowledge the original contributors when you are using this material. If there are any copyright issues, please let us know and we will respond as soon as possible.
CSDMS 2013 annual meeting poster Ben Hudson

__NOTOC__
<FONT style="FONT-SIZE:10pt" color="#ffffff">Presentation provided during CSDMS annual meeting 2013</font>
=Model-Assisted River Discharge Estimates=
Ben Hudson, University of Colorado/ CSDMS Boulder Colorado, United States. Benjamin.Hudson@colorado.edu
Abstract:
Often a rivers discharge is calculated by constructing an empirical relationship between concurrent, direct measurements of river stage and discharge. In many remote parts of the world however technical and logistical challenges make building of such relationships difficult. 
We test and present an alternative approach for use in remote Greenlandic Rivers. We used in-situ stage observations, but converted these measurements into estimates of discharge using a fluid mechanically based model (Kean and Smith, 2005; Kean et al., 2009; Kean and Smith, 2010). We first tested this approach against the one river in Greenland with a well-developed empirical stage- discharge relationship. Modeled relationships agreed well with the empirically derived relationship. We then used this same technique to aid in estimating discharge on two additional rivers in Greenland where only stage measurements were available. This technique presents an alternative option when other methods are logistically prohibitive. In the future this approach may also be useful to aid in estimating river discharge from space. 
* Please acknowledge the original contributors when you are using this material. If there are any copyright issues, please let us know and we will respond as soon as possible.