Property:CSDMS meeting abstract
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The shorelines of atoll reef islands (also called motu, sandy cays, or islets) frequently are the only available landforms in an atoll system, e.g. Kwajalein Atoll encompasses over 2174 km² but only 16 km2 of that area is emergent land, and thus understanding the drivers of coastal landscape evolution is vital. In particular, atolls are highly vulnerable to several threats of climate change from accelerated rates of sea level rise (causing flooding or potential drowning) to ocean acidification (decreasing coral reef resiliency) to ocean warming (causing coral bleaching). However, we lack a thorough understanding of the potential drivers of landscape change in these systems. In addition atolls can be exposed to high energy wave climates, however, the carbonate reef platform that encircles the inner lagoon of an atoll, commonly filters much of the incident wave energy. This reef platform or reef flat is typically shallow (1-2 m below MSL) with a near constant depth across the reef-flat width; the reef-flat widths range from a 100s meters to over a kilometer on different atolls. Both numerical modeling and field observations have found that these shallow reef-flats are key for driving wave breaking at the ocean edge of the reef flat offshore of the atoll reef islands and decreasing wave energy at the shoreline. As demand for construction materials increases, these carbonate reef platforms have been excavated, with large pits ranging from 10-80 m in width and average depths of 4 m. This study seeks to understand how the presence of excavation pits on reef flats change the wave energy at the shoreline. Utilizing 1D XBeach model, we investigate the impact of varying excavation pit geometry on the shoreline wave energy. We found that the presence of an excavation pit increases wave energy at the shoreline. +
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The stratigraphic record is the product of sedimentary processes acting over time. The Regional Ocean Modeling System (ROMS) includes algorithms for the processes of erosion, deposition, and mixing of both non-cohesive (sandy) and cohesive (muddy) sediment, and routines capable of tracking the evolution of event-scale stratigraphy with layers as fine as a few grain diameters thick. Thus ROMS allows users to relate process with product over time scales ranging from a few seconds to years, over vertical space scales of 0.1 mm to meters, and over horizontal space scales of meters to hundreds of kilometers. ROMS requires users to specify the number of bed layers to be tracked at compile time. This improves model efficiency on parallel systems, but complicates the task of tracking stratigraphic evolution. In addition to the number of layers, users can control the minimum and maximum layer thickness and the initial stratigraphy. The effect of these choices and the success of the stratigraphy routines is demonstrated with models of idealized estuaries, deltas, and continental shelves. +
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The surface geology of Late Cretaceous Western Interior Seaway (WIS) has been extensively studied, and many recent studies suggest the presence of dynamic loading due to flat slab subduction. However, it remains unclear how surface processes respond to tectonic forcing originated from either lithospheric flexural isostasy or sub-lithospheric mantle convection. Landscape evolution models represent an ideal tool to test the surface responses under different tectonic histories, each of which is designed to reflect a certain physical mechanism. In this research, we aim to use forward landscape evolution models to investigate the mechanisms accounting for the characteristics in the observed WIS stratigraphy. In our data-oriented landscape evolution models, where we test different scenarios of lithospheric and mantle forcing, the results suggest that only a geographically migratory subsidence can produce tilted strata and shifting depocenter, both of which are key features in the WIS sedimentary record. This implies that the tectonic subsidence of the WIS likely originated from deep mantle downwelling underneath the westward-moving North American plate. Furthermore, this migratory subsidence of mantle origin can also explain the continental drainage reorganization over middle North America after the WIS and the eastward-shifting sediment flux to the Gulf of Mexico during the Cenozoic. +
The tectonic stress fields induced by lateral and vertical variations in the lithosphere induce crustal deformation and lead to the development of fault and topography. Surface deformation and faulting influence channel processes, which may result in changes in drainage patterns. However, there are few studies that systematically compare and examine the connections among the lithospheric stress field, fault development, and observed drainage patterns on global scales. Here, we compare the directions of the lithospheric stress field, the development of fault and topography, and drainage flow patterns. First, we model the lithospheric stress field by computing the gravitational potential energy based on the crustal structure from Crust 1.0 augmented by a thermodynamically derived mantle thickness and density. We obtain the orientations of most and least compressive horizontal stresses and their inferred regimes and compare those with the World Stress Map (2016). We then extract the directions of active faults from the Global Earthquake Model Global Active Faults Database. Lastly, we extract the river flow paths and drainage network patterns from a digital elevation model from the steepest descent direction in the eight-direction flow. Our results show that there is a general correspondence between the predicted and observed patterns of fault orientation and river flow directions with the horizontal most compressive stress direction. The predicted correspondence among stress field, fault, and drainage patterns vary depending on the stress regime and channel order. We find that some locations show river flow patterns consistent with the predicted directions from fault and topographic development based on Anderson’s fault theory, but there are certain locations that show measurable deviations from the predicted patterns. We investigate those areas to better understand the interaction among shallow subsurface stress fields, surface topography, and drainage patterns.
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The tidal flats of Roberts Bank in British Columbia, Canada contain large areas of the intertidal zone that are vegetated with eelgrass (Zostera Marina and Zostera Japonica). This vegetation has a variable influence on the flow of tidal waters passing over the tidal flats, which we aim to describe in a large-scale 2D hydrodynamic model.
Vegetation on the surface of the tidal flats causes an increase in the roughness that modifies the flow properties. For submerged vegetation, this roughness is most strongly related to the height of the plants in the water; however, for very flexible plants such as eelgrass, the plant height changes with flow velocity since the plants bend with the currents. The roughness is therefore dependent both on flow depth and flow velocity.
Existing studies concerning the effect of flexible vegetation on flow are mostly focused on the small-scale properties of the velocity and turbulence profiles. Such results cannot be directly incorporated into 2D hydrodynamic models. 3D hydrodynamic modeling is computationally demanding and is therefore less appropriate for large-scale studies and engineering applications over large areas. In order to resolve this computational challenge we developed an integrated formulation of the effects of flexible vegetation on the flow, with the following approach: The roughness is represented through an equivalent Manning’s coefficient, which depends on both the water depth and the flow velocity.
Simulations are performed with the Telemac2d model, which has been modified to incorporate the velocity-dependent friction law. Preliminary results show that the proposed law is able to account for qualitative modifications in the tidal flow. In particular, the simulation provides an asymmetric flow pattern that correctly predicts the slower ebb velocities as compared to flood velocities, as observed in the field. +
The understanding of polar regions has advanced tremendously in the past two decades and much of the improved insight into our knowledge of environmental dynamics is due to multidisciplinary and interdisciplinary studies conducted by coordinated and collaborative research programs supported by national funding agencies. Although much remains to be learned with respect to component processes, many of the most urgent scientific, engineering and social questions can only be addressed through the broader perspective of studies on system scales. Questions such as quantifying feedbacks, understanding the implications of sea ice loss to adjacent land areas or society, resolving future predictions of ecosystem evolution or population dynamics all require consideration of complex interactions and interdependent linkages among system components. Research that has identified physical controls on biological processes, or quantified impact/response relationships in physical and biological systems is critically important, and must be continued; however we are approaching a limitation in our ability to accurately project how the Arctic and the Antarctic will respond to a continued warming climate. Complex issues, such as developing accurate model algorithms of feedback processes require higher level synthesis of multiple component interactions. Several examples of important questions that may only be addressed through systems analyses will be addressed. +
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The watershed of the Tapartó and Farallones rivers and the La Arboleda stream in the central zone of Colombia’s western mountain range are known to have experienced important debris flow events historically. In the same manner, there is geomorphological evidence that suggests a complex dynamic associated with the conditions of high slope, heavy rainfall and a soil profile with an important development.<br>The geomorphological analysis carried out in these watersheds enabled recognition of different levels of deposits in addition to their stratigraphic characterization. Likewise, radiocarbon dating allowed the establishment of ages between 100 +/- 30 and 2010 +/- 30 years for the different levels of deposits characterized. The integration of geomorphological and stratigraphic information along with radiocarbon dating allowed for the differentiation of the debris flow dynamics of each of the basins and suggests the existence of three phases. The first is an ancient one (with deposits older than 2000 years), followed by a sub-recent dynamic (represented by levels between 1500 and 2000 years old) and a current dynamic, with low incised deposits systems and ages that do not exceed 500 years. Finally, it was established that even though these basins have great potential for the generation of debris flow events of significant magnitude, the deposits show a tendency of decreasing magnitudes in the last 1000 years.<br>These analyses and their results are input to the construction of knowledge in relation to the understanding of this phenomenon in tropical environments and the generation of elements that would allow to address the problem in other zones with similar characteristics in throughout the country. +
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The west coast of North America is the setting for one of the world’s largest coastal upwelling regions. Large rivers drain from North America into the northern eastern Pacific Ocean, delivering large loads of sediments, as well as nutrients, organic matter and organisms. The Eel River discharges into the North Pacific just north of Cape Mendocino in Northern California. Its annual discharge (~200 m3/s) is about 1% that of the Mississippi, but its sediment yield (15 million tons/yr) is the highest for its drainage area (9500 km2) in the entire continental US. This strongly seasonal signal, generated largely by winter storm events that flush sediment and detritus into the river and down to the sea, generates dramatic nutrient pulses that may play a role in the timing and magnitude of offshore phytoplankton blooms. Understanding how the interannual variability of weather, moderated by slower trends in climate, affects these pulses, which in turn may alter offshore nutrient availability, is something we hope to explore through a detailed modeling framework. In our coupled modeling framework, the watershed is currently represented by the lumped empirical watershed model HydroTrend for its ability to generate high-frequency water and sediment time series in relatively unstudied basins. The atmosphere is represented by the NCEP North American Regional Reanalysis, a model and data assimilation tool. Eventually, we hope to represent the atmosphere with the Community Earth System Model, a powerful tool for studying climate change projections, which will let us talk about possible future impacts of climate change on coastal productivity. The ocean is represented with the Regional Ocean Modeling System, a powerful and very modular, physically distributed model that can efficiently solve fine-scale resolution grids. The coastal biology will be handled by modification of an iron-limited nutrient-phytoplankton-zooplankton-detritus model. +
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Theories for vertical bedrock river incision are well developed and widely applied; however, understanding how bedrock rivers laterally erode their banks and develop into wide bedrock valleys is a frontier topic in geomorphology. I use a modified version of the Landlab lateral erosion component coupled with the sediment-flux dependent vertical incision component in Landlab to explore the fundamental question of how valley width and widening rates are related to sediment on the channel bed. The lateral erosion component widens valleys through lateral undercutting and eventual collapse of bedrock valley walls. The modified lateral erosion component allows the user to set a characteristic block size of collapsed bedrock material. Collapsed material with smaller blocks sizes is rapidly transported away from the valley wall, allowing continued widening, while collapsed material with larger block sizes protects valley walls from further widening until it has weathered into transportable grain sizes. Model simulations show that valleys are wider in landscapes where collapsed material is closer in size to bedload sediment and narrower in landscapes where collapsed material is much larger than bedload sediment. I also use the newly modified lateral erosion/valley widening component together with additional Landlab components to explore the effects of variable discharge and changes in sediment flux on valley width and valley widening rates. This set of model experiments is a step towards a more nuanced and quantifiable framework for describing and predicting bedrock valley widening through time. Numerical models that include physical processes of valley widening are necessary for further advances of geomorphic applications such as numerical modeling of climate-driven strath terrace formation and hillslope–channel coupling. +
Theories for vertical bedrock river incision are well developed and widely applied; however, understanding how bedrock rivers laterally erode their banks and develop into wide bedrock valleys is a frontier topic in geomorphology. I use a modified version of the Landlab lateral erosion component coupled with the sediment-flux dependent vertical incision component in Landlab to explore the fundamental question of how valley width and widening rates are related to sediment on the channel bed. The lateral erosion component widens valleys through lateral undercutting and eventual collapse of bedrock valley walls. The modified lateral erosion component allows the user to set a characteristic block size of collapsed bedrock material. Collapsed material with smaller blocks sizes is rapidly transported away from the valley wall, allowing continued widening, while collapsed material with larger block sizes protects valley walls from further widening until it has weathered into transportable grain sizes. Model simulations show that valleys are wider in landscapes where collapsed material is closer in size to bedload sediment and narrower in landscapes where collapsed material is much larger than bedload sediment. I also use the newly modified lateral erosion/valley widening component together with additional Landlab components to explore the effects of variable discharge and changes in sediment flux on valley width and valley widening rates. This set of model experiments is a step towards a more nuanced and quantifiable framework for describing and predicting bedrock valley widening through time. Numerical models that include physical processes of valley widening are necessary for further advances of geomorphic applications such as numerical modeling of climate-driven strath terrace formation and hillslope–channel coupling. +
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Theories have been proposed using idealized tracer age modeling for ocean ventilation, atmospheric circulation, soil, stream and groundwater flow. In this research we developing new models for the dynamic age of water in hydroecological systems. Approaches generally assume a steady flow regime and stationarity in the concentration (tracer) distribution function for age, although recent work shows that this is not a necessary assumption. In this paper a dynamic model for flow, concentration, and age for soil water is presented including the effect of macropore behavior on the relative age of recharge and transpired water. Several theoretical and practical issues are presented. +
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There exists a rich understanding of channel forms and processes for rivers with unidirectional flows, and for their estuarine components with bidirectional flows. On the other hand, complementary insight on the transitional reach linking these flows has not been well developed. This study highlights the analyses of high resolution, high accuracy bathymetric surveys along a coastal plain river at 30 - 94 km upstream of the estuary mouth. The goal of this work is to identify geomorphic indicators of the fluvial-tidal transition channel. Trends with sharp breaks were detected in along-channel variations of depth, hydraulic radius, channel shape, bed elevation and sinuosity, but cross-section area of flow provided the greatest insight. The transition channel is characterized as a reach with greater than 50% decline in area of flow relative to the background values at the upstream and downstream ends. Further downstream the river is a mixed bedrock-alluvium system, and a 22 km reach of discontinuous bedrock outcrops has a marked influence on local channel metrics, and corresponding backwater effects on upstream metrics. Despite the confounding effects of bedrock on channel form the transition channel linking estuarine and fluvial channel segments is apparent as a 13 km geomorphic discontinuity in flow area along a channel reach of relatively uniform width. Finally, it is proposed that bedrock outcrops enhance tidal energy dissipation and influence the position of the fluvial-tidal transition reach, and associated geomorphic and hydrodynamic features. +
There is growing recognition that outwash events are potent agents of morphological change in some coastal regions. Outwash associated with inundation from the back side (bay, lagoon, sound, or marsh) occurred during Hurricane Harvey in Texas (2017) and Hurricane Dorian in North Carolina (2019). In both cases, floodwaters crossed the barrier islands and drained to the ocean through gaps in the primary dune lines, incising deep (~2-m) channels 30- 100-m wide in the islands and depositing the sand in the ocean. In both cases, partial recovery occurred within days and months as nearshore and beach processes generated spits, bars, berms, and overwash fans that rebuilt the beach and closed the channels, creating a series of ponds. Normally, washover deposits are quickly (1 – 2 years) revegetated with beach grasses that trap wind-driven sand and initiate dune building. However, in Texas, North Carolina, and several other locations where outwash channels were observed, the channels have remained largely unvegetated and no dunes have appeared. We have adapted a simple conceptual model to account for these observations. The model argues that the rate of vegetation growth depends, at least partially, on the amount of vegetation already present. In the case of overwash, material is deposited on older washover fans or platforms that contain live plants, seeds, rhizomes, and other organic material, and (following others) we suggest that the amount of vegetative material is a function of washover-deposit thickness. In contrast, when washout channels are filled, none of that material is present, and our model assigns these deposits very low initial amounts of vegetative material. Thus, vegetation growth on the two landscapes occurs at different rates, and the former outwash channels are unable to build elevation as quickly, leaving them continuously exposed to overwash events. A quantitative implementation of this model provides results that match well with observations at several sites.
This poster shows a top-down modeling work using a simple climate and economy model to examine pathways to achieve the climate stabilization targets stipulated in the Paris Agreement. A motivation for this presentation is to seek a possibility to complement this type of work with a bottom-up approach such as agent-based modeling so that climate mitigation pathways can be investigated from different angles.
In this work, we raise two issues: 1) Negative emission technologies such as Bioenergy with Carbon dioxide Capture and Storage (BioCCS) play an ever more crucial role in meeting the 2°C stabilization target. However, such technologies are currently at their infancy and their future penetrations may fall short of the scale required to stabilize the warming. 2) The overshoot in the mid-century prior to a full realization of negative emissions would give rise to a risk because such a temporal but excessive warming above 2°C might amplify itself by strengthening climate-carbon cycle feedbacks. It has not been extensively assessed yet how carbon cycle feedbacks might play out during the overshoot in the context of negative emissions.
This study explores how 2°C stabilization pathways, in particular those which undergo overshoot, can be influenced by carbon cycle feedbacks and asks their climatic and economic consequences. We compute 2°C stabilization emissions scenarios under a cost-effectiveness principle, in which the total abatement costs are minimized such that the global warming is capped at 2°C. We employ a reduced-complexity model, the Aggregated Carbon Cycle, Atmospheric Chemistry, and Climate model (ACC2), which comprises a box model of the global carbon cycle, simple parameterizations of the atmospheric chemistry, and a land-ocean energy balance model. The total abatement costs are estimated from the marginal abatement cost functions for CO2, CH4, N2O, and BC.
Our results show that, if carbon cycle feedbacks turn out to be stronger than what is known today, it would incur substantial abatement costs to keep up with the 2°C stabilization goal. Our results also suggest that it would be less expensive in the long run to plan for a 2°C stabilization pathway by considering strong carbon cycle feedbacks because it would cost more if we correct the emission pathway in the mid-century to adjust for unexpectedly large carbon cycle feedbacks during overshoot. Furthermore, our tentative results point to a key policy message: do not rely on negative emissions to achieve the 2°C target. It would make more sense to gear climate mitigation actions toward the stabilization target without betting on negative emissions because negative emissions might create large overshoot in case of strong feedbacks.
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This presentation addresses an important limitation to scientific productivity in fields that rely on computational modeling of landscape processes. Landscape models compute flows of mass, such as water, sediment, glacial ice, volcanic material, or landslide debris, across a gridded terrain surface. Science and engineering applications of these models range from short-term flood forecasting to long-term landform evolution. At present, software development behind these models is highly compartmentalized and idiosyncratic, despite the strong similarity in core algorithms and data structures between otherwise diverse models.
We report progress on a proof-of-concept study in which an existing landscape model code is adapted and enhanced to provide a set of independent, interoperable components (written initially in C++). These include: (1) a gridding engine to handle both regular and unstructured meshes, (2) an interface for space-time rainfall input, (3) a surface hydrology component, (4) an erosion-deposition component, (5) a vegetation component and (6) a simulation driver. The components can communicate with each other in one of two ways: using a simple C++ driver script, or using the Community Surface Dynamics Modeling System (CSDMS) Model Coupling Framework.
A central element is the gridding engine, which provides the ability to rapidly instantiate and configure a 2D simulation grid. Initially, the grid is an unstructured Delaunay/Voronoi mesh. Because the internal representation of geometry and topology is quite generic—consisting of nodes (cells), directed edges, polygon faces, etc.—the software can be enhanced to provide other grid formats, such as a simple raster or a quad-tree representation. The gridding engine also provides basic capabilities for finite-volume numerics, such as calculation of scalar gradients between pairs of neighboring cells, and calculation of flux divergence within cells.
Our hope is that these interoperable and interchangeable components with simple, standardized interfaces, will transform the nature and speed of progress in the landscape sciences by allowing scientist-programmers to focus on the processes of interest rather than on the underlying software infrastructure.
This presentation discusses the implementation of component-based software design in Eco-hydrologic modeling. As a first step, we present development and integration of a radiation component that uses the local topographic variables to compute shortwave and longwave radiation data over a complex terrain for modeling Eco-hydrologic dynamics. This component is integrated to a central element that develops and maintains a grid, which represents the landscape under consideration. This component communicates with various other components such as ‘vegetation component’ and ‘soil moisture component’. This component is adapted from the Channel-Hillslope Integrated Landscape Development (CHILD) Model code and has been enhanced. Preliminary results of this study demonstrate the advantages of adopting component-based software design such as improved flexibility, interchangeability and adaptability. +
This presentation or poster will discuss the latest developments of the CUAHSI Hydrologic Information System including 1) the new open source server components built using PHP and MySQL specifically to support citizen science; and 2) the desktop application HydroDesktop with its extensions for search and discovery of data on the 100 servers of the CUAHSI data network. The presentation or poster will include a discussion of the potential integration of HIS data sources in CSDMS modeling efforts and potential for integration of the CSDMS modeling architecture with the HydroDesktop client application. +
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.
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This study aims to fundamentally assess the impact of sea level rise (SLR) on vegetated, muddy coastlines. This includes an assessment of the resilience of coupled salt marsh-mudflat and mangrove fringe-mudflat coastlines under different sea level rise scenarios.
Traditionally, the design of coastal protection measures revolved around the use of hard structures to ensure a certain level of design safety against flooding of the coastal hinterland. However, with the effects of climate change: sea level rise, increased intensities and frequencies of storms; these solutions appear to be unsustainable. Building-with-Nature strategies have reinforced the value of vegetated foreshores, as being capable of allowing for a flexible and adaptive response to climate change. They attenuate wave energy, stabilize and may heighten the foreshore at a rate that matches that of sea level rise. Important parameters related to the resilience of vegetated foreshores to sea level rise are site specific and include sediment supply, wave climate, tidal range, sea level rise rates, type of vegetation cover, vegetation dynamics and topography.
Process-based numerical modelling tools are critical towards enhancing the understanding of the processes governing the morphological development of vegetated-mudflat systems. Limited studies have quantified the impact of sea level rise on the resilience of these intertidal systems with a key focus on determining the tipping points and the governing processes for bio-geomorphological development. Therefore, we applied an open-source 2D process-based model (Delft3D) that couples intertidal flow, wave-action, sediment transport, morphodynamic development with the vegetation dynamics for temporal and spatial growth and decay of vegetation and bio-accumulation.
The vegetation growth model was developed using MATLAB, which was then coupled with a depth averaged Delft3D model. For the salt marsh species, the growth model was based on that of a population dynamics approach whereas the mangrove growth model was based on a windows of opportunity approach. The model setup was inspired by conditions within the Dutch South Western Scheldt and the Guyana coastline for the salt marshes and mangroves respectively. The numerical model and the coupling approach were validated quantitatively against existing theory, data and laboratory studies; after which the system’s resilience against sea level rise was examined.
Spatial equilibrium of the marsh-mudflat system was attained within 120 years with wave action and sediment dynamics being key triggers. The mangrove fringe-mudflat model however attains equilibrium on longer timescales. The subsequent imposition of a 100 year period of rising sea-level (1.1m) in salt marsh-mudflat systems revealed the biomass accumulation as a critical determinant for the drowning rate. Though, initially highly resilient against the exponential increase of sea level rise, the marsh system starts to drown as channels incise the platform after 50-60 years. This corroborates recent studies which predict a decline in the carbon sequestration potential of salt marshes within the North Sea. Contrastingly, the mangrove fringe-mudflat system proved resilient after a 100 year period of extreme SLR and the increases in drag gained from their extensive mangrove root network and the below ground biomass accumulation proved to be the main drivers. However, after 150 years, there is a shift in the nature of the system as it starts to drown. Results show survival for both systems in sediment rich areas. Overall, the model can be applied to assess the vulnerability and resilience of vegetated coastal areas impacted by sea-level-rise worldwide. Thereby, proving to be a useful tool for developing countries where data is scare. Both the Delft3D software and MATLAB tools used in this study are open source and freely available online: https://oss.deltares.nl/web/delft3d. The running of the model requires the use of MATLAB versions 2013 or higher. This software can be attained through purchase, student version or trial online: https://nl.mathworks.com/products/matlab.html. With regards to the hardware required, a standard PC with minimum 8GB RAM. Additionally, the MATLAB source code will be made available via the Environmental Modelling and Software Journal (ESM) once published.
This study investigates riverine sediment dispersal within a bedrock confined estuary in British Columbia, Canada using the HydroTrend and Sedflux models. The models are evaluated using multibeam and acoustic backscatter surveys, piston cores, and grab samples across the Skeena Estuary and its contiguous marine areas. The data has been compiled to produce an overview of seabed geomorphology, texture, and sedimentation rates in the estuary and marine approaches. The model HydroTrend was used to estimate incoming sediment load from the Skeena River. Model estimates of suspended sediment load are higher than past estimates due to a large contribution of suspended sediment from a portion of the Skeena watershed previously excluded due to a lack of available hydrographic data. Over thirty kilometres from the river mouth, cores recovered mud sequences in the deeper proximal bedrock confined channels that indicated sedimentation rates of up to 2.83 cm yr-1. These deeper estuarine passages are seaward of the sandy deposits that make up the delta platform. In comparison, sedimentation rates in the further offshore marine approaches to the Skeena Estuary are as low as 0.004 cm/yr. Sedimentation rates within the estuary agree with the SedFlux model outputs using the HydroTrend sediment load results. More specifically, a sedimentation rate of 2.9 cm/yr was predicted using the SedFlux model at the same distance from the river mouth as the mud sequence radiocarbon dated cores. A relatively high sedimentation rate and seaward fining trend in grain size are interpreted as indicators of high riverine input to the seabed regionally. This initial evaluation of model performance encourages further examination of sedimentation conditions in the Skeena Estuary, including those of importance to eelgrass beds and major port development areas. +
