Property:CSDMS meeting abstract
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Launched in December 2022, the Surface Water and Ocean Topography (SWOT) Mission houses a first-of-its-kind satellite instrument, KaRin, with an interferometric Ka-band active radar and a near-nadir look angle. Most importantly, SWOT's KaRin instrument measures coincident water surface elevation and widths, and over a large 120 km swath every 10 days on average, enabling estimation of volume change in static waterbodies and discharge in rivers. SWOT measures 0.5% earth’s surface area per hour and offers stunning new insights into ocean and inland waterbodies. Less well known are SWOT’s capabilities for rivers, particularly rivers that are otherwise difficult to sample with field equipment. Using SWOT and field data, this presentation will discuss the hydraulic and geomorphic implications of one year of SWOT measurements, including data from rivers in Western North America. +
Like many densely populated deltas worldwide, the Ganges-Brahmaputra Delta faces cascading flood and salinization hazards associated with relative sea-level rise (RSLR). One of the greatest uncertainties in future RSLR projections stems from the compaction of unconsolidated sediments, which causes land to subside with significant spatiotemporal variations. Here we constrain compaction variations on the Ganges Brahmaputra Delta, using a state-of-the-art 1D compaction model based upon fundamental principles of porous-media mechanics and groundwater flow; as well as constitutive relations for porosity and edaphic factors (e.g., roots, burrows). The model accurately reproduces field observations from GNSS, RSET-MH, and optical fiber strainmeters with compaction-induced subsidence rates of 1–30 mm/y depending upon local thickness and lithology of underlying Holocene deposits, forest tree density, and sedimentation rate. Sedimentation drives a dynamic compaction response over timescales of 10–100 years, such that floodplains cut off from sediment after 1950’s embankment construction have undergone significant elevation loss and are now experiencing a gradual subsidence slowdown. Updated RSLR projections informed by our model indicate that compaction-induced subsidence will be responsible for up to 50% of twenty-first-century RSLR, and exert a first-order control on hotspots of flooding and salinization hazards. +
Long-term tectonics shape the landscape we live on. Collision over 10s of millions of years has produced the Himalayan mountain chain, the Tibetan Plateau and the atmospheric disturbance that produces the Asian monsoon. But it is the dynamic, short-term manifestations of tectonics and plate boundaries and their aftermath that most dramatically impact people’s lives. The shaking of a large main shock, while overwhelming, is over within minutes but the consequences of the shaking on the landscape can last for years to decades. In particular, in mountainous environments, a sedimentary hazard cascade (SHC) can dominate a region in the decades following a large earthquake. The 1999 Chi-Chi earthquake in Taiwan, the 2008 Wenchuan earthquake in China and most recently the 2016 Kaikioura earthquake in New Zealand provide the opportunity to quantify and model some of these impacts. In particular, improved knowledge of spatial and temporal variations in rock erodibility help us to understand the physical connections between tectonic structure and the Earth surface, both in the short and in the long term. Quantifying rock damage (erodibility) as a result of tectonic processes is an important step in exploring the link between the processes that occur on the timescales of the human dimension and long term tectonics. +
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Low-lying coastal barriers face an uncertain future over the next century, with many projections suggesting end-of-century rates of sea-level rise as high as 1 cm/yr. The hazards associated with this passive inundation can be reasonably estimated using state-of-the-art tools. However, the coast is not a bathtub - increased sea levels enhance the ability for waves to reorganize the coast, typically resulting in increased shoreline retreat by moving sediment either offshore into deeper waters or onshore by overwashing the existing coast.
Although many models of coastal change have been developed, the majority are either highly calibrated and intended to operate at the temporal scales of engineering projects (< ~5 years), offering little possibility of forecasting never-seen behaviors such as barrier drowning, or long-term geologic models, which typically assume that the coast maintains an ‘equilibrium’ configuration that moves with sea level. We aim at bridging the gap between these approaches by constructing a simple model that focuses on dynamical coupling of two primary barrier components: the marine domain represented by the active shoreface, which is constantly affected by transport and reworking by waves, and the backbarrier system, where the infrequent process of overwash controls landward mass fluxes. The model demonstrates that coastal barriers can respond to an accelerated sea-level rise in complex, less predictable manners than suggested by existing conceptual and long-term numerical models. Model behaviors under constant sea-level rise reveal two potential modes of barrier failure: ‘height drowning’, which occurs when overwash fluxes are insufficient to maintain the landward migration rate required to keep in pace with sea-level rise; and ‘width drowning’, which occurs when the shoreface response is insufficient to maintain the barrier geometry during landward migration. We also identify a mode of discontinuous barrier retreat, where barriers can experience punctuated intervals of rapid rollover and shoreline stability, even with constant rates of sea-level rise. We explore the sensitivity of these modes to external and internal variables, including sea-level rise rate, maximum overwash rate, shoreface response rate, and inland topography.
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Low-lying regions of river deltas (marshes, swamps, and tidal flats) are an important part of the delta life cycle. Marsh sedimentation is characterized by non-riverine, low-bulk density material, and interacts with the riverine sediment delivered by distributary channel networks. These two forms of sedimentation interact to produce the channel properties and kinematics observed in the system. Here, we aim to understand this interaction by comparing two physical delta experiments, one with marsh deposition (treatment) and one without (control). We show that the addition of the marsh proxy (kaolinite) alters the channel properties and kinematics of a river delta. Notably, the channels are longer in the treatment experiment and the shoreline roughness is enhanced. The treatment channels have the same width from the entrance to the shoreline, while the control channels get narrower as they approach the shore. Flow is concentrated in the channels in the treatment experiment, as it has about one-fourth the amount of overbank flow as the control experiment. Interestingly, the channel beds in the treatment experiment often exist below sea level in the aerial portion of the delta top, a phenomena observed in global deltas. However, in the control experiment, the channel beds generally exist above relative sea level. The channels in the treatment experiment have a slope break, on average, which is also seen in some global deltaic rivers (e.g., Mississippi River Delta). The difference in channel properties created by the addition of the marsh proxy in the overbank region helps offset the channel bed aggradation rates in the treatment experiment, as the overbank region aggrades faster (relative to the channel) than in the control. This difference in in-channel and far-field aggradation shows a longer channel in-filling time for the treatment as compared to the control. Although the lateral channel mobility statistics are similar in both experiments, there is more area on the delta top in the treatment experiment that is rarely visited by a channel. This suggests that the marsh proxy may buttress the channels in the treatment experiment. Ultimately, marsh sedimentation on the delta top plays a key role in the channel properties and kinematics of a river delta, producing channels which are more analogous to channels in global river deltas, and which cannot be produced solely by increasing cohesion in an experimental river delta.
Mapping river corridors remains challenging due to the dynamic interactions between water, sediment, and vegetation. Existing land cover maps often misclassify fluvial sediments, limiting their use in river system studies. We present a deep learning framework using incremental learning to refine river corridor mapping by integrating Sentinel-2 imagery with global land cover datasets (ESRI, Google Dynamic World, ESA WorldCover). Our method builds on existing classifications to improve differentiation between fluvial sediment, bare ground, and mining-related disturbances. The results show that incremental learning can enhance river mapping accuracy, providing a customizable approach to better capture riverine landscapes. +
Marine Hydrokinetic (MHK) technologies provide an opportunity to expand renewable energy by harnessing waves and currents power and converting to electricity for residential and commercial application. Locations with rapid tidal flow, large waves, and large tidal range are being considered for implementation of MHK technologies and extraction of energy. However, little is known about the impact of MHK structures on the surrounding ocean morphology. In this study, the hydrodynamic and morphodynamic numerical model, Delft3d, is used to simulate the erosion and deposition around a bed mounted MHK structure to analyze the impacts of seabed slope, sediment grain size, and wave condition on the long-term stability of the device. We analyzed 10, 15, and 20 degree seabed slopes, and three different sediment grain sizes representing fine, medium, and coarse-grained sand. For wave conditions, we ran storm condition of the frequent 1-2 year recurring storm in North Carolina Coast, which occurred during Hurricane Mathew in 2016. We also tested the mean wave conditions and the extreme 100-year storm for the same location. Our initial results suggest that steeper sloped beds, finer sediment grains, and larger wave heights will be more problematic for increasing total deposition and burial of bed-mounted MHK devices. However, depending on the type of MHK device, this impact may not be as important as potential scour around the MHK leading to toppling and failure of the device. Moreover, for extreme storm conditions (i.e. the 100 year storm), scour and potential collapse of the foundation or anchor of the bed-mounted MHK may be a serious concern. +
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Marine carbonates are created by the metabolism, growth, death and skeletal accumulations of a diverse array of benthic organisms (e.g. corals, bryozoa, molluscs, foraminifera, calcareous algae, and micro-organisms), but carbonate accretion requires a positive net balance among biological growth processes, processes of biological erosion (mainly by fishes, urchins, polychaetes, molluscs, sponges, algae and micro-organisms), and physical processes of destruction, suspension, transport, deposition and cementation. We are creating a knowledge base (KB) containing empirical quantitative data about individual, population and community properties of major calcifying and bio-eroding species to capture the ecological variation inherent in all biological processes, both spatial (e.g. latitude, longitude, habitat, climate, oceanography, depth) and temporal (e.g. diurnal, seasonal, interannual). The KB will provide realistic values for input to a “virtual aquarium” of characteristic organisms at the center of biologically-based carbonate models describing the initiation, growth and maturation through ecological to geological timescales of such formations as shallow and deep-sea coral reefs, Halimeda beds, bryozoan reefs, and maerl deposits. +
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Marshes are highly dynamic landscapes that are shaped through feedbacks between hydrodynamic, morphodynamic, and ecological processes. Future marsh resilience is therefore dependent on the interaction between these different drivers rather than any individual piece. Marshes face a variety of threats, both natural and anthropogenic, resulting in a need for restoration actions that increase survivability. Because many of these threats are unprecedented or acting at unprecedented rates, statistical models do not adequately represent future conditions and require process-based models to better capture the complex interactions between both physical and ecological processes. The comprehensive marsh model integrates tidal flow, morphodynamics, and vegetation growth using the python based Landlab toolkit. This model is then applied at a site within the Seven Mile Island Innovation Laboratory complex in coastal New Jersey. +
Migration is a complex phenomenon that is impacted by economic, social, cultural, and environmental factors. This complexity makes it challenging to study, and especially challenging to understand how future environmental and climatic change may affect mobility and population movements. Agent-based modeling (ABM) is a promising but underutilized method for studying environmental impacts on human migration because of its ability to study connections between large-scale dynamics and individual decision-making. This work presents initial results from an original ABM that simulates household migration decisions in Bangladesh under environmental pressure. The model seeks to understand how riverbank erosion and land inundation impact mobility patterns under varying decision-making frameworks and livelihood opportunities. The model stochastically simulates inundation of land bordering a river. Agents whose land is flooded seek employment in a local labor market. Agents who cannot find employment within the community then face the decision to migrate or remain in the community with limited economic opportunity. We compare several different decision frameworks of varying complexity, in which the probability of choosing to migrate depends upon: household wealth alone, wealth, age, and household size, and finally using the Theory of Planned Behavior, which incorporates interactions between individual-level variables and community-level phenomenon, such as social norms, which are mediated through each agent’s social network. This model serves as a starting point to begin to test how different decision-making frameworks and environmental scenarios may produce different dynamics in the response to environmental stress. +
Minnesota’s drainage-ditch network facilitates agriculture by draining standing water, but disrupts hydrological connectivity and the water extent of wetlands. These wetlands are critical for ecosystem health, water filtration, carbon storage, and flood protection (e.g. Hansen et al. 2018, Office of Water 2002). Cowdery et al. (2019) investigated a case study of wetland restoration in western Minnesota, but the study region experienced variable precipitation and environmental factors across pre- and post-restoration periods. In our project, we systematically model drainage-ditch removal and wetland restoration across all Minnesota watersheds. Using computational GIS, we develop a topobathy digital elevation model, which accounts for depressions that currently store water. We run depression-filling algorithms (Barnes 2016, Barnes et al. 2020, Barnes et al. 2021) to first compute water storage in the current landscape. With information on current water storage in hand, we digitally infill drainage ditches and recalculate water storage and extent. These results will isolate the impacts of certain drainage ditches on surface water.
* Barnes, Richard. 2016. RichDEM: Terrain Analysis Software. http://github.com/r-barnes/richdem
* Barnes, R., Callaghan, K. L., & Wickert, A. D. Computing water flow through complex landscapes – Part 2: Finding hierarchies in depressions and morphological segmentations, Earth Surface Dynamics, 8, 431–445, https://doi.org/10.5194/esurf-8-431-2020, 2020.
* Barnes, R., Callaghan, K. L., & Wickert, A. D. Computing water flow through complex landscapes – Part 3: Fill–Spill–Merge: flow routing in depression hierarchies. Earth Surface Dynamics, 9, 105-121, https://doi.org/10.5194/esurf-9-105-2021, 2021.
* Cowdery, T., Christenson, C. A., Ziegeweid, J. The Hydrologic Benefits of Wetland and Prairie Restoration in Western Minnesota - Lessons Learned at the Glacial Ridge National Wildlife Refuge, 2002-15. U.S. Geological Survey Scientific Investigations Report 2019–5041, https://doi.org/10.3133/sir20195041, 2019.
* Hansen, A. T., Dolph, C. L., Foufoula-Georgiou, E., & Finlay, J. C. Contribution of wetlands to nitrate removal at the watershed scale. Nature Geoscience, 11, 127-132, https://doi.org/10.1038/s41561-017-0056-6, 2018.
* Office of Water & Office of Wetlands, Oceans, and Watersheds. Functions and Values of Wetlands. United States Environmental Protection Agency, EPA 843-F-01-002c March 2002, 2002.
Mixed sediment beaches are common across the globe, yet despite this, they have not been as extensively studied as sandy coasts. In the UK, these gravel-rich ‘shingle’ beaches are used as a first line of defence against flooding, limiting the amount of overtopping on heavily developed coasts such as those found on the South East coast. The shingle beach at Pevensey Bay, in East Sussex is the UK’s largest natural flood defence and is maintained through publicly funded, long-term beach management activities, recharge, recycling and by-passing of material. Monthly beach surveys, carried out to inform these works, revealed that the foreshore was experiencing chronic erosion with the loss of approximately 8,000 m3 of sediment each year. Whilst changes to the upper beach are constantly tracked and managed changes occurring just below the waterline were practically unknown.
Identifying the pathways for sediment movement across the nearshore zone was a key objective for this study to help understand the continued erosion of the foreshore. Analysis of multibeam bathymetry and X-Band radar reflectance data revealed the presence of transverse finger bars in the nearshore zone. The bars extended up to 700m offshore and were approximately 80-120m wide, with a maximum amplitude of 0.5m. Weekly-averaged reflectance imagery showed the position of the bars, which are orientated at 45o to the coastline, as the surface roughness of the sea was moderated by the seabed. These high temporal frequency roughness signatures showed that the bars were permanent features on the seabed and that they were migrating at a rate of approximately one wavelength a year. The movement of the bars was triggered by excess wave energy; peak migration rates were reached in the 2020 November to December period, whilst virtually no movement occurred between April and September 2021. Similar spatio-temporal patterns have been observed in erosive and accretive pulses in the upper beach and the link between bar movement and beach response is examined. Gaining a clearer understanding of the movement of sediment within the nearshore zone on beaches such as Pevensey will improve our understanding of how mixed sediment beaches function and brings into question whether active upper beach management is the most sustainable long-term option
Models of bedrock river incision, whether stream-power or mechanistically based, incorporate approximations of bedrock susceptibility to erosion. One or more parameters for a specific basin, lithology or outcrop may be estimated, and related to erodibility, as well as abrasion and plucking characteristics. However, choosing those parameters requires information of bedrock properties, which are either approximated or measured. Field and flume measurements are currently used to obtain physical bedrock properties that can be used for those models. Most studies focus on either field or flume measurements, but it is unclear whether their results are interchangeable. Therefore, we compare field measurements of compressive strength obtained with the Schmidt hammer and fracture intensity and block size with macro-abrasion and attrition rates obtained by flume measurements. We aim to discuss their possible meaning in terms of physical erosion processes and their use for bedrock river incision modeling. +
Models of coastal barrier ecomorphodynamic change are valuable tools for understanding and predicting when, where, and how barriers evolve, which can inform decision-making and hazard mitigation. Present ecomorphodynamic models of barrier systems, however, tend to operate over spatiotemporal scales incongruous with effective management practices (i.e., too fine-scale/event-based or too coarse/long-term). In contrast, we are developing a new model capable of simulating ecomorphologic change of undeveloped barrier systems over several kilometers and decades with a 1-by-1 m planform grid and weekly time step. The model couples aeolian dune growth and vegetation dynamics (DUBEVEG), storm erosion of the beach and foredunes (CDM/SBEACH), storm overwash (Barrier3D), and shoreline/shoreface adjustment (LTA14). We parameterize the model with elevation and vegetation data from North Core Banks, NC, focusing on changes caused by Hurricane Florence (2018). Calibrating free parameters using a genetic algorithm, we find good to excellent agreement with observed and simulated elevation change for representative, small (<1 km alongshore) barrier segments. Future work will include testing the model with multidecadal hindcasts of ecomorphodynamic barrier change; running suites of simulations will allow us to better capture and quantify the probabilistic nature of the dynamic response of barriers to the forces driving coastal evolution. +
Models of landscape evolution provide insight into the geomorphic history of specific field areas, create testable predictions of landform development, demonstrate the consequences of current geomorphic process theory, and spark imagination through hypothetical scenarios. While the last four decades have brought the proliferation of many alternative formulations for the redistribution of mass by Earth surface processes, relatively few studies have systematically compared and tested these alternative equations. We present a new Python package, terrainbento 1.0, that enables multi-model comparison, sensitivity analysis, and calibration of Earth surface process models. terrainbento provides a set of 28 model programs that implement alternative transport laws related to four process elements: hillslope processes, surface-water hydrology, erosion by flowing water, and material properties. The 28 model programs are a systematic subset of the 2048 possible numerical models associated with 11 binary choices. Each binary choice is related to one of these four elements---for example, the use of linear or non-linear hillslope diffusion. terrainbento is an extensible framework: base classes that treat the elements common to all numerical models (such as input/output and boundary conditions) make it possible to create a new numerical model without re-inventing these common methods. terrainbento is built on top of the Landlab framework, such that new Landlab components directly support the creation of new terrainbento model programs. terrainbento is fully documented, has 100% unit test coverage including numerical comparison with analytical solutions for process models, and continuous integration testing. We support future users and developers with introductory Jupyter notebooks and a template for creating new terrainbento model programs. In this paper, we describe the package structure, process theory, and software implementation of terrainbento. Finally, we illustrate the utility of terrainbento with a benchmark example highlighting the differences in steady-state topography between five different numerical models.
Monitoring of subsurface contaminants by N3B Los Alamos, indicates new locations of contaminant leakage below Material Disposal Area L (MDA L) at Los Alamos National Laboratory (LANL). The spread of legacy waste poses a concern of volatile organic compounds (VOCs) reaching the regional groundwater. The purpose of this work is to locate and quantify leak sources at MDA L and estimate the effect of contaminant removal periods on the plume using the LANL-developed finite volume multiphase simulator (FEHM) for gas transport modeling. The most prevalent contaminant in the plume is 1, 1, 1,- trichloroethane (TCA) and this species is used as a tracer to track plume movement in the model. The grid resolution is 10m horizontally and ranges from 1m to 25m vertically, with the higher resolution close to the surface. The model domain is set to LANL atmospheric pressure, constant temperature of 15C, and constant relative permeability set to 0 and 1 (-) for liquid and vapor, respectively. This work simulates saturation-dependent vapor diffusion of TCA via an isothermal two-phase (air-water) process. Over 140,000 nodes set the initial and boundary conditions related to pressure, saturation, and flow data (source/sink parameters). Readjustment of TCA concentrations will take place from November 30, 2016, to May 25, 2023 within the model. Soil vapor extraction (SVE) measurement periods at MDA L will be reflected in the simulations. Post-simulations, short-term SVE will be simulated to compare against SVE data from May 2024. +
Moraines in marine-terminating outlet glacier settings can provide a feedback mechanism for glacier stability or retreat, however, sedimentation dynamics in Greenland are poorly understood. With limited observations, sedimentation contributes to the large uncertainty of ice dynamics in estimating Greenland’s future sea level potential. Recent attempts to couple ice and sedimentation show the importance to include moraine-building processes. To advance our understanding, it is necessary to quantify the impact of sedimentation in Greenland outlet glacier settings on different timescales. We explore the sensitivity of Greenland outlet glaciers to sedimentation dynamics including sediment diffusion (removing sediment from moraines) and glaciofluvial sedimentation (adding sediment to moraines) in a flowline model adapted from Brinkerhoff et al., 2017. We run an ensemble of simulations to investigate these processes on 20 kyr timescales, using different bed topography slopes, surface mass balance scenarios, and with sedimentation coupling turned on versus off. We compare across simulations with parameters like ice volume, sediment volume, ice velocity, and bed topography profiles. We find that sedimentation has a strong control on ice volume change and creates tide water glacier cycles with changes in amplitude over time. In addition, we determine the sensitivity of the tide water glacier cycle to variations in bed topography and surface mass balance. The coupling between sediment and ice dynamics could explain and contribute to the divergent glacier behavior presently seen in Greenland outlet glaciers. This work is important for ice sheet model development and field work efforts to understand the rates and processes driving sedimentation in Greenland. +
Morphological patterns reflect climatic and geomorphic influences throughout a dunefield’s history and can thus be a valuable source for information about past and present environmental conditions. The quantitative assessment and interpretation of such patterns requires precise information about dune locations and arrangements, i.e., dune maps. Mapping dunes based on satellite data has evolved from a simple tool for dryland research to a notable research area. Globally available datasets and the progression of computational infrastructure have facilitated the operation of increasingly elaborate automated algorithms to map spatially extensive areas where manual approaches would be inefficient.
We present a deep learning framework that employs semantic segmentation techniques on optical satellite imagery and medium resolution digital elevation models to map linear dunefields. The workflow includes the access and pre-processing of training and prediction data, with a Neural Network as the centrepiece that is trained and applied to identify dune crests. We conducted a preliminary case study to develop and evaluate the framework on the dunefields of the Kalahari Desert, producing promising results.
Our next step is to leverage the generated dune maps to classify different dune patterns and investigate their relationship with climate and topography. We hope to provide valuable insights into the complex interplay between dunefield morphology and its environmental and climatic drivers. +
Most of the estuaries and lagoons around the globe are unique and have distinct but irregular shorelines and bathymetries and normally surround by highly developed watersheds with expanding agriculture and urbanization in mid and low latitudes. It is important to understand influence of environmental perturbations on the local coastal ecosystems. This project aims to develop a model for water quality and phytoplankton dynamics in the Maryland Coastal Bays during various physical conditions and to provide a prototype to other global estuaries and lagoons. The preliminary results indicated that model was able to well capture the observed seasonal chlorophyll-a and nutrients distribution patterns; and the weak discrepancy in vertical distributions of phytoplankton was mainly caused by dominated wind and tidal mixing effect in the shallow of water column. The research outputs will link modeling with local policymakers for ecological restoration and harmful algal bloom prevention by optimizing the amount of nutrient reduction in freshwater inflow to restore the ecosystem and making timely predictions of harmful algal blooms under different weather conditions. The estimation and discussion towards the spatial and temporal variabilities of phytoplankton distribution under extreme weathers will provide reference for ecological studies in MCBs and other similar lagoon systems around the world. +
Much of modern tectonic geomorphology focuses on interpreting patterns of bedrock river slope and using this information to make tectonic inferences. At its core, this framework often assumes that rivers are readily able to erode bedrock, and that they respond to tectonic and climatic forcing mostly through vertical incision and slope adjustment. However, bedrock rivers must also transport sediment delivered to them by surrounding hillslopes, which may act to amplify or to inhibit incision into bedrock. Rivers also adjust their width in response to climatic and tectonic controls, often much faster than slope adjustments can occur. While the importance of sediment flux and channel width has been understood for some time, these behaviors are hard to predict mechanistically and thus go unaccounted for in many models of landscape evolution. We present a model of river evolution in which channel slope and width freely evolve to optimize sediment transport and bedrock incision in response to stochastic water and sediment discharge. We investigate the impact of both water and sediment discharge variability under varied tectonic forcing and find that equilibrium channel form is controlled by a combination of water and sediment supply variability. We use the model to document measurement biases in rates of river incision (the Sadler effect) which are observed ubiquitously in real landscapes, and to for the first time examine the drivers of variations in this effect. Our results call into question the assumptions underlying the widely used detachment-limited stream power incision model of river evolution and highlight the importance of considering channel width and sediment flux when modeling river behavior and measuring rates of erosion over landscape evolution timescales. +
