Property:CSDMS meeting abstract
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Chronic coastal flooding, or flooding that occurs outside of extreme storm events, can impact a community’s ability to access homes, businesses, roads, and/or other necessary infrastructure. The drivers of chronic coastal flooding can be highly local, making it difficult to predict the full spatial and temporal extent of flooding. In our poster we introduce an easily maintainable camera system that we have developed to monitor flooding in coastal regions. Our device - a Tiny Camera with Machine Learning, or TinyCamML - is a small, solar-powered, low- cost (<$400), microcontroller-based camera that uses on-device machine learning to classify images (taken every 6 minutes) as “Flooded” or “Not Flooded.” TinyCamMLs transmit – in real-time via cellular network - only the classifications to a website, providing situation awareness during flood events. Images are never transmitted (and can be set up to not even be saved), protecting the privacy of the local communities in which they are deployed. We provide information on the device, developing the (quantized) ML model, and show results from our test deployments in North Carolina. The camera system could easily be adapted to host other ML models designed to capture or measure various Earth surface processes. +
Climate change and reduced water availability in arid regions has important implications for how channels will change as they adjust to a new steady-state characterized by different riparian populations. While much study has been devoted to the effects riparian vegetation has on fluvial processes (Tal & Paola, 2010; Osterkamp & Hupp, 2010; Corenblit et al., 2009), the complexity of natural channels obscures exactly how these feedbacks modify long-term channel evolution, making prediction of the larger impacts of vegetation change on channel morphology difficult. In order to isolate the impact vegetation has on morphology, single channels that are variably vegetated along their length are desirable for study because flow conditions and long-term sediment flux change minimally between major tributaries (Bertoldi et al., 2011). Comparisons made in such dryland channels in Henry Mountains, Utah, USA, where groundwater springs juxtapose vegetated and un-vegetated reaches allow us to examine two hypotheses: first, that disruptions to normal fluvial processes caused by in-channel vegetation produce distinct morphological responses to floods at the scale of single flood events, and, second, that these responses accumulate on the timescale of multiple floods to produce channel morphologies in vegetated reaches that are fundamentally different from those in unvegetated reaches. Analysis of repeat airborne LiDAR data for these areas provides an opportunity to quantify morphological parameters and elevation differences, and to attempt to correlate these metrics with quantitative metrics of vegetation. Field observations from October, 2017 in this region agree with the results of LiDAR analyses and indicate that the presence of dense vegetation seems to produce more uniform cross-sectional shape with narrow, deeply incised channels supported by intense rooting on banks, and a longitudinal profile that is characterized by frequent vegetation-supported, non-bedrock knickpoints. Future work will involve modelling flood flows to determine the degree and areal extent of channel reworking during a flooding event and the influence of vegetation on shear stress for comparison with LiDAR differencing results.
Climate change has altered the frequency and intensity of hydrologic events like precipitation and flood, yielding vulnerability of communities dwelling in coastal and inland flood plains. Flood prediction and mitigation systems are necessary for improving public safety and community resilience all over the world at Country, continental and global scales. Numerical simulation of flood event has become a very useful and commonly used tool for studying and predicting flood events and susceptibility. One of the major challenges in hydraulic modeling is accurate description of river and floodplain geometries. The increased availability of high-resolution DEMs (e.g. LiDAR data) alleviates this challenge for floodplains but (with the exception of blue/green LiDAR surveys) not for river channels. Here we investigate the effect of river bathymetry data on numerical simulations of flood events. Two numerical models (GSSHA and Mike 21) were used for comparison in the results. Three channel geometry inputs were simulated for three river reaches of different sizes: DEM-captured elevation (water surface), hydraulic geometries (empirical estimation), and observed river bathymetry. +
Climate change has led to unprecedented precipitation events in the hyper-arid Atacama Desert of Northern Chile. On the coast of the El Salado watershed, legacy mine tailings infilled the watershed-ocean connection, while the river channel has been altered both by tailings and urbanization. Loss of life and destruction of infrastructure in a large flood event in 2015 resulted from the coupling of anthropogenic geomorphic changes with unusual climate events. We carry out unsteady two-dimensional simulations fully coupled with the sediment concentration to identify the influence of tailing deposits. The analysis incorporates high-resolution topography data from both pre- and post-flood, where the pre-flood scenario represents the presence of tailings, and the post-flood scenario reflects partial erosion of these deposits. Results highlight the important role of topographic alterations in enhancing the hazard to people and critical infrastructure.
Additionally, an upscaling methodology based on porosity is presented for an urban flood simulation in Santiago de Chile, adjacent to the Andean foothills. In this model, topographic information is included at the subgrid-level to optimize CPU time at the cost of some loss in the accuracy of the results. We analyze how accuracy is affected by gradually increasing grid resolution, specifically when estimating flood extent and associated hazards. Results suggest that the cell size can be increased up to the street width, capturing the main flow paths and hazards while significantly reducing the CPU time employed by classical models.
The integration of an upscaling scheme to model concentrated flows coupled with surface dynamics is particularly valuable for comprehensively assessing flood hazards, meeting real-time decision-making needs. +
Climate change is expected to significantly increase the frequency of severe alpine mass-wasting events, with profound implications for mountainous regions and their downstream ecosystems. Concurrently, there is a rapid growth in urban populations within the lowland areas of the Pacific Northwest, located downstream from these sources. The timing and attenuation of sediment pulse transport can trigger cascading downstream impacts, including heightened flood risks for downstream communities and significant alterations to riverine habitats. This study investigates the contrasting roles of channel characteristics and sediment lithology in shaping downstream sediment transport and associated impacts in rivers with distinct geomorphic attributes: the White River, Suiattle River, and White Salmon River in Washington State, USA. The analysis employs the Network Sediment Transporter (NST), a Lagrangian 1-D morphodynamic modeling framework within Landlab, which simulates the movement and interaction of bed sediment throughout a river network, offering valuable insights into sediment dynamics. The Network Sediment Transporter (NST) models channel reaches as interconnected links within a network grid. Sediments are represented as discrete parcels, each characterized by uniform properties such as grain size, volume, abrasion rate, and particle density, allowing for detailed tracking of their transport and interaction dynamics throughout the river network. We apply the Network Sediment Transporter (NST) to assess the hypothesis that the lithologic characteristics of sediment pulses play a more significant role in shaping downstream channel responses than other commonly considered factors, such as channel geometry or sediment properties. The distinct features of these rivers provide an excellent opportunity to examine how differences in upstream sediment lithology influence downstream impacts. By shedding light on these dynamics, this study aims to improve our understanding of sediment transport processes and support better management of downstream sediment-related challenges.
Climate change is intensifying extreme weather events like wildfires, which increasingly disrupt communities through complex interactions between environmental conditions, infrastructure, and human behavior. This study uses Agent-Based Modeling (ABM) in NetLogo to explore wildfire dynamics as a complex adaptive system, simulating the interplay between fire spread, cascading power outages, and resident evacuation responses. By integrating factors such as infrastructure vulnerability and risk-based decision-making, the model provides insights into system resilience and community outcomes under varied scenarios. +
Climatically controlled surface processes redistribute mass and modulate solid-Earth stress fields, potentially driving changes in tectonics. Examples of climatically-influenced tectonics exist in glaciated orogens, however this phenomenon has not been well documented in fluvial systems. Here we describe a previously undiscussed feedback between hillslope and fluvial processes that buffers climate-tectonic interactions, helping to explain the dearth of observations of climatically influenced tectonics in fluvial systems. Using remote sensing and field investigation, we quantify production, deposition, and transport of landslide sediments resulting from the 2009 Typhoon Morakot in Southern Taiwan, which delivered record-breaking rainfall triggering more than 22,000 landslides across 7800km^2. An annual landslide catalog facilitates use of area-volume scaling to estimate amount of landslide material distributed across a strong northward gradient in tectonic uplift in Southern Taiwan. Landslide volume and frequency exhibit similarly positive trends with distance from the southern tip of the orogen. Exploiting a wealth of publicly available imagery and elevation data, we map sediment aggradation throughout fifteen drainage basins and observe 10’s of meters of aggradation with the distribution tightly coupled to areas of greatest exhumation. Sediment transport modeling across the orogen suggests that areas of highest exhumation will be inundated with sediment over three orders of magnitude longer than less exhumed basins. Estimating the frequency of events like Typhoon Morakot, we expect the most active basins in the study area to have their channels buried by landslide sediment for up to 50% of any given time period, while less active basins will be able to incise nearly 100% of the same time period. This feedback suggests that as landscapes become more exhumed, the erosional buffering effects of extreme storms and earthquakes that cause widespread landslides are amplified, driving a negative feedback between climate driven surface processes and tectonics in fluvial systems.
Close to half a billion people live in deltaic regions worldwide, including in a number of mega-cities. River deltaic landforms act as central locations for agricultural production, livestock farming, and hydrocarbon extraction. The understanding of riverine sediment fluxes and associated delta morphology changes, aids in planning engineering works such as identification of flood-prone areas, installation of coastal defense structures, dam construction, and restoration activities of extensively altered areas.
The overarching goal of the study is to elucidate the interconnectivity between fluvial fluxes and associated landform changes in large global deltas. The following research questions are investigated: (1) Are changes in fluvial sediment flux to the delta directly linked to changes in delta morphology? (2) What are the magnitudes and trends of riverine sediment fluxes that can be expected throughout the 21st century? A multifaceted research approach combining (a) satellite remote sensing analysis of delta morphology changes (progradation/degradation), and (b) numerical modeling of riverine water and sediment fluxes, is used on selected large river deltas globally.
Major outcomes of the study indicate that the synoptic capability of remote sensing provides a useful reconnaissance tool to infer on the rates at which the deltas change. An overview of global delta change is presented with a special focus on case studies with severe degradation and interesting flux estimates. The outcomes of the study yield a number of novel insights into fluvial fluxes of the 21st century and transform our analytical capabilities for studying delta morphology change and sediment flux dynamics in large rivers, globally. +
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Close to half a billion people live on deltas, many of which are threatened by flooding. Delta flooding also imperils valuable ecological wetlands. In order to protect deltas, it is critical to understand the mechanisms of flooding and evaluate the roles of different forcing factors.
Delft3D, a widely used 3D hydrodynamic and sediment transport model, has been applied to the Wax Lake Delta in Louisiana in order to explore the impacts of wind, waves, and vegetation during extreme conditions. Using wind and pressure field inputs of Hurricane Rita in 2005, the simulation indicates that the deltaic hydrodynamics and morphologic changes are determined by the interactions of all three factors. Wind shows a large impact on water level and velocity, especially in the shallow water zone, where water level increases by ~2 m and water velocity increases by ~1 m/s. Waves, on the other hand, demonstrate almost no effect on water level and velocity, but significantly increase sediment transport due to increasing bed shear stress. Sediment deposition occurs primarily at the coast, when water floods higher elevated land and velocities start to decrease, leading to a significant drop in bed shear stress. Vegetation, a critical factor that influences deltaic hydrodynamics, is represented in the model by adding 2D roughness to the bed. The vegetated wetland and its surrounding area show a notably different pattern in erosion and deposition compared to the unvegetated simulations. The vegetated islands receive significant deposition, while adjacent channels become much more eroded because water is routed through channels when the surrounding vegetated islands are more difficult to erode.
To take into account the impact plant roots have on the soil (increase in soil strength and therefore an effectively reduction in erosion), a new root routine has been added to Delft3D. This routine mimics this process by increasing the soil critical shear stress required to reduce erosion. The modeled results indicate that more deposition appears on the vegetated root area, while more significant erosion simultaneously occurs at those sides of these islands that are facing the ocean. This illustrates that, while vegetation can protect land from erosion, it can also intensify erosion in the surrounding area. Therefore, the use of natural vegetation as a protection against coastal erosion processes requires more research.
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Coastal aquifers, vital freshwater sources for over a billion people globally, often face saltwater intrusion, especially in island freshwater lenses. Despite extensive studies on sea-level rise, storm surges, and over-pumping, the impact of droughts on coastal aquifers, particularly barrier island aquifers reliant solely on aerial recharge, remains understudied. Understanding recharge and salinization processes is crucial for sustainable water resource management amid potential climate change impacts. This study introduces a novel approach to assess a freshwater lens's response to drought conditions, incorporating in-situ observations, geophysical measurements, and numerical modeling. Examining a Northeastern U.S. barrier island's shallow unconfined aquifer during the 2020 drought, the research reveals a reduction in the freshwater lens volume during reduced recharge, emphasizing the vulnerability to droughts and the potential for recovery. Comprehensive studies in this area are essential for informed water resource management. +
Coastal areas globally face increasing threats from intensified weather events and rising sea levels, leading to challenges such as fluctuations in groundwater levels and salinity intrusions. This presents a significant concern for the Department of Defense (DoD), which manages over 1700 coastal sites worldwide, with several facing heightened vulnerability to these environmental changes. We aim to evaluate the susceptibility of DoD coastal sites to sea-level rise and saltwater intrusion, utilizing the Defense Regional Sea Level (DRSL) database that includes projections for five global sea-level rise scenarios and extreme water events. To achieve this, we have adopted a two-pronged strategy. First, we conduct an in-depth vulnerability analysis considering the current situation, sea-level trends, and topographic elevation. The vulnerability analysis aids in selecting sites for detailed further investigation. Subsequently, we formulate Reduced Order Models (ROMs), including Dynamic Mode Decomposition (DMD) and the Unified Fourier Neural Operator (U-FNO) for sites with a range of vulnerabilities. DMD and U-FNO are selected for their efficiency, enabling faster execution and thousands of runs to assess site vulnerability under future climate scenarios through the century's end. Trained on site-specific mechanistic models, both DMD and U-FNO accurately simulate current groundwater and salinity conditions, providing reliable forecasts of future impacts on DoD sites, utilizing data from the DRSL database and climate model projections. This approach clarifies the immediate risks and facilitates the transfer of essential knowledge throughout DoD's extensive network, fostering a deep understanding of global coastal vulnerabilities. Ultimately, this informs the development of targeted, effective mitigation strategies, safeguarding critical defense infrastructure against the impacts of climate change. +
Coastal communities facing erosion require beach maintenance for property protection and recreation. While some communities may have the means to pay for sand nourishment, others may benefit from their neighbor’s alongshore-transported sediments. If communities expect to free-ride off beach nourishment carried out by a neighbor, incentives favoring inaction may lead to narrower beaches overall. Recent work coupling human and natural systems found that coordination between neighboring communities is preferable economically to each community acting independently. Contrasting past work, we model two communities acting without knowledge of a jointly determined economically optimal nourishment program. Instead, nourishment behavior is triggered by a traditionally imposed minimum beach threshold and bounded by a predefined seaward edge. The goal is not to limit sand loss; rather, nourishment decisions are based on separate or joint benefit-cost assessments for two communities. We compare two management approaches: (1) sequential/decentralized decisions, where the updrift community chooses first and the downdrift community reacts second; and (2) simultaneous/coordinated decisions where both communities make a joint choice. We test how variable up/downdrift property values affect outcomes under these two approaches. Results suggest that communities do not always favor coordinating simultaneously. When both up- and downdrift communities have high property values, sequential/decentralized decisions are favored, leading to updrift over-nourishment to maintain beach width. This enhances alongshore sediment availability, thus providing higher marginal benefits for downdrift communities whom under-nourish. When the property values of the updrift community are low and the property values of the downdrift community are high, however, the outcome results in abandonment of property by the updrift community instead of coordinating with the downdrift community. Overall, we find that the distribution of property values across neighboring communities can be a driver for both strategy selection and the decision-making process.
Coastal ecosystems, infrastructure, and human health are vulnerable to extreme precipitation, flooding, and water-quality impacts. Integrating a hydrologic model (WRF-Hydro) into the Coupled Ocean Atmosphere Wave Sediment Transport modeling system (COAWST), which includes ocean (ROMS), atmosphere (WRF), surface-wave (SWAN, WAVEWATCHIII), sediment (CSTMS), and sea-ice components, offers the potential to investigate compound flooding and the dispersal of contaminants, sediments, and other material at the land-ocean boundary. Here, the new model coupling is described, along with an application to Hurricane Florence.
Extreme precipitation during Hurricane Florence, which made landfall in North Carolina in September, 2018, led to breaches of hog-waste lagoons, coal-ash pits, and wastewater facilities. In the weeks following the storm, historic freshwater discharge carrying pollutants, sediment, organic matter, and other debris was released to the coastal ocean, contributing to beach closures, algal blooms, hypoxic conditions, and other ecosystem impacts. The Cape Fear river basin, North Carolina’s largest watershed, is used as a case study. Progress in model coupling applied to this region includes (1) a two-way coupled ROMS and WRF-Hydro simulation in which fluxes between the ocean and hydrology models are computed from the pressure gradient at the ocean-land boundary, and (2) a one-way coupled simulation in which a WRF-Hydro simulation provides river point-source forcing in ROMS. The work as part of the one-way coupled simulation demonstrates how the pathways of land-sourced tracers can be tracked in the coastal ocean; a suite of different flood and wind scenarios are studied and used to map the arrival and departure times of threshold-exceeding contaminants that contribute to swimming advisories and other impacts. Next steps are described for continuing the ocean-hydrology model coupling efforts to improve forecasts of compound flooding and water quality impacts.
Coastal erosion and wetland loss are affecting Louisiana to such an extent that the loss of land between 1932 and 2016 was close to 5,000 km2. To mitigate this decline, coastal protection and restoration projects are being planned and implemented by the State of Louisiana, United States. The Louisiana Coastal Master Plan (CMP) is an adaptive management approach that provides a suite of projects that are predicted to build or maintain land and protect coastal communities. Restoring the coast with this 50-year large-scale restoration and risk reduction plan has the potential to change the biomass and distribution of economically and ecologically important fisheries species in this region. However, not restoring the coast may have negative impacts on these species due to the loss of habitat. This research uses an ecosystem model to evaluate the effects of plan implementation versus a future without action (FWOA) on the biomass and distribution of fisheries species in the estuaries over 50 years of model simulations. By simulating effects using a spatially-explicit ecosystem model, not only can the changes in biomass in response to plan implementation be evaluated, but also the distribution of species in response to the planned restoration and risk reduction projects. Simulations are performed under two relative sea level rise (SLR) scenarios to understand the effects of climate change on project performance and subsequent fisheries species biomass and distribution. Simulation output of eight economically
important fisheries species shows that the plan mostly results in increases in species biomass, but that the outcomes are species-specific and basin-specific. The SLR scenario highly affects the amount of wetland habitat maintained after 50 years (with higher levels of wetland loss under increased SLR) and, subsequently, the biomass of species depending on that habitat. Species distribution results can be used to identify expected changes for specific species on a regional basis. By making this type of information available to resource managers, precautionary measures of ecosystem management and adaptation can be implemented.
Coastal flooding is an increasingly prominent hazard in the northeast United States, causing both property damage and disruption of daily life. Tide gauge records provide historical water level data and are used to estimate current return periods of storm tides (tide level plus storm surge) from both hurricanes and nor’easters. We calculate the interannual joint probability exceedance curves for select tide gauges in the Philadelphia, New Jersey, and New York City megaregion using the quasi‐nonstationary skew surge joint probability method (qn‐SSJPM) from Baranes et al. (2020). Analysis of the probability of storm tides for hurricane versus nor’easter seasons will be discussed, including geographic variations of the storm tide exceedance curves. Results from this study can be compared to storm climatology and used by social scientists and city planners to assess risk associated with the flood hazard in the area. By understanding the ways that probability of storm tide in summer and winter may change in the future, communities can better plan and prepare for future hazards. +
Coastal foredunes are dynamic ecogeomorphic landforms that provide increased resilience for both natural habitats and developed communities. Despite their dynamic nature, dunes can be stabilized with vegetation and are therefore an adaptable nature-based solution that can be utilized for flood risk management. However, coastal habitats are rapidly changing and require modeling support to understand the effectiveness of vegetated dunes under changing environmental conditions. Most existing dune morphology models incorporate vegetation implicitly, using percent cover or plant height to affect sediment accretion and erosion, rather than explicitly simulating ecological processes such as mortality and dispersal. A coupled modeling approach that integrates process-based dune and vegetation models is necessary to better understand plant-sediment-water interactions and manage coastal dune systems. Through this work, we demonstrate the coupling of AeoLiS, a process-based aeolian sediment transport model with GenVeg, a generalized vegetation model under development in Landlab and parameterized with growth, functional morphology, and sand accretion of native and non-native plant species from a common garden experiment in Nehalem Bay State Park, Oregon. This work highlights how vegetation morphology affects dune building and resilience to better inform dune management and restoration actions. +
Coastal landscapes are dynamic, subject to drowning by sea level rise, erosion driven by alongshore transport, and inundation by large storm events. Coastlines are also highly developed. Along the U.S. coasts, communities continuously develop and implement beach management strategies to protect coastal infrastructure and maintain recreational value. From sediment source to sink, littoral cells often span many coastal communities. Even as physical processes grade along these littoral cells, separate communities along this coast possibly enact different management strategies. By expanding upon an existing alongshore-coupled dynamic model of coastal profile and barrier evolution, we analyze the feedbacks between alongshore and cross-shore processes as well as human response to local shoreline change across multiple communities within the same littoral cell. Incorporating the possibility of intercommunity cooperation allows us to valuate variable coastal resilience strategies for communities within a littoral cell, particularly the benefit of coordinated versus uncoordinated activities. Both sediment transport processes and a cost-benefit analysis for each community determine optimal beach management strategies. Model results provide insights useful for understanding coastal processes and planning, allowing for more robust coastal management decisions, which depend upon future rates of sea-level rise. +
Coastal urban estuaries are often impacted by water quality concerns such as bacterial contamination and harmful algal blooms that can negatively impact both human health and local industries. Historically, these impacts have been exacerbated by floods that increase the riverine discharge and alter wind patterns. Due to technical and safety constraints, however, in-situ observations during extreme events are difficult and their exact effect on water quality is typically challenging to determine. As part of a larger effort to understand how water quality changes during and following floods in estuaries around Baltimore, this study analyzed the variability in winds and river discharge. Specifically, this study utilized wind data from the NOAA station at the Frances Scott Key Bridge and river discharge data from multiple USGS river gauges from 2014-2024. Conditions during and following floods versus quiescent periods were compared. Preliminary results included the identification of 52 flooding events, defined as days when the daily discharge was higher than three standard deviations above the mean total daily discharge. During these events, the wind patterns were distinctly more northeasterly compared to low-discharge conditions, when northwesterly winds were more prevalent. Ongoing work includes investigating how variability in winds impacts circulation and residence time using a 3-D numerical hydrodynamic model. +
Coastal-plain depositional systems such as fluvial deltas are archives of past external (allogenic) forcing, such as sea-level variations, and their evolution can be described by two geomorphic boundaries: the alluvial-basement transition or upstream boundary, and the shoreline or downstream boundary. Patterns of landward/seaward migration of the shoreline (i.e., transgression/regression) and the alluvial basement transition (i.e., coastal onlap/offlap) in the rock record are often used for reconstruction of past sea-level changes. Theories for stratigraphic interpretation, however, need to be adapted to deal with internal (autogenic) processes that could play a significant role, but are to date largely unexplored. In particular, in-situ organic matter accumulation via plant growth has generally received little attention despite accounting for a significant volume fraction in most fluvio-deltaic plains and likely affect their response to sea level variations. To fill this knowledge gap, we develop a geometric model for the long-profile evolution of a fluvio-deltaic environment that accounts for sea-level cycles and organic sediment dynamics. The model assumes that sedimentological processes (i.e., inorganic and organic sedimentation) operate to preserve a linear geometry for both the delta plain or topset, and the subaqueous offshore region or forest. Changes in topset length can occur via shoreline transgression/regression, or coastal onlap/offlap, and the magnitude and timing of these changes can be directly related to the amplitude, phase and frequency of the sea-level variations. The model predicts that the maximum organic fraction occurs when the organic matter accumulation rate matches the accommodation rate, an observation consistent with field observations from coal geology. Further, we find that organic matter accumulation during the topset aggradation and organic matter erosion and decay during topset degradation generally results in substantial increase in the coastal onlap/offlap amplitude, which can result in an overestimation of the sea-level variations. These results are consistent with the discrepancy in sea-level amplitude reconstructions between sequence stratigraphic models and geochemical models over the Cretaceous.
Coasts are among the most intensely used environments on the planet, but they also present dynamic and unique hazards including flooding and erosion. Over the next century, these risk are likely to intensify across many coastal localities due to changes in environmental conditions, including sea level rise and changing wave climate patterns as induced by climate change. Managing these hazards and protecting vulnerable areas is challenging and requires an understanding of the behavior of coastal systems and longer-term prediction of their future evolution in the face of a changing climate.
Many existing one-dimensional coastal evolution models can effectively simulate the evolution of coastal environments. However, due to their 1D nature, they are unable to model the additional and combined effects of a variable water level and sea level rise. Hence, a new model, the Coastline Evolution Model 2D (CEM2D), has been built that is capable of simulating these processes.
CEM2D has been built from the 1D parent model – the Coastline Evolution Model (CEM) - that was originally developed by Ashton et al. (2001), Ashton and Murray (2006) and Valvo et al. (2006). CEM2D has been developed accordingly to the underlying assumption and mathematical framework of CEM, but applied over a two-dimensional grid. At the core of this framework is the calculation of longshore sediment transport rates using the CERC formula and Linear Wave Theory. Wave shadowing calculations are also used to ensure that sediment transport is negligible in shadowed areas. The distribution of material across the shoreface is controlled by a steepest descent formula that routes sediment from higher to lower elevations across the domain according to defined thresholds, whilst maintaining the average slope angle.
CEM2D provides a step forward in the field of coastal numerical modelling. It fills a gap between one-dimensional models of shoreline change that provide insights into the fundamental processes that control coastal morphodynamics and more complex and computationally expensive two- and three-dimensional models that are capable of simulating more complex processes and feedbacks. Key applications of CEM2D include improving our understanding of the meso-scale morphodynamic behaviour of coastal systems, their sensitivities to changing environmental conditions and the influence that climate change may have on their evolution over centennial to decadal timescales.
