Property:CSDMS meeting abstract
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Besides long-term monitoring in changes of thermal state of permafrost and active layer thickness, the knowledge of permafrost distribution at very fine scales (tens of meters) in discontinuous permafrost is still largely unknown in Qinghai-Tibet Plateau (QTP). A permafrost island was found by using geophysical investigations in the Heihe River Basin in northeastern QTP. Permafrost island was present at PT10 site beneath alpine steppe and coarse soil with a quality of gravel in surface soil (Fig. 1, Fig. 2). In contrast, permafrost is absent at SFGT site with density land cover area and relatively less gravel. The results showed that the ground surface temperature (5 cm) at PT10 site is lower in winter and higher in summer than the SFG site. The presence of permafrost is caused by soil conditions, especially by high thermal conductivity, based on field investigations. To address the controlling factors of permafrost presentences a 1D heat transfer model is used to compare the ground temperature difference between these two sites by only changing the soil conditions. +
Block-mantled hillslopes responding to river incision deliver large blocks of rock to channels. These blocks inhibit fluvial erosion by shielding the bed and reducing available bed shear stress. Block delivery by hillslopes in response to channel incision therefore feeds back on the boundary conditions felt by the hillslopes: larger numbers of blocks, or larger blocks, reduce the rate at which the hillslope boundary condition is lowering. This coupled set of feedbacks can lead to oscillatory behavior in both channels and hillslopes with periods of rapid channel incision interspersed with intervals of little to no incision. For a hillslope with a line supply of blocks (such as might originate from a resistant caprock overlying a less resistant layer), we expect that these feedbacks are strong only when the source of blocks is relatively close to the channel. Once the block source has retreated sufficiently far from the channel, blocks will weather away before reaching the channel and the oscillatory channel-hillslope feedbacks described above will cease. Our questions are 1) For how long after initial river incision through a caprock do oscillatory channel-hillslope feedbacks persist? and 2) How far must the block source retreat from the channel before such feedbacks become negligible?<br><br>We use the new BlockLab 2-D landscape evolution model to assess the spatial and temporal extent of oscillatory channel-hillslope feedbacks. We model a channel incising a lithological sequence consisting of a weak layer underlying a resistant caprock. Blocks from the caprock are delivered to the channel and inhibit river incision. We find that at early time, temporal variation in the erosion rate boundary condition felt by the hillslope is significant. As the resistant layer retreats further from the channel, variations in both the channel erosion rate and the resistant layer retreat rate decline. The rate of these reductions in variability with time is set by competition between 1) the ability of the hillslope to deliver multiple large blocks to the channel (a function of initial block size, block weathering rate, and the distance the blocks had to travel before arriving at the channel), and 2) the ability of the channel to overcome the erosion-inhibiting effects of blocks (set by fluvial discharge and the block erodibility coefficient). We find that after enough model time has passed, the resistant layer has retreated far enough from the channel that block effects on the channel are negligible and oscillatory channel-hillslope feedbacks no longer exist. This distance is primarily a function of initial block size and block weathering rate. Our results indicate that channel and hillslope evolution rates in block-mantled landscapes may be highly unsteady, depending on the strength of coupling between the channels and hillslopes.
A
Breaking waves, especially plunging breakers, generate intense turbulence and is crucial in dissipating incident wave energy, suspending and transporting sediment in the surf zone. Therefore quantifying breaking-induced turbulence kinetic energy (TKE) is essential in understanding surf zone processes. Surf zone hydrodynamic data collected at the Large-scale Sediment Transport Facility (LSTF) at the U.S. Army Engineer Research and Development center were used here. One LSTF case, with irregular waves (3 s peak period), is examined here. This case resulted in dominantly plunging type of breaker. Waves and currents were measured simultaneously at 10 cross-shore locations and throughout the water column, with a sampling rate of 20 Hz. In order to separate orbital wave motion from turbulent motion, an adaptive moving average filter is developed, involving a 5-point moving average, with additional 3-point moving average at sections with more fluctuations. This adaptive moving average filter is able to maintain more wave energy as compared with the results from 7-point moving average, while resolve more turbulence energy as compared with the result from 5-point moving average.
The TKE was calculated based on the resolved turbulence. Large TKE was generated at the water surface associated with wave breaking and dissipated rapidly downward. The TKE decreased nearly one order of magnitude downward within 15 cm. The TKE reached a minimum value at approximately 50%-80% of the water depth, and increased towards the bottom due to the generation of bed-induced turbulence. The TKE flux during wave crest and tough indicate that, at the bottom and middle layers of the water column, the TKE is transported dominantly onshore, while for the top layer, it is transported mostly offshore. +
By using a fixed-mesh approach, morphodynamic models have some difficulty to predict realistic equilibrium hydraulic geometries with vertical banks. In order to properly account for bank erosion without resorting to a complicated moving mesh algorithm, an immersed boundary approach that handles lateral bank retreat through fix computational cells is needed.<br>
One of the main goals of the FESD Delta Dynamics Collaboration is developing a tested, high-resolution quantitative numerical model to predict the coupled morphologic and ecologic evolution of deltas from engineering to geologic time scales. This model should be able to describe the creation and destruction of deltas made of numerous channels, mouth bars, and other channel-edge features, therefore requiring an approach that is able to deal with the disruption, destruction, and creation of sub-aerial land. In principle, these sub-aerial land surfaces can be randomly distributed over the computational domain. <br>
We propose a new approach in Delft3D based on the volume of fluid algorithm, widely used in the literature for tracking moving interfaces between different fluids. We employ this method for implicitly tracking moving bank interfaces. This approach easily handles complicated geometries and can easily tackle the problem of merging or splitting of dry regions characterized by vertical vegetated banks. +
By using spatially-varying estimates of seabed bottom drag (z0) the performance of ocean current and tide numerical models may be improved. To an extent, the seabed database dbSEABED is able to supply these values from data on the seabed materials and features. But then adjustments for varying dynamic (wave, flow) conditions are also required. So the data and model must work closely together. We developed methods for calculating inputs of z0 for circulation models in this way. Preliminary outputs from this new globally capable facility are demonstrated for the NW European Shelf region (NWES). +
Cellular automata models have gained widespread popularity in fluvial geomorphology as a tool for testing hypotheses about the mechanisms that may be essential for the formation of landscape patterning. For instance, studies of braided rivers using cellular automata modeling suggested that erodible banks are an essential characteristic for formation of the braid-plain morphology. In wetlands with emergent vegetation and complicated flow patterns, distilling the relevant, nonlinear interactions to a relatively simple set of rules that can be used in cellular automata modeling poses challenges, but the advantage of doing so lies in the ability to perform sensitivity analyses or examine system evolution over millennia. Here I show how a hierarchical modeling strategy was used to develop a cellular automata simulation of the evolution of a regular, parallel-drainage patterned landscape in the Everglades. The Ridge and Slough Cellular Automata Landscape model (RASCAL) suggested that this landscape structure is stable only over a small range of water-surface slopes (the driving variable for flow)—a result that both explains the limited distribution of low-gradient parallel-drainage systems worldwide and would likely have not been detected had a non-hierarchical CAM been used. Additional sensitivity analyses with RASCAL show how interactions between flow, vegetation, and sediment transport can lead to a wide variety of other regular and amorphous landscape patterns, depending on the relative strength of physical and biological feedbacks. Comparisons between RASCAL and well-known CAM models of braided stream dynamics raise interesting questions about the level of complexity that need to be incorporated into models of transitional (low- to high-energy) environments such as wet meadows and small/intermittent streams. +
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Changes in landscape structure are known to affect species macroevolution largely by altering habitat connectivity. Species can disperse across a greater area when habitats expand. Habitat fragmentation reduces gene flow and increases rates of speciation. Conversely, a shrinking habitat increases the likelihood of species extinction.
We integrated macroevolution processes (dispersal, speciation, and extinction) into the landscape evolution modeling toolkit called Landlab. Here, we present a new Landlab component, BiotaEvolver that tracks and evolves the species introduced to a model grid. In one model, surface process components evolve the landscape and BiotaEvolver evolves the species in response to topographic change or other characteristics of the model set by the user. BiotaEvolver provides a base species and users can subclass this object to define properties and behaviors of species types.
We demonstrate BiotaEvolver using scenarios of drainage rearrangement and stream species. Stream captures and high macroevolution process rates occurred within a limited combination of parameters and conditions in hundreds of model runs. The number of species increased most rapidly after a response period following a perturbation. Species numbers declined then became stable after this period. +
Changes in upstream land-use have significantly transformed downstream coastal ecosystems around the globe. Restoration of coastal ecosystems often focuses on local-scale processes, thereby overlooking landscape-scale interactions that can ultimately determine restoration outcomes. Here we use an idealized bio-morphodynamic model, based on estuaries in New Zealand, to investigate the effects of both increased sediment inputs caused by upstream deforestation following European settlement and mangrove removal on estuarine morphology. Our results show that coastal mangrove removal initiatives, guided by knowledge on local-scale bio-morphodynamic feedbacks, cannot mitigate estuarine mud-infilling and restore antecedent sandy ecosystems. Unexpectedly, removal of mangroves enhances estuary-scale sediment trapping due to altered sedimentation patterns. Only reductions in upstream sediment supply can limit estuarine muddification. Our study demonstrates that bio-morphodynamic feedbacks can have contrasting effects at local and estuary scales. Consequently, human interventions like vegetation removal can lead to counterintuitive responses in estuarine landscape behavior that impede restoration efforts, highlighting that more holistic management approaches are needed. +
Changing sea level and ice volume since the Last Glacial Maximum (LGM, 26-19 ka) has been an intensively studied topic for decades, and yet we have still not been able to adequately close the water volume budget at the LGM. At the LGM, global sea level was depressed by approximately 125-135 m relative to the present level. Past researchers have attempted to account for the storage of this water as an estimated 52*106 km3 of land-based ice. However, relative sea level, ice sheet morphology, and isostacy studies at local and regional scales have been unable to reasonably place high enough ice volumes to meet this global total, accounting for only approximately 120 m of sea-level change. This discrepancy has resulted in the so-called ‘missing ice’ problem.
We propose that some portion of this ‘missing’ water was stored not as ice, but in lakes and groundwater. Thus far, no studies have attempted to determine the volume of water stored in lakes and groundwater at the LGM. Groundwater storage could potentially account for a large volume of water, reducing the missing water volume by a significant margin. Differing topography and recharge rates may have resulted in greater terrestrial water storage, which can help us to close the water budget. Indeed, many large proglacial and pluvial lakes are known to have existed and may indicate higher groundwater levels. Furthermore, assessing groundwater levels at 500 year intervals from the LGM to the present day can provide insights into changes in water storage and inputs to the ocean over time.
It is challenging to assess groundwater levels with precision since various factors, including evapotranspiration, topography, and sea level all play a role in controlling groundwater level at a particular location. However, a recent model (Reinfelder et al., 2013) was able to estimate modern groundwater levels on a global scale. By using this model in combination with modelled topography and climate data for the LGM and each 500 year time step, we are able to compare the volume of water stored in the ground from the LGM to the present day to test whether groundwater would be a viable reservoir for LGM water storage. The model provides depths to water table, thus allowing computation of changing storage volumes.
The model covers the entire globe at a resolution of 30 arc-seconds. The large datasets and iterative nature of the model require MSI’s computational power to perform the calculations. So far, preliminary results have shown that over a metre of additional sea-level equivalent water was stored in the ground at the LGM.
Chemical erosion of regolith is of wide interest due to its role in Earth’s topographic evolution, the supply of nutrients to soils and streams, and the global carbon cycle. Theory and experiments suggest that chemical erosion rates (W) should be strongly controlled by physical erosion rates (E), which affect W by removing weathered regolith and regulating mineral supply rates to the regolith from its underlying parent material. A global compilation of field measurements reveals a wide range of relationships between W and E, with some sites exhibiting positive relationships between W and E, some exhibiting negative relationships, and others exhibiting a flat relationship within uncertainty. Here we apply a numerical model to explore the variety of W-E relationships that can be generated by transient perturbations in E in well-mixed regolith.
Our modeling results show that transient relationships between W and E during erosional perturbations can strongly deviate from steady-state relationships. These deviations ultimately result from the time lag in changes in W following imposed changes in E. As a consequence of the lag, a hysteresis develops in plots of W versus E during transients in E. This yields a positive relationship between W and E at some times during a transient perturbation, a flat relationship at other times, and a negative relationship at other times. The shape and duration of these transient hystereses can be modulated by climate and lithology, as the lag time increases linearly with a characteristic regolith production time and decreases with a characteristic mineral dissolution time, both of which are affected by climatic and lithologic factors. Our results show that even in the absence of variations in climate and lithology, however, a range of W-E relationships can be generated by a single perturbation in E. To the extent that these model results capture the behavior of chemical and physical erosion in natural landscapes, these results may aid interpretation of field measurements of W and E.
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. +
A
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. +
