We present the analysis of continuous remotely sensed data (hourly collections of high-resolution daytime videos) of the Nilahue Intermittently Open/Closed Estuary (IOCE) on the central Chilean Pacific seaboard (34.48°S, 72.00°W). Videos are automatically processed on-the-fly using state-of-the-art Artificial Intelligence algorithms to produce time series of river mouth metrics, which, in combination with measured and modeled hydrological (rainfall, river discharge, lagoon water level), oceanographic (tides and waves), and environmental (salinity) variables, provide unprecedented insights for understanding, diagnosing, and forecasting multi-scale processes in these fragile and rapidly evolving ecosystems. The initial analyses cover a time frame from April 2023 to November 2024, spanning two complete winter seasons and one summer. In particular, during 2023, significant rainfall associated with the El Niño/Southern Oscillation (ENSO) led to extreme flooding and a complete river mouth opening and reset, allowing us to track the subsequent morphodynamical processes and gradual closure of the mouth. In this talk, we also report on periods of artificial openings during spring-summer-autumn (December to April), summarizing the different conditions and outcomes. Based on the captured data and analysis, we discuss the possibilities of building physics-based and data-driven forecasting capabilities to understand lagoon functioning and, from there, provide guidance for IOCE management to ensure their ecological integrity amidst uncertain environmental changes.

Floods are among the most destructive natural hazards, making it essential to assess how climate change may influence their frequency and intensity. Yet, future flood behavior remains uncertain and varies regionally. This study uses continuous hydrological simulation with a calibrated and validated Hydrologic Engineering Center's Hydrologic Modeling System model to analyze historical and future peak flows in the urbanized Marga Marga Creek basin in coastal Chile. Historical daily meteorological data were stochastically disaggregated to hourly resolution to model multiple discharge series and account for internal climate variability. Future simulations were based on projections from eight downscaled and bias-corrected general circulation models under the SSP5-8.5 scenario. Results show that most historical peak flows were below 50 m(3)/s, driven by daily rainfall under 17 mm. Toward the end of the century, peak discharges are projected to decline relative to the 1980-2014 baseline. A nonstationary frequency analysis was conducted, but high inter-model variability limits its reliability for this basin. Overall, continuous simulation captures interactions among climate, hydrology, and land use, offering a valuable approach to address uncertainty. The findings support the design of early warning systems based on meteorological forecasting and the integration of flood risk into urban planning and multihazard strategies, especially in regions with limited observational data.

Remote sensing analysis along a section of the coast of central Chile was used to quantify coastal evolution. The results at a single beach were contrasted with simple linear superposition models to identify parameters that could correlate to the observed change, including tectonic-induced vertical change, climatic indices, wave parameters, and riverine discharges. It was found that riverine discharges were significant contributors to this linear model. Next, the coastal evolution analysis was conducted over a large section of the coast, encompassing several watersheds. The shoreline change showed a mesoscale pattern of propagating erosion, that was interspersed by river discharges, although the trends were similar across cells. It is speculated that these observations point to mesoscale and watershed processes to be relevant and ought to be considered in assessing and forecasting coastal evolution.

This study investigates infragravity wave propagation in the Nilahue River estuary, a small Intermittently Open/Closed Estuary (IOCE) on Chile’s Pacific coast (34.48º S; 72.00ºW). The estuary, critical for ancient sea-salt production, experiences artificial breaching due to reduced river discharges and energetic swells that enhance sediment accumulation at the river mouth. Field measurements conducted in August 2023, during low river discharge, spring tides, and high swells, revealed that infragravity waves propagate at least 3 km upstream the estuary during flood tides. Data from acoustic Doppler velocimeters confirmed infragravity wave-driven scatterer fluctuations potentially affecting sediment transport dynamics. A second experiment conducted in July 2024 expands on these findings by incorporating turbulence, echosounder, salinity and turbidity measurements to improve our understanding of IG waves’ role in sediment transport and mixing in IOCEs.

Small estuaries characterized by seasonally varying freshwater discharge are frequently found along microtidal coasts dominated by energetic wave conditions. These estuaries often feature a sediment bar that follows a natural seasonal cycle, alternately connecting and disconnecting the estuary from the ocean. Such systems are known as Intermittently Open and Closed Estuaries (IOCEs). During prolonged dry seasons with low river discharge, some IOCEs may not open naturally leading to water stagnation, degraded water quality, and increased flood risk within the estuary. Artificial breaching of the sediment bar is a common intervention aimed at restoring the connection to the ocean. However, currently there is no standardized protocol to guide when, where, or how such breaches should be conducted effectively, since the closure mechanisms are highly site-dependent. In this study, a hydraulic model was implemented for an IOCE located in Laguna Cahuil, Chile, to evaluate the effects of artificial opening scenarios on the propagation of tides upstream the estuary. A series of scenarios were simulated, combining openings of varying geometries and locations with different river discharges and tide conditions. The results show that the hydrodynamic response of the estuary is strongly dependent on the geometry and length of the opening, and that tidal propagation upstream is closely related to the magnitude of river discharge and the duration of floods.

Tsunami-induced resonance has been a topic of significant interest. However, usually the focus is set in understanding the response from either specific or a few events, which may prevent generalization of whether strong bathymetric control occurs. Here, 19 locations and 16 tsunamis were analyzed using standard methods. A set of statistical parameters was introduced to aid in the assessment, leading to the categorization of bays in terms of their resonant capacities. Next, the morphology of these locations was analyzed to identify the type of features driving this response. Adding to other well-known features, it was found that the steepness of the headlands defining a bay in planform is relevant in isolating it from surrounding coasts, thereby enhancing its filtering capacity.

Intermittently closed estuaries provide important ecosystem services but are often overlooked in coastal and catchment research and management. These estuaries are highly vulnerable to human and climate disturbances due to their episodic closure to the ocean, yet remain understudied. This study maps 2245 intermittent estuaries globally, whose catchments currently support 55 million people, with projections of up to 101 million by 2100. Analysis of three decades of scholarly literature revealed that only 7% of these estuaries have been studied. Research on intermittent estuaries comprises 0.5% of all estuarine literature, despite representing 4-5% of estuaries globally. Major research gaps exist in Asia, South America, and Africa-regions with large, vulnerable populations. Over 90% of research on intermittent estuaries is conducted in (southern) Africa, Oceania, and North America, with most studies focusing on local physico-chemical and eco-hydro-geomorphological processes. This assessment underscores the need to expand research priorities to include ecosystem services, climate and human disturbances, and management, with greater international collaboration and leadership from intergovernmental organisations.

A simplified model using 1D topobathymetric profiles for generating tsunami inundation maps is implemented and evaluated. The approach is a modification of the ASCE Energy Grade Line Analysis, that allows estimation of the maximum inundation distances using an iterative method. The modified methodology is implemented in three coastal cities in central Chile and compared with a database of 5400 full tsunami simulations obtained from a Nonlinear Shallow Water Equations solver. The key parameter of the model is based on the Froude number, for which three parameterizations and a range of values are tested. Results show that errors in the estimation of the areal extent of the inundation can be as low as 4%, after calibration. However, calibration is site specific and the optimal solution depends on the geographical characteristics of the area of interest. A sensitivity analysis based on the aleatoric sampling of the full tsunami simulation database show that as little as 100 inundation maps are required to perform the calibration of the model. This is a manageable number that offers reduced computational costs when compared with full tsunami simulations, and even those required to train other surrogate models using machine learning.

Rogue waves have been the subject of intensive research and scientific debates over the last 20 years. In oceanographic contexts, they are defined as infrequent large waves (with heights more than 2 times the significant wave height of the carrier field) suddenly appearing among a group of smaller wind generated waves (Haver and Anderson, 2000). They have been seldom observed in nature, yet causing significant damage and casualties (Kharif and Pelinovsky, 2003). In the present contribution, we present field measurements of infragravity waves penetrating into a shallow bar-built estuary located in the Pacific border of Central Chile (34.48°S, 72.00°W). We show that the shallow and narrow canal connecting the river to the sea acts as a natural low-pass filter for swell frequencies, as it has been previously documented (Willliams et al., 2016; McSweeney et al., 2020). The quasi-periodic entrance of infragravity motions into the estuary evolve over a shallow bathymetry as highly nonlinear long-waves that fission into solitonic wave trains. The statistical analysis of the measured wave heights show that the resulting field is of strongly non- Gaussian nature, with a frequent appearance of rogue waves.

In this work, we studied the spatial variability of wave erosion (ET) caused by periodic waves through the development of a simple numerical model on a large-scale (headland - bay scale) over a short-term (annual scale). This model used a wave ray tracking approach and parametrization for wave breaking based on slope and incident wave conditions to investigate the influence of nearshore geometric characteristics: bathymetric planform and cross-shore geometry, on the wave energy transfer from offshore to the shoreline. The model estimated (1) the location of the breaking point and the establishment of the surf zone, (2) the erosive force of those waves reaching the shoreline, and(3) the alongshore and intertidal variations of wave-driven coastal erosion. Synthetic bathymetries simulating straight and sinuous planform rock coasts, the latter with and without alongshore slope variability, were used in the initial tests. In addition, measured bathymetries of two natural rock coast examples were used to examine the model representation of the general wave erosion behavior. Model results showed that the spatial variability of wave energy transfer and the consequent erosion are strongly influenced by the geometry of nearshore bathymetry and deep-water wave regime (height and period). Findings indicated that some segments of a sinuous shoreline may be eroded at higher (headland apex and flanks) and lower (bay center) rates. A conceptual model that describes the spatial variability of wave erosion as a result of the relative influence of geometric characteristics and oceanic settings was developed in this work. Despite its simplified assumptions, the model showed how the nearshore bathymetric geometry influences wave dissipation and the subsequent alongshore distribution of wave erosive force.

We document a field experiment in which a path to strongly interacting soliton gas dynamics is observed within an intermittently open/closed estuary. We show that the shallow estuary mouth acts as a low-pass filter for incoming ocean waves, damping energy within the swell frequency band (0.04–1 Hz) and allowing surf-zone generated infragravity waves (frequency band 0.004–0.04 Hz) to enter the semienclosed shallow lagoon formed near the estuary mouth. These long waves penetrate under highly nonlinear conditions with Ursell numbers consistent with multisoliton fission regimes. The k–ω spectrum of the incident wave trains is consistent with solitonic kinematics, demonstrating that solitons are released by the fission of incoming infragravity waves at the lagoon entrance. Continuous injection of solitonic wave trains and intense wave-wave interactions enhanced by the shallow and gradually varying bathymetry within the estuary lagoon lead to a quasistationary soliton gas regime with a substantially increased probability of rogue wave occurrence compared with linear wave theory. The Korteweg-de Vries nonlinear Fourier transform reveals that nearly half of the measured signal energy is explained by solitonic modes, confirming the key role that solitons have in enhancing rogue wave emergence in natural coastal settings.

Extreme Sea Levels (ESL) are episodes of infrequent combinations of high tides, storm surges, and waves, also enhanced by the rising of the mean sea level due to Climate Change. These events have the potential to cause devastating flooding, erosion, and inundation, resulting in widespread damage to infrastructure and ecosystems (Oppenheimer et al., 2019). Usually, the future projections of ESL rely only on offshore wave data due to the high computational costs of downscaling multiple Global Climate Models (GCMs) and resolving the required directional and spectral characteristics as waves shoal and refract while approaching the coast. Furthermore, the lack of data for local foreshore slopes restrains the accurate estimation of wave runups (Serafin et al., 2019). In this study we address these limitations by considering nearshore spectral wave models to compute wave climates in shallow waters and using estimations for the local foreshore slope to compute ESL.

Tsunamis are rare events that can cause widespread damage and devastation even at remote locations far removed from the source location. Among the reasons for this damage potential are their minimal energy loss during their propagation, as well as being prone to energy trapping by mesoscale features such as continental shelves and shallow water bays, which may promote standing and edge wave activity. This may lead to an enhanced tsunami response in certain locations, which can exacerbate the hazard compared to surrounding locations. This has prompted us to attempt to understand to which extent, resonance can drive subcritical tsunami flows. To this end, we carried out high-resolution modeling of tsunami inundation at three different locations along the coast of Chile. The aforementioned Coquimbo, the large metropolitan area of Valparaíso and Viña del Mar, and the main port of San Antonio.

The occurrence of mega-tsunamis over the last couple of decades has greatly increased the efforts of the research community and practitioners to work hand in hand to reduce risks from these highly destructive threats. Protecting the population through evacuation is the best alternative for avoiding loss of life in the wake of the occurrence of a tsunamigenic earthquake. Therefore, guaranteeing the proper state of evacuation routes is very important to ensuring appropriate movement to the safe zones. This study carries out a detailed analysis of possible evacuation scenarios, considering the actual state of the escape routes of Iquique, a Chilean city prone to tsunamis, with a substantial number of urban micro-scale vulnerabilities, i.e., elements that obstruct or complicate pedestrian flow. The quantification of the delay in evacuation processes resulting from the presence of urban micro-vulnerabilities is carried out through micro-scale agent-based model (ABM) simulations. In addition, these results are integrated with high-resolution tsunami inundation simulations, allowing for an estimation of the potential number of people that the tsunami may reach under different scenarios by emulating the dynamics and behavior of the population and the decision-making regarding the starting time of the evacuation.

Intermittently open/closed estuaries provide important ecosystem services but are often overlooked in coastal–catchment research and management. These estuaries are highly vulnerable to human/climate disturbances due to their tendency to close off from the ocean, yet their processes/dynamics remain under-researched. This study maps the global distribution of at least 2,245 intermittent estuaries, whose catchments currently support 55 million people, with projections rising to 101 million by 2100. Assessing three decades of scholarly articles indicated that only 7% of these sites have been studied. Academic literature on intermittent estuaries accounted for 0.5% of the total literature on all estuaries, despite these systems representing 4–5% of the estimated total number of global estuaries. Significant research gaps exist in Asia, South America, and Africa, where the largest, most susceptible populations reside. 90% of the existing research on intermittent estuaries is conducted in (southern) Africa (42%), Oceania (35%), and North America (14%), predominantly through domestic efforts. From 1992 to 2023, 60% of the research focused on physio-chemical and eco-hydro-geomorphological topics, with minimal attention to ecosystem services, climatic/human disturbances, and management. Our assessment underscores the need for increased focus on intermittent estuaries and suggests strategies to promote international collaborations, including leadership from intergovernmental organisations.

The quantity and accuracy of satellite-geodetic measurements have increased over time, revolutionizing the monitoring of tectonic processes. Global Navigation Satellite System (GNSS) and satellite radar signals provide observations beyond ground deformation, including how earthquake and tsunami processes affect variations in the ionosphere. Here, we study the Hunga Tonga Hunga Ha’apai (HTHH) volcanic eruption 2022 and its associated tsunami propagation with the analysis GNSS derived Total Electron Content (TEC), Synthetic Aperture Radar (SAR) Sentinel-1 data, complemented with tide gauge observations. We utilize GNSS sites data within a ~ 5000 km radius from the volcanic eruption for estimating the ionospheric perturbation as Vertical TEC. We give evidence on the detection of acoustic gravity, internal gravity, and atmospheric Lamb waves signatures in the TEC perturbation. In particular, the internal gravity waves that concentrated in the southwest of Tonga, directly correlates with the observed tsunami propagation direction as accounted by the tide gauge measurements. However, the acoustic gravity wave signature in the TEC is dominant in the north direction suggesting a surface deformation, which could be verified using Sentinel-1A SAR amplitude data. The analysis presented herein shows that within 5 h of the volcanic eruption, the central part of the HTHH island landscape disappeared with the biggest explosion. The unprecedented detail resolved by integrating satellite data yields previously unknown details of the deformation of the 2022 HTHH volcano eruption.

Rip-currents, commonly observed on natural beaches, are vorticity induced and part of large scale near-shore circulations. The questions arise: how do bathymetric gradients magnitudes relate to rip velocities? how does rip current vorticity scale with wave characteristics and dissipation? What is the dynamics of the large scale 2D vorticity? To address these questions, we utilize a Non Linear Shallow Water model with a shock-capturing scheme. It is validated with preexisting experiments of wave induced rip-currents on uneven bathymetries generated by irregular waves. To do so the enstrophy (spatially averaged square of the vorticity) is shown to be a relevant metric to calibrate the bottom friction coefficient of the model. The numerical study based on a large number of simulations with monochromatic wave forcing shows that the more non-uniform the bathymetry is, the stronger the gradients in wave dissipation are and the stronger the enstrophy is. The rip current velocity is shown to linearly increase with the square root of the local enstrophy. The wave-averaged shallow water vorticity equation terms are evaluated. It is suggested that large scale 2D vorticity dynamics mainly result from an equilibrium between vorticity production, vorticity advection by the circulation and dissipation by bottom friction.

A wide variety of hydraulic and coastal flows can be modeled using shallow water theories, where the so-called Serre-Green-Naghdi (SGN) equations constitute a fully nonlinear and weakly dispersive wave theory that has been successfully applied in fluvial and maritime contexts. In the present contribution, we show that SGN models with wave-breaking parameterizations can reproduce challenging nonlinear processes in the surf and swash zones including wave-wave interactions and infragravity wave generation from a narrow-band swell spectrum. The excellent performance of the model motivates us to explore its application to a simplified shallow bar-built river configuration where surf zone-generated infragravity waves may propagate upstream the river. We show that long-wave penetration is controlled by the Froude number over the bar, and that these nonlinear long waves may give rise to a solitonic dynamics. The power spectral density (PSD) signature of free surface time series with a slope of similar to f(-1) in the infragravity range is consistent with the latter, as also found in field observations. Transferring of energy into lower frequencies is observed in the numerical experiment as long waves propagate upstream; nevertheless, low-frequency energy also cascades back into the swell energy band. Standard linear Fourier analysis may fail in showing the hidden solitonic dynamics, so nonlinear techniques would need to be applied to fully elucidate the fate of the long-wave energy while propagating upstream of river mouths.

This research presents a methodology to study the behavior of buildings subjected to seismic and tsunami loading in sequence, considering soil structure interaction effects through a complete dynamic analysis. The case-study building is an RC frame, which is assumed to be located in a coastal city in Chile, and built on sandy soil. A 3D Soil-Structure Interaction (SSI) model, including the non-linear behavior of both the structure and the soil using finite element method (FEM) was presented. Synthetic seismic ground motion records and tsunami inundation time histories were generated, consistent with the same earthquake source. Building performance was first assessed considering the SSI model for each hazard separately and compared to a Fixed Base (FB) model. Then, the SSI model was subjected to seismic and tsunami loading in sequence. Engineering Demand Parameters (EDPs) of roof displacement, interstory drift ratio (IDR) and reinforcement strain in beams and columns were analyzed. These EDPs presented a larger response to the tsunami when the response to the previous earthquake was larger. Finally, two vertical evacuation building scenarios were studied: the location of the refugees and the effect of an aftershock occurring simultaneously with the tsunami inundation. Results showed that the location of the refugees did not generate significant differences in the building response, and the aftershock increased the response only when it coincided with the maximum tsunami force.