Hydrodynamic Events Research Articles

A sequence of weather‐driven hydrodynamic events stimulates the formation of harmful algal blooms on an oligotrophic lake

AbstractHarmful algal blooms (HABs) are common in many eutrophic lakes and frequently associated with nutrient excesses, warm waters, and calm conditions. While HABs can also occur in oligotrophic waterbodies, bloom‐stimulating factors remain elusive for these ecosystems. Here, using a high‐frequency sensor platform supported by hydrodynamic modeling, we document a clearly linked sequence of three hydrodynamic events that immediately preceded each HAB event on Skaneateles Lake, NY during 2018. HABs were first preceded by interactions between internal waves in the thermal structure of the lake with the northern slope of the lakebed. These interactions disturbed sediments resulting in upwelling of nutrient‐rich sediment and possibly cyanobacterial cells into the lower water column. Next, moderate winds stimulated Langmuir circulation which facilitated the transport of material from the lower water column to well‐lit surface waters. Finally, the sequence culminated with a calm wind period, which is often classically associated with surface HAB formation. While individual steps in this sequence occurred independently and repeatedly throughout the year, the complete sequence occurred only eight times, immediately preceding each of the eight documented HABs. We empirically derive thresholds for and timing of the sequence to independently predict HAB occurrence and elevated cyanobacteria levels in the lake. The discovery of this specific and repeated event sequence and the identified thresholds provides the potential for forecasting of HABs days in advance. Ongoing climate change impacts, including increasing water column thermal stratification and changing wind speeds may alter the frequency, timing, and duration of this sequence and consequent HAB formation.

Oxygen evolution and its drivers in a stratified reservoir: A supply-side perspective for informing hypoxia alleviation strategies

Hypoxia in stratified waters greatly threatens aquatic ecology and societal development owing to enhanced nutrient discharge and increasing global temperature. Current research predominantly alleviates hypoxia by reducing dissolved oxygen (DO) consumption or conducting hypolimnetic oxygenation, yet their implementation has encountered bottlenecks. Therefore, this study explores the potential of increasing the inherent DO supplies in stratified reservoirs to mitigate hypoxia. High-frequency in situ observations and massive modeling experiments are integrated to discern the DO supply mode and the dominant driver of DO evolution. Results indicate that periodic thermodynamic conditions determine the DO supply relationships between oxygen sources (inflow carriage, reaeration, and photosynthesis) for different water layers. Thermal stratification causes the hypolimnion to rely mostly on the inflow for DO supply, leading to a fragile budget prone to hypoxia. However, episodic hydrodynamic events (turnover, wind stir, density current, and flood) can promote DO supply and inhibit hypoxia. Temperature and DO regimes are primarily driven by outflow conditions, followed by inflow and meteorology conditions. Furthermore, hypolimnetic hypoxia can be regulated by altering inflow volume, outflow volume, and outlet elevation. These findings highlight the importance of longitudinal solute exchange in DO evolution in stratified reservoirs, providing a basis for alleviating hypoxia through cascade reservoir operations.

CARBON STOCK, RATES OF CARBON ACCUMULATION AND DISTRIBUTION OF PARTICLES IN A LAKE OF THE ANAVILHANAS ARCHIPELAGO, NEGRO RIVER - AMAZON DURING THE LAST 1900 YEARS

Recent studies show that, despite great variability, the lake systems of the Amazon Basin have presented significant results in the accumulation and storage of organic carbon (TOC). However, the demonstration in the region is still limited and lacks more data to better estimate this non-carbon component of the region. The objective of this article was to estimate the carbon stock, the carbon accumulation rates and characterize the granulometric distribution of an Amazonian lake located in the Anavilhanas Archipelago, in the Lower Negro River region. Data were carried out using the 14C method and analyses of density, granulometry and TOC rate sof samples of a sediment core 1 meter deep. The results have shown that, during the period of 1900 cal years BP, Lake Boto presented two isolated peaks of sand particle sedimentation possibly related to major hydrodynamic events. Generally, well-defined characteristics of a lacustrine environment with sedimentation of fine silt and clay particles predominate. The sedimentation rate was 0.03 cm.year-¹ between approximately 1900 to 850 cal years BP and 0.07 cm.year-¹ in the last 850 cal years BP. It is estimated that Lake Boto has a stock of approximately 231,000 tons of TOC accumulated during the entire period. The stock of TOC is not significant as it is estimated for the soils of the Amazon. The results are an important indication of the role of the Anavilhanas Archipelago as a TOC sink.

High strain rate effects in masonry structures under waterborne debris impacts

Masonry buildings are vulnerable to extreme hydrodynamic events such as floods or tsunamis. Post-disaster surveys have shown that waterborne debris impacts can significantly damage masonry walls during these events. To simulate these actions, the current design or research practice is to compute the force–time diagram of the impact and then use it for dynamic analyses. Standing on the current knowledge, debris impacts are highly impulsive, but it is not clear if such loads are fast enough to activate the high strain rate effects in masonry, i.e. the strain rate dependency of material properties. The present study aims to answer this question, for the first time, following nonlinear Finite Element (FE) simulations. Simulations are conducted on a masonry wall, following a micro-modelling strategy, subjected to water flow and waterborne debris impact under different scenarios. It is found that the strain rates exceed the critical threshold after which strain rate effects are considerable. Such a finding, initially obtained using the minimum design demand for log-type debris imposed by ASCE/SEI 7-22, is further extended to a range of impact force–time diagrams different in impact duration and peak force (corresponding to different debris properties or flow velocity). It is also shown that the impact location (i.e. midspan or close to the boundary) affects the strain rate magnitude because of the changes in the impact stiffness and the activated failure mechanisms. Furthermore, it is found that the dynamic tensile post-elastic behaviour of the materials is the most influencing parameter in the structural response. These results open a new area in the field of assessment and design of masonry structures to waterborne debris and guide the development of future experiments, numerical simulations or design relations.

Efficient implementation of low-order-precision smoothed particle hydrodynamics

Smoothed particle hydrodynamics (SPH) method is widely accepted as a flexible numerical treatment for surface boundaries and interactions. High-resolution simulations of hydrodynamic events require high-performance computing (HPC). There is a need for an SPH code that runs efficiently on modern supercomputers involving accelerators such as NVIDIA or AMD graphics processing units. In this work, we applied half-precision, which is widely used in artificial intelligence, to the SPH method. However, improving HPC performance at such low-order precisions is a challenge. An as-is implementation with half-precision will have lower computational cost than that of float/double precision simulations, but also worsens the simulation accuracy. We propose a scaling and shifting method that maintains the simulation accuracy near the level of float/double precision. By examining the impact of half-precision on the simulation accuracy and time-to-solution, we demonstrated that the use of half-precision can improve the computational performance of SPH simulations for scientific purposes without sacrificing the accuracy. In addition, we demonstrated that the efficiency of half-precision depends on the architecture used.

An SPH-based FSI framework for phase-field modeling of brittle fracture under extreme hydrodynamic events

An SPH-based FSI framework for phase-field modeling of brittle fracture under extreme hydrodynamic events

Lunar nodal tidal cycle influences on the input of coarse sediments during the last glaciation in the deep South China Sea

Cross-slope transport of coarse sediments is thought to be dominated by gravity-flow or hyperpycnal-flow processes triggered by hydrodynamic events. However, whether long-term non-event hydrological processes can affect longitudinal transport is still unclear. Here, high-resolution (1 mm) X-ray fluorescence core scanning combined with coarse-fraction observation has been conducted on a laminated sequence (dated as last glacial 14.3–20.8 cal ka BP) of Core MD05-2892 in the South China Sea. The laminae show interbedded millimeter-scale dark and light layers. Dark layers are distinguished by coarse-grained (sand-containing clayey silt) sediments rich in Ca, Zr, and Si, whereas light layers are characterized by fine-grained (silty clay) deposits rich in K, Ti, and Fe. Accordingly, Zr/K and Si/K ratios are used to indicate lamina occurrences, and the ratios are well correlated to grayness. Spectral analyses of the ratios and grayness all present a persistent ∼18.6-yr cycle, which is interpreted as the lunar nodal tidal cycle. This signal in laminae could be related to remobilization of coarse sediments via mean high-water-line variations driven by the lunar nodal tide during the last glacial sea-level lowstand. Coarse sediments were more likely transported from the shelf break via suspended-load-dominated hyperpycnal flow to the slope to form dark layers during periods of strengthened tidal activity, while fine sediments were dispersed via hemipelagic transport to form light layers during periods of weakened tidal activity. Our study highlights for the first time that the lunar nodal tide could periodically trigger the transport of coarse sediments from the shelf to the deep sea.

Sediment resuspension and transport processes during dense water cascading events along the continental margin of the southern Adriatic Sea (Mediterranean Sea)

The near-bottom nepheloid layer in the western margin of the Southern Adriatic Sea was monitored for 8-years by measurements acquired at two mooring sites. The two moorings, equipped with CTD probes and ADCPs, are located in the Bari Canyon and in an open slope sector along the Southern Adriatic Margin. These regions are of interest because affected by episodic dense shelf water cascading events whose dynamic has direct implications on deepwater morpho-dynamic, biogeochemical cycles and trophic networks. In this work, the sedimentation flux and its interdecadal dynamic is analysed examining in detail the sedimentary processes triggered by dense water flow through the analysis of the echo records of ADCPs.The integration of hydrodynamic, turbidity and particle grain-size data provided estimates of the sediment flux, separating phases when the flow actively erodes the seabed from phases when particles are transported to the mooring location through density flows.The frequency and velocity of dense-water cascading currents vary in time and space reflecting the capacity of sediment transport. Data analysis demonstrated that the hydrodynamic event that mostly accounts for sediment transfer to the deep basin is represented by current pulses induced by the passage of dense waters. The average annual sediment flux has been quantified and the Bari canyon shows transport more than five time larger than in the open slope sector, confirming that the canyon is the dominant pathway of sediment transfer to the deep basin. In contrast, in the open slope, albeit a minor lateral sediment advection, is impacted by currents that are able to trigger intense resuspension of seabed sediments, which can contribute over 80% of the total solid load.This study allows unravelling the role of cascading in the sediment resuspension and transport processes and is essential to support deciphering the sedimentary records in the study area. The long temporal extent of the dataset used for quantification provides a reliable contribution to the Quaternary sediment budget determination.

Sedimentary architecture and glacial hydrodynamic significance of the stratified Oak Ridges Moraine, southern Ontario, Canada

High‐quality subsurface data provide new insights into the formation of Oak Ridges Moraine (ORM), an ~80 km3 sequence of stratified meltwater deposits resting >200 m above adjacent Lake Ontario. The ORM sedimentary succession comprises a three‐part regional architecture: (i) ~north–south channel sand–gravel; (ii) channel‐capping rhythmites; and (iii) east–west ridge sediments. The ORM depositional sequence overlies a regional unconformity with a cross‐cutting channel network resulting from ~north–south meltwater floods that transitioned progressively (falling stage) from a ~NNE to ENE flow direction (parallels Lake Ontario depression). Seismic profiles delineate the channels and channel fill characteristics of bank‐to‐bank channel sedimentation of thick gradational gravel–sand–mud sequences. Channel‐capping mud (~100–236 rhythmites) within multiple channels beneath the ORM landform mark a widespread interval of low‐energy, seasonally controlled subglacial pond deposition. During this quiescent period ice‐sheet thickness adjusted to flood‐induced stretching/thinning and re‐profiled slopes. New ice gradients led to east–west flow and deposition of the overlying third element, a sequence of high‐energy confined esker–fan sediments along ORM ridge. Close, sequential timing (~329 varve years) of channel, basin and ridge‐forming architectural elements supports naming this assemblage the ORM formation. Proposed ORM floods are analogous to Icelandic jökulhlaups based on the size, geometry and sedimentology. The observed rhythmite interval between flood events represents a short period (~236 years) of regional meltwater storage prior to east–west ORM flooding. The ORM channel and overlying esker‐fan sediment ridge represent two closely timed meltwater drainage events rather than formation by coalescing ice streams. The scale and timing of the ORM flood events are linked to rapid sea‐level rise, ~13.5 ka BP. This high‐resolution ORM sedimentological record may provide insights into depositional and glaciogenic controls of other large, stratified moraines. The ORM data indicate deposition in response to hydrodynamic events (outbreak floods, re‐profiled ice) rather than direct climate forcing.

Cumulants of conserved charges in hydrodynamic simulations

We introduce a fast and simple method of computing cumulants of net-proton or net-charge fluctuations in event-by-event hydrodynamic simulations of heavy-ion collisions. One evaluates the mean numbers of particles in every hydrodynamic event. Cumulants are then expressed as a function of these mean numbers. We implement the corrections due to global conservation laws. The method is tested using ideal hydrodynamic simulations of $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{{s}_{NN}}=200A$ GeV with the NeXSPheRIO code. Results are in good agreement with experimental data on net-proton and net-charge fluctuations by the STAR Collaboration.

Steller’s Sea Cow and Kelp Forest Regeneration in the North Pacific

Modern ecosystems are almost universally degraded relative to their past counterparts, from the Pleistocene to the present day. Thus, modern ecosystems may serve as poor guides to conservation actions. Conservation paleobiology is well-suited to address this challenge through enhanced understanding of systems dynamics during past periods of greater species and functional diversity, abundances, and resilience. However, past and present ecosystem dynamics must be integrated to model the future impacts of conservation actions. Here we propose a three-step, Past-Present-Future (PPF) methodology rooted in mathematical modeling. First, construct a model of primary species and interactions of the present-day ecosystem, including biotic and abiotic components. Second, integrate historical and/or paleontological data into the model to investigate past states and processes of the ecosystem, with an emphasis on critical elements (e.g., ecological engineer species) that are no longer present. Third, integrate analyses from the first two steps to predict putative future dynamics and states, and use these to make testable predictions regarding specific conservation interventions. We illustrate this approach with a study investigating impacts of the now-extinct Steller’s sea cow on north Pacific giant kelp forests. The model indicates that the historical system was distinct from the modern, with differing abundances of giant kelp and understory algae. Furthermore, the familiar kelp-dominated state is metastable, capable of rapid transitions to an urchin-dominated state if perturbed by extreme hydrodynamic events, disease-driven reductions of seastar predation, or disease coupled to extreme warming events. We explore the possibility of increasing the resilience of modern forests by artificially recreating at least some of the ecological impacts of sea cows, accounting for metabolic requirements, estimates of abundance based on recent analyses of ancient DNA, and trophic impact.

Evaporation-induced fractal patterns: A bridge between uniform pattern and coffee ring

HypothesisThe rich variety of patterns induced by evaporating drops containing particles has significant guidance for coating processes, inkjet printing, and nanosemiconductors. However, most existing works construct a uniform pattern by suppressing the coffee ring effect, and establishing the connection between them is still an academic challenge. ExperimentsWe report uniform, polygonal, and coffee ring patterns obtained by adjusting the solute concentration that sets in when an ethanol drop with dissolved ibuprofen is deposited on a silicon wafer. FindingsPattern formation involves rich hydrodynamic events: spreading, evaporative instability, dewetting, film formation, and particle deposition. Based on the distinct multiscale properties, this series of patterns is directly connected from the perspective of fractal geometry, which allows us to name them “fractal deposition patterns”. A theoretical model considering film stability is established to explain the mechanism behind pattern formation, which is well verified by experiments. This work has presented a unique strategy that can directly connect uniform, polygonal, and coffee ring patterns under the same physics, hoping to provide instructive guidance for practical applications.

Assessment of trace element contamination and effects on Paracentrotus lividus using several approaches: Pollution indices, accumulation factors and biochemical tools

Among the most common contaminants in marine ecosystems, trace elements are recognized as serious pollutants. In Corsica (NW Mediterranean Sea), near the old asbestos mine at Canari, trace elements from the leaching of mine residues have been discharged into the sea for several decades. The aim of this study was to assess the levels of contamination in this area and the potential effects on Paracentrotus lividus (Lamarck, 1816) using pollution indices, accumulation factors and biochemical tools. For this purpose, the concentration of 24 trace elements was measured in sea urchins (gonads and gut content), macroalgae, seawater column and sediment collected at 12 stations nearby the old asbestos mine and at a reference site. The bioaccumulation of trace elements occurs as follows: macroalgae > gut > gonads. TEPI contribute to highlight contamination gradients which are mainly due to the dominant marine currents allowing the migration of mining waste along the coastline. This hypothesis was supported by TESVI, which identified characteristic trace elements in the southern area of the mine. High hydrogen peroxide content, associated with elevated catalase and glutathione-S-transferase enzyme activities, were also identified at these sites and at the reference site. Trace elements contamination as well as several abiotic factors could explain these results (e.g. microbiological contamination, hydrodynamic events, etc.). The results obtained in this study suggest that oxidative stress induced by contamination does not affect the health of Paracentrotus lividus. This work has provided a useful dataset allowing better use of sea urchins and various tools for assessing trace element contamination in coastal ecosystems.

Impact of pressure drop oscillations and parallel channel instabilities on microchannel flow boiling and critical heat flux

Microchannel flow boiling heat sinks that leverage the highly efficient heat transfer mechanisms associated with phase change are a primary candidate for cooling next-generation electronics in electric vehicles. In order to design flow boiling heat sinks for such practical applications, one key obstacle is an understanding of the conditions for occurrence of dynamic two-phase flow instabilities, to which microscale flow boiling is particularly susceptible, as well as their impact on heat transfer performance. While mapping the operational regimes of these instabilities has been well-studied, with numerous stability criteria available, their impact on the heat transfer performance of heat sinks in practical applications is not understood. This work seeks to assess the impact of pressure drop oscillations and parallel channel instabilities on the surface temperature and critical heat flux in parallel microchannel heat sinks. This is achieved through measurement of time-averaged steady-state temperatures and pressures, combined with high-frequency pressure signals and high-speed flow visualization. These data are compared across three controlled flow configurations that comprise a condition of stable flow boiling, a condition where only parallel channel instabilities can occur, and a third where both pressure drop oscillations and parallel channel instabilities can occur. Experiments are performed using the dielectric refrigerant HFE-7100 in 2 cm long parallel microchannel heat sinks with square-cross-section channels (0.25, 0.5, 0.75, and 1 mm widths) at three mass fluxes (100, 400, and 1600 kg/m2s). Across this range of conditions, the time-averaged surface temperature and critical heat flux were remarkably insensitive to the occurrence of these instabilities despite the significant hydrodynamic events and transient flow patterns observed.

MESH-IN: A MESHed INlet offline coupling method for 3-D extreme hydrodynamic events in DualSPHysics

Extreme hydrodynamic events, such as those driven by tsunamis, have a significant impact on coastal environments. The Smoothed Particle Hydrodynamics computational method gained popularity in modelling these phenomena. However, high resolution is needed in areas of interest, making coupling techniques popular to reduce computational costs. Herein, a new two-step offline coupling method was developed and validated in DualSPHysics. In step 1, the simulated velocity field and water depth are measured over a two-dimensional meshed surface of a generating domain. In step 2, the interpolated flow variables are used as boundary conditions in a receiving domain with equal or higher resolution. The method was validated by using two different laboratory experiments that are representative of tsunami propagation and inundation inland. The results show a reduction of computational time of up to 17.6 times, with decreasing savings for increasing resolution in the receiving domain. The validation tests showed that the developed method allows to simulate flows in the receiving domains at nearly the same accuracy of the generating domain while also decreasing computational time. When including debris transport, improvements in accuracy occur when doubling the resolution of the receiving domain with respect to the generating domain.

Development of a small intestinal simulator to assess the intestinal mixing and transit as affected by digesta viscosity

Given the integral role of intestinal segmentation in food digestion and absorption, a Small Intestinal Simulator (SIS) was developed with segmentation contractions. The model was pneumatically driven and auto controlled. The mechanical and hydrodynamic events (i.e., maximum percentage occlusion, digesta velocity, Reynolds number) as affected by digesta viscosity under segmentation in the SIS were comparable to the available in vivo and in silico recordings. Digesta viscosity impacted luminal mixing and transit by modulating the fluid mechanical events. The mixing time of solutes under segmentation exponentially increased with the consistency index of model digesta (R2 > 0.99). A linear relationship was established between mixing uniformity and mixing time for water-like digesta, whereas exponential correlation was established for viscous systems. The study showed that the SIS is valuable in understanding the digestive and absorptive processes by closely simulating segmentation and resultant fluid mechanical conditions.

Improvement of reliability of dozers through taking into account hydrodynamic phenomena in fluid power systems

Improvement of reliability of mining machines and equipment is a complex challenge. It is required to take into account many specific operating conditions, as well as physical processes and phenomena running in such machines. Such phenomena include dynamic and hydrodynamic events. One of the factors to affect reliability of fluid power drives of mining machines is the hydrodynamic phenomena and processes in these systems. This article describes theoretically one of the hydrodynamic events, namely, a surge of pressure (overpressure) which appears in fluid power systems of mining machines in case of stop of the fluid flow while the pump keeps working and the emergency valve acts tardily, which is governed by settlement of resinous substances and power fluid decomposition products on the surface of parts of hydraulic equipment. The experimental studies into the time dependences of vibrational accelerations of the force main walls enable correlating these vibrations with pressure surges because of retar ded actuation of the emergency valve in the fluid power system of a dozer. The total level of vibrations of the force main walls in the dozers is measured by the parameter of the emergency valve series PIK during blade lifting, which agrees with the time dependences of the vibrational accelerations of the force main walls. The technical consequences of the pressure surges are described. The authors propose a diagnostic sign to judge about the behavior of emergency valves. The experimental nondestructive testing used a commercial vibration analyzer with a piezoelectric sensor.

Collapse processes and associated loading of square light-frame timber structures due to bore-type waves

Extreme hydrodynamic events such as hurricanes or tsunamis threaten coastal regions in particular. Such hazards must be assessed and appropriately incorporated into building codes to mitigate casualties and damages to coastal structures. Guidelines are often developed through experimental investigations that assume buildings remain rigid during hydrodynamic loading. To challenge this ‘rigid building paradigm’, test specimens were designed to replicate the deformation characteristics of an idealized light-frame timber structure using Froude-Cauchy similarity. Subsequently, a large-scale experimental study was conducted at the Large Wave Flume of the Coastal Research Center in Hannover. Hydrodynamic loads and load gradients were investigated to describe both the influence of an elasto-plastically modeled test specimen compared to a rigid reference model and the effect of load history on the structural loads. Finally, the collapse sequences of elasto-plastic specimens were extracted from high-speed photographs and classified into three failure mechanisms. In this study, data analyses are presented with the intention to not only inform local authorities for future development of guidelines but also serve as calibration and validation data for improving numerical methods. • A new methodology to replicate light-frame wood structures is provided. • Realistic tsunami on land conditions are resembled in large-scale experiments. • Structural loads due to bore-like flows differ for rigid and non-rigid structures. • Collapse processes are disseminated and categorized in three failure mechanisms. • Failure mechanisms of idealized light-frame wood structures vary significantly.

A non-overlapping high accuracy parallel subdomain closure for compact scheme: Onset of Rayleigh-Taylor instability by ultrasonic waves

Rayleigh-Taylor instability (RTI) occurs at the interface of two media when the heavier fluid is accelerated into the lighter fluid and is a prototypical hydrodynamic event present in many physical events. In high energy physics, this manifests itself across a wide range of length scales from nuclear confinement fusion at micron-scale to supernova explosion at terra scales. RTI can also be viewed as a baroclinic instability prevalent in engineering, geophysics, and astrophysics, a pedagogic description of which is given in Sengupta et al. (2021) [12] with respect to the experimental results of Read (1984) [22]. Here, a recently proposed non-overlapping parallel algorithm is used to solve this three-dimensional canonical problem, having the unique property of not distinguishing between sequential and parallel computing, using 4.19 billion points and a refined time step of 7.69×10−8s. The problem achieves the required density gradient by considering two volumes of air at different temperatures (with a temperature difference of 200 K) separated by a non-conducting, impermeable partition at the onset of the experiment, which is removed impulsively at t=0. The resulting buoyancy force at the interface acting from top to bottom is the seed of the baroclinic instability. Present high precision computation enables one to capture the ensuing RTI triggered by ultrasonic waves created at the interface.

Dam-Break Waves’ Hydrodynamics on Composite Bathymetry

Among others, dam-break waves are a common representation for tsunami waves near- or on-shore as well as for large storm waves riding on top of storm surge water levels at coasts. These extreme hydrodynamic events are a frequent cause of destruction and losses along coastlines worldwide. Within this study, dam-break waves are propagated over a composite bathymetry, consisting of a linear slope and an adjacent horizontal plane. The wave propagation on the slope as well as its subsequent inundation of the horizontal hinterland is investigated, by varying an extensive set of parameters, for the first time. To that end, a numerical multi-phase computational fluid dynamics model is calibrated against large-scale physical flume tests. The model is used to systematically alter the parameters governing the hydrodynamics and to link them with the physical processes observed. The parameters governing the flow are the slope length, the height of the horizontal plane with respect to the ocean bottom elevation, and the initial impoundment depth of the dam-break. It is found that the overland flow features are governed by the non-dimensional height of the horizontal plane. Empirical equations are presented to predict the features of the overland flow, such as flow depth and velocities along the horizontal plane, as a function of the aforementioned parameters. In addition, analytical considerations concerning these dam-break flow features are presented, highlighting the changing hydrodynamics over space and time and rising attention to this phenomenon to be considered in future experimental tests.