Tsunami Penetration in Tidal Rivers, with Observations of the Chile 2015 Tsunami in Rivers in Japan

Tolkova, Elena

doi:10.1007/s00024-015-1229-0

Cited by 8 publications

(4 citation statements)

References 20 publications

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“…For example, the MWL and the extreme high water level become much higher at proxigean spring tide compared with the situation without low‐frequency tides, for example, up to 0.5 m higher in the upper Changjiang Estuary. Similarly, low‐frequency surges and tsunami waves also can propagate more inland in river estuaries (Tolkova, 2017). Thus, long inland propagation of the low‐frequency long waves needs to be considered in assessment of extreme high water level and management of compound floods in river estuaries with significant river‐tide interaction.…”

Section: Discussionmentioning

confidence: 99%

Strong Inland Propagation of Low‐Frequency Long Waves in River Estuaries

Guo

Zhu

et al. 2020

Geophysical Research Letters

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Tidal waves traveling into estuaries are modified by channel geometry and river flow. The damping effect of river flow on incident astronomical tides is well documented, whereas its impact on low-frequency tides like MSf and Mm is poorly understood. In this contribution, we employ a numerical model to explore low-frequency tidal behavior under varying river flow. MSf and Mm are locally generated by frictional mechanisms inside an estuary, and they are larger in amplitude far upstream in tidal rivers and persist landward of the point of tidal extinction. Increasing river flow nonlinearly modulates the longitudinal variations of MSf and Mm amplitudes. This is dynamically explained by flow-enhanced asymmetry in subtidal friction over the spring-neap (MSf) and perigee-apogee (Mm) cycles, respectively. Estuaries act as frequency filters, where low-frequency waves decay at a smaller rate and propagate more inland than high-frequency waves. Strong inland penetration of low-frequency tides informs compound flood management.

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Section: Discussionmentioning

confidence: 99%

Strong Inland Propagation of Low‐Frequency Long Waves in River Estuaries

Guo

Zhu

et al. 2020

Geophysical Research Letters

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“…Several studies have been carried out to understand whether tide-tsunami interactions enhance/reduce tsunami elevation, flow speed, and arrival times. Based on observations and/or numerical experiments, various authors have found that tsunami inundation in rivers, inlets, harbors, and estuaries is strongly affected by tidal conditions (e.g., Kowalik et al, 2006;Kowalik and Proshutinsky, 2010;Zhang et al, 2011;Lee et al, 2015;Ayca and Lynett, 2016;Shelby et al, 2016;Tolkova, 2016;Ayca et al, 2017). Causes of tidetsunami interaction are attributed to tidally induced currents and changes in the depth altering the background conditions during the propagation of the tsunami from its source (Weisz and Winter, 2005), both effects are small in the open ocean but increase as the tsunami shoals, mainly in coastal and bathymetric particular configurations as energetic tidal channels communicating large bodies of water or coastal configuration that can induce resonance effects between large scale shallow shelfs, narrow channels, islands, etc.…”

Section: Methods and Limitationsmentioning

confidence: 99%

Probabilistic Tsunami Hazard Assessment in Meso and Macro Tidal Areas. Application to the Cádiz Bay, Spain

et al. 2021

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Tsunami hazard can be analyzed from both deterministic and probabilistic points of view. The deterministic approach is based on a “credible” worst case tsunami, which is often selected from historical events in the region of study. Within the probabilistic approach (PTHA, Probabilistic Tsunami Hazard Analysis), statistical analysis can be carried out in particular regions where historical records of tsunami heights and runup are available. In areas where these historical records are scarce, synthetic series of events are usually generated using Monte Carlo approaches. Commonly, the sea level variation and the currents forced by the tidal motion are either disregarded or considered and treated as aleatory uncertainties in the numerical models. However, in zones with a macro and meso tidal regime, the effect of the tides on the probability distribution of tsunami hazard can be highly important. In this work, we present a PTHA methodology based on the generation of synthetic seismic catalogs and the incorporation of the sea level variation into a Monte Carlo simulation. We applied this methodology to the Bay of Cádiz area in Spain, a zone that was greatly damaged by the 1755 earthquake and tsunami. We build a database of tsunami numerical simulations for different variables: faults, earthquake magnitudes, epicenter locations and sea levels. From this database we generate a set of scenarios from the synthetic seismic catalogs and tidal conditions based on the probabilistic distribution of the involved variables. These scenarios cover the entire range of possible tsunami events in the synthetic catalog (earthquakes and sea levels). Each tsunami scenario is propagated using the tsunami numerical model C3, from the source region to the target coast (Cádiz Bay). Finally, we map the maximum values for a given probability of the selected variables (tsunami intensity measures) producing a set of thematic hazard maps. 1000 different time series of combined tsunamigenic earthquakes and tidal levels were synthetically generated using the Monte Carlo technique. Each time series had a 10000-year duration. The tsunami characteristics were statistically analyzed to derive different thematic maps for the return periods of 500, 1000, 5000, and 10000 years, including the maximum wave elevation, the maximum current speed, the maximum Froude number, and the maximum total forces.

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“…Linear-friction is attractive, if it works well enough in practice, because the model retains all the practical benefits of linearity for simulating global propagation (e.g., unit-source solutions are exact). The use of a constant f is not essential to preserve linearity; often linear friction is implemented by linearizing a quadratic drag model about a reference depth and velocity (e.g., Tolkova, 2015). However the use of a FIGURE 5 | Comparison of nearshore gauge results in two models which use different solvers on the global grid; one solves the full NSWE, the other solves the LSWE with a nonlinear Manning-friction term.…”

Section: Linear Shallow Water Equations With Constant Linear-frictionmentioning

confidence: 99%

Global Dissipation Models for Simulating Tsunamis at Far-Field Coasts up to 60 hours Post-Earthquake: Multi-Site Tests in Australia

Davies¹,

Romano²,

Lorito³

2020

Front. Earth Sci.

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At far-field coasts the largest tsunami waves may occur many hours post-arrival, and hazardous waves may persist for more than 1 day. Such tsunamis are often simulated by nesting high-resolution nonlinear shallow water models (covering sites of interest) within low-resolution reduced-physics global-scale models (to efficiently simulate propagation). These global models often ignore friction and are mathematically energy conservative, so in theory the modeled tsunami will persist indefinitely. In contrast, real tsunamis exhibit slow dissipation at the global-scale with an energy e-folding time of approximately 1 day. How strongly do these global-scale approximations affect nearshore tsunamis simulated at farfield coasts? To investigate this we compare modeled and observed tsunamis at sixteen nearshore tide-gauges in Australia, generated by the following earthquakes:

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Tsunami Penetration in Tidal Rivers, with Observations of the Chile 2015 Tsunami in Rivers in Japan

Cited by 8 publications

References 20 publications

Strong Inland Propagation of Low‐Frequency Long Waves in River Estuaries

Strong Inland Propagation of Low‐Frequency Long Waves in River Estuaries

Probabilistic Tsunami Hazard Assessment in Meso and Macro Tidal Areas. Application to the Cádiz Bay, Spain

Global Dissipation Models for Simulating Tsunamis at Far-Field Coasts up to 60 hours Post-Earthquake: Multi-Site Tests in Australia

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