HyFlux2: a Numerical Model for the Impact Assessment of Severe Inundation Scenario to Chemical Facilities and Downstream Environment

Following a number of catastrophic dam-failure accidents and the accompanying environmental disasters (e.g. Baia Mare, Romania 2000), the tailings ponds of mining activities entered in the scope of the Seveso Directive. This Directive, which deals with the control of major accident hazards, requires the assessment of consequences for all relevant accident scenarios, including those referring to dam rupture. The HyFlux2 model has been developed to simulate flood inundation due to dam break. However, it is able to simulate other severe inundation scenarios such as tsunami-wave run-up and flash flood. The model solves the conservative form of the two-dimensional shallow water equations using the finite volume method. The interface flux is computed by a Flux Vector Splitting method based on a Godunov-type approach. A second-order scheme is applied to the water surface level and velocity, assuring the balance between fluxes and sources also for complex bathymetry and topography, i.e. also in presence of bottom steps and shorelines. The second-order scheme provides results with high accuracy, also in the presence of dry/wet fronts. The model adopts the raster grid so that a GIS Digital Elevation Model can be directly imported into the model. The developed model is validated in this paper with a dam-break case study. It is shown that the HyFlux2 model can correctly account for complex real dam-break flows, giving a satisfactory prediction of the major characteristics such as water depth, water velocity, flood extent, and flood-wave arrival time. It is also demonstrated that the model is robust, computationally efficient and fully mass conservative. The results provided by the model are of great importance for the assessment and management of risk in a number of Seveso establishments with certain characteristics. In case of tailings ponds this information is necessary for modelling the dispersion of pollutants to the downstream environment. Similarly, in the case of downstream chemical facilities where a dam-break can provoke chemical releases, the model provides the necessary information to assess the impact and the risk of such a scenario.JRC.G.7-Traceability and vulnerability assessmen

01 April 2007 Solomon Island Tsumani: Case Study to Validate JRC Tsunami Codes

On April 1st 2007 a large earthquake of magnitude 8.1 occurred offshore Solomon Islands at 20:40:38 UTC. Numerical simulations of the tsunami event caused by the earthquake have been performed to compare the results obtained by the SWAN-JRC code (Annunziato, 2007), the TUNAMI (Imamura, 1996) and the HYFLUX2 (Franchello, 2008). The analysis conducted using these numerical simulations were also compared with NOAA-MOST code unit source results. The tsunami event has been simulated considering several options for the seismological parameters as input data: Finite Fault Model (USGS, 2007), the Centroid Moment Tensor fault model and other mechanisms derived from the field survey analysis (Tanioka model). The main aim of this study is to assess how the different fault models affect the overall results and to perform a comparison among the various codes in the wave propagation phase. Another objective of this study is to use HYFLUX2 code to calculate inundation and compare the simulation results with site field measurements. The study has been separated into two main parts. The first one represents the collection of information about focal mechanisms: the fault analysis in chapter 4 covers one of the main aims of this research where different fault scenarios have been tested using published field data. The second part describes the different calculations that have been performed in order to analyze the response of the wave propagation models to various fault deformation models. For the inundation assessment, more detailed calculations at 300m grid size resolutions have been performed, using the fault model that best represent the deformation. The calculations in the propagation assessment subsection were performed using: SWAN-JRC, HYFLUX2, TUNAMI-N2 and NOAA-MOST code. In the inundation assessment the HYFLUX2 numerical code, initialized with the Tanioka fault model was used. The deformation comparison with field measured data shows that none of the ¿quick¿ fault mechanism was able to estimate correctly the measured value. The best model is the empirical model by Tanioka which was obtained by trying to reproduce the measured value. From the published fault mechanism the one that shows a better correlation with measurements is the simple cosinuosoidal model. Results of simulations done with 300 m grid, show a maximum wave height of 7.5 m. Though the maximum run up reported was 10 m in Tapurai site, Simbi Island, the simulation results are encouraging.JRC.DG.G.2-Global security and crisis managemen

Validation of the JRC Tsunami Propagation and Inundation Codes

In the last years several numerical codes have been developed to analyse tsunami waves. Most of these codes use a finite difference numerical approach giving good results for tsunami wave propagation, but with limitations in modelling inundation processes. The HyFlux2 model has been developed to simulate inundation scenario due to dam break, flash flood and tsunami-wave run-up. The model solves the conservative form of the two-dimensional shallow water equations using a finite volume method. The implementation of a shoreline-tracking method provides reliable results. HyFlux2 robustness has been tested using several tsunami events. The main aim of this study is code validation by means of comparing different code results with available measurements. Another objective of the study is to evaluate how the different fault models could generate different results that should be considered for coastal planning. Several simulations have been performed to compare HyFlux2 code with SWAN-JRC code and the TUNAMI-N2. HyFlux2 has been validated taking advantage of the extensive seismic, geodetic measurements and post-tsunami field surveys performed after the Nias March 28th tsunami. Although more detailed shallow bathymetry is needed to assess the inundation, diverse results in the wave heights have been revealed when comparing the different fault mechanism. Many challenges still exist for tsunami researchers especially when concern to early warning systems as shown in this Nias March 28th tsunami.JRC.G.2-Global security and crisis managemen

RESPONSE OF THE GDACS SYSTEM TO THE TOHOKU EARTHQUAKE AND TSUNAMI OF 11 MARCH 2011

The Tohoku Tsunami of 11 March 2011 was successfully identified and classified as Red alert by the GDACS system only when reliable and more correct estimations of the originating event have been provided to the system by the international seismological networks. Nevertheless the early analysis of the event by the comparison of the scenario calculations with the sea level could give important information on the real extent and impact of the Tsunami. The paper describe the response of the GDACS system and identify the lessons learned that determined changes in the logic and the procedures of the Tsunami calculations strategy.JRC.G.2-Global security and crisis managemen

Assessment of Tsunami Risk to an Oil Refinery in Southern Italy

Industrial facilities located in coastal areas subject to tsunami hazards may be at risk of tsunami impact and damage. Furthermore, if hazardous materials are present these can be accidentally released impacting nearby residents and dispersing into the environment. In this report we present the results of a study which analyzed the potential impact of two tsunamis originating in the Tyrrhenian Sea and their consequences at an industrial facility located on the coast in north-eastern Sicily. The results of the tsunami simulations indicate that in both scenarios there would be eighteen storage tanks (of 43 located within 400 m from the shoreline) at the industrial facility subject to flooding, with tanks closer to the shoreline suffering up to 0.8 m inundation. Flow velocities in most areas are less than 1 m/s. This indicates that any damage would occur due to hydrostatic uplift forces due to buoyancy particularly in the western part of the facility where inundation levels are higher and storage tanks are less protected. Potential damage caused by impact of floating debris may be a problem in an area near the shoreline just west of a pumping station and warehouse (central section of the refinery near the shoreline) due to high flow velocities (3-4 m/s) in both tsunami scenarios. Foundation soils and foundation systems could also be at risk from shear- and liquefaction-induced scour in this section of the plant. The likelihood for hazardous materials releases from inundated storage tanks is low but could occur due to breakage of connected pipelines and flanges due to buoyancy, or due to floating off of almost empty storage tanks and connected pipelines. Flooding of electrical equipment, such as control panels, pumps, and motors not raised above the inundation level could result in salt water intrusion leading to possible short circuit, hampering of safety and mitigation systems, process upsets and possible hazardous materials releases. We conclude however that in the two scenarios studied, the consequences of potential hazardous materials releases, fires or explosions triggered by the tsunamis on nearby residents and neighbouring facilities are likely to be small. Nevertheless, we make recommendations for preventive and preparedness measures that can be taken to reduce the risk of tsunami-triggered Natech accidents and to mitigate their consequences if they do occur.JRC.G.7-Traceability and vulnerability assessmen

Assessment of Interpolation Methods for EFAS

The observed meteorological inputs for the European Flood Alert System (EFAS) have been analysed. Observed sources are: 1) Grid and Station data collected from the MARS-STAT data base, 2) high resolution rainfall and mean temperature data covering Germany and upper Danube (HR). Several interpolation methods have been calibrated and cross validated. The comparisons of the different interpolated data sources are discussed and the “best” interpolation method and parameters are suggested. The software station2map [3] is used to cross validate the different interpolation methods.JRC.H.7-Land management and natural hazard

29 September 2009 Samoa Tsunami

On 29 September 2009 at 17:48:11 UTC a large earthquake of magnitude 8 struck off-shore of the Samoa Islands and generated a large tsunami that destroyed several villages and caused more than 160 fatalities. This report first presents the characteristics of the earthquake and discusses the best estimations for the fault parameters. These are necessary input data for the hydrodynamic tsunami calculations. Then, a comparison between the near-real time systems and the post-event calculations is performed, with an analysis of the observed differences compared with observed tidal measurements. Coarse, detailed and very detailed calculations are presented in order to identify areas of maximum damage. Conclusions are drawn for improvements in the near-real time system.JRC.G.2-Global security and crisis managemen

Tropical Cyclone ISAAC. USA, August 2012

Tropical Cyclone ISAAC, after causing damage and deaths in Haiti, moved towards the coast of SE Louisiana (USA), where it made two landfalls. After the second landfall, it started moving inland in SE Louisiana, passing W of New Orleans on Aug 29 afternoon/evening (UTC), weakening into a tropical storm, then late on Aug 30 became a tropical depression. Tropical Cyclone ISAAC affected the southern parts of Louisiana, Mississippi and Alabama with heavy rainfall, strong winds and storm surge, causing flooding, power outages, damage to property and, according to media report, killing at least 7 people. Most of this damage has been caused by heavy rains and storm surge. The Joint Research Centre (JRC) followed the event through the information automatically collected and analysed in the Global Disasters Alerts and Coordination System (GDACS). GDACS classification, for TC ISAAC in the USA, was: Green for the wind impact, Orange for rain impact and Red for storm surge impact. On 27 August 2012, 2 days before the landfall, the JRC HyFlux2 storm surge model indicated a possible storm surge in the order of 2.5-3.5m for Aug 29 morning (UTC) in the coastal area E-SE of New Orleans, Louisiana Online observations and NOAA reports confirmed the forecasts. This report analyses and discusses the GDACS automatic impact assessments and compares the JRC HyFlux2 deterministic storm surge forecasts with the probabilistic forecasts provided by NOAA.JRC.G.2-Global security and crisis managemen

Third Generation Tsunami scenario matrix for the Portuguese Tsunami Early Warning System

In Portugal, the Instituto de Meteorologia (IM) is the institution responsible for the Portuguese seismic network and it is the candidate to host the Portuguese Tsunami Warning System. One critical component of the system is the scenario database and the Tsunami Analysis Tool that help the operator to take decisions during the course of the event. This paper describes the progress done since 2008 conducting to the 3rd generation of the scenario database that provides a higher resolution modeling at the coastline for the whole North Atlantic. The 3rd generation scenarios are initiated by a simulation domain with a coarse bathymetry cell size (2 min). This initial calculation establishes the adequate initial and boundary conditions to 3 other domain calculations with a much finer cell size (0.25 min). The high-resolution calculation is performed only close to the coast in order to reduce the CPU time.JRC.G.2-Global security and crisis managemen

Tropical Cyclone GIOVANNA. Madagascar, February 2012

JRC has developed GDACS, an early warning system created to alert the humanitarian community about potential disasters which are under development. Tropical cyclones are some of the most damaging events, affecting the coastal population with three dangerous effects: strong wind, heavy rain and storm surge. GDACS includes the analysis of the first and the second effects, and recently also the third effect (storm surge) has been implemented. An impact assessment for all the three alerts are presented in the report. Wind alert level estimated by GDACS was Red, due to the high wind and the high vulnerability of the affected country. The wind impact assessment by BNGRC has confirmed that most of the damage due to Giovanna was caused by strong winds. The region most affected has been Antisanana. The rain impact alert level in GDACS is based on the estimation of the total accumulation of rainfall on land using NOAA eTRaP data. The applicability of the data was considered fine for alert levels at regional level, but not at local level due to spatial uncertainty. The storm surge GDACS alert level is based on the calculations of the JRC code HyFlux2. The accuracy of the estimated storm surge height could not be established because the available tide gauge was malfunctioning. We compared our results with two UNOSAT/UNITAR impact assessment maps of two damaged cities (Brickaville and Vatomadry). These maps gave a clear indication of building damages, as a result of strong winds and storm surge while the JRC calculations showed a storm surge in the order of 1 m. Overall, the GDACS models performed well. Alert levels for all hazard components were consistent with the observed impact. The location and timing of the information could accurately identify the affected provinces. GDACS information is appropriate for near real-time strategic decision making.JRC.G.2-Global security and crisis managemen