Nat Hazards Research Articles

A co-design method for including stakeholder perspectives in nature-based flood risk management

Intervention methods to establish commitment to (collaborative) action are of potential interest to researchers and policymakers intent upon including stakeholder perspectives in natural risk governance (Scolobig, Nat Hazards 81:27–43, 2016). In this paper, a 6-step co-design method for engaging with local people in collaboratively envisioning nature-based solutions for flood defence is described. The problem structuring base of the participatory method is extended to accommodate the multi-actor situation and the local context of flood risk management. The intervention method is applied in a workshop in the Houston–Galveston Bay area in October 2014. At that time there was strong contestation surrounding the proposed Ike Dike with alternative combinations of nature-based and smaller conventional engineering solutions being proposed. The results indicate that the local participants were able to envision a wide range of future outcomes for the bay and were able to use the insights on nature-based solutions and the social contacts that they acquired at the transdisciplinary workshop to mobilize commitment to joint action. This action focused on collaboration rather than specifying ecological or technical infrastructural requirements and was instrumental in initiating more open discourse on flood defence options for the Houston–Galveston Bay area. The paper concludes that the generic applicability of the co-design method is limited by the requirement to understand and accommodate local circumstances and participants’ insights within the workshop.

Probable maximum tropical cyclone parameters for east and west coast of India

In this discussion, the authors will demonstrate that the large discrepancy of results in Kumar et al. (Nat Hazards 1–19, 2022) using different fitting methods is a cause of inappropriate implementation of some methods. The authors will also show the significant overestimate of the higher return period wind speeds using the basin-wide maximum sustained wind speeds compared to the results using simulations.

Harmful diatoms and dinoflagellates in the Indian Ocean: a study from Southern coast of Sri Lanka

Harmful diatoms and dinoflagellates in the Indian Ocean: a study from Southern coast of Sri Lanka

Discussion of “Consequences of dike breaches and dike overflow in a bifurcating river system” by Anouk Bomers, Ralph M. J. Schielen and Suzanne J. M. H. Hulscher

In this discussion, the authors will point out that even if Bomers et al. (Nat Hazards 97:309–334, 2019) tackle an important problem, ignoring the uncertainties related to the roughness coefficients, Manning coefficients, the downstream boundary and most importantly the errors of the chosen software, HEC-RAS, are serious shortcomings of their study.

Coastal inundation due to tropical cyclones along the east coast of India: an influence of climate change impact

Coastal inundation due to storm tides is computed using ADvanced CIRCulation (ADCIRC) model along the east coast of India. Inland inundation due to storm tides is calculated every 10 km along the coast by using synthetic tracks as described in Rao et al. (Nat Hazards, 2019. https://doi.org/10.1007/s11069-019-03804-z). The cyclonic winds are computed using a maximum pressure drop of the cyclone based on a 100-year return period. The coast is mapped for the maximum possible extent of inland inundation with water levels at the district level. The influence of climate change impact as a result of global warming on the coastal inundation is evaluated by enhancing the intensity of the cyclones. Peak water levels of about 10–12 m are found along the north of Odisha coast. The most vulnerable region in terms of coastal inundation in the present scenario is found in the districts of West Bengal; however, they are the least affected by about 5–6% due to climate change scenario (CCS). The most affected inundated districts by more than 50% due to CCS are observed in the Godavari deltaic region in Andhra Pradesh. Though the water levels in the Ramanathapuram District in Tamil Nadu reach more than 8 m in any scenario, the region is unaffected by the coastal inundation due to high local topography. By examining the inundated area of different water levels, it is revealed that more than 75% of the total area is inundated with greater than 2 m water levels in the northern districts of Odisha and Ramanathapuram District in Tamil Nadu.

Comment on “An extended STIRPAT model-based methodology for evaluating the driving forces affecting carbon emissions in existing public building sector: evidence from China in 2000–2015” by Ma et al. (2017)

This contribution highlights that the paper presented by Ma et al. (Nat Hazards 89(2):741–756, 2017) presents VIF lower than 1 which does not coincide with the natural definition of VIF and clarifies how to detect collinearity after the application of the ridge estimator and how the results can be analyzed. Thus, this contribution allows empirical conclusions to be founded on a rigorously well-applied methodology.

Extreme events: a framework for assessing natural hazards

The two-step framework for over-threshold modelling of environmental extremes proposed in Bernardara et al. (Nat Hazards Earth Syst Sci 14:635–647, 2014) for univariate analyses is generalized to an event-based framework applicable to multivariate analyses. The distinction between sequential values (temporal observations at a given time step) and the event-describing values (such as storm peaks in univariate Peaks-Over-Threshold extrapolations) is further detailed and justified. The classification of multivariate analyses introduced in Mazas and Hamm (Coast Eng 122:44–59, 2017) is refined and linked to the meaning of the concepts of event, sampling and return period that is thoroughly examined, their entanglement being highlighted. In particular, sampling is shown to be equivalent to event definition, identification and description. Event and return period definition are also discussed with respect to the source phenomena or to response (or structure) phenomena. The extreme event approach is thus proposed as a comprehensive framework for univariate and multivariate analyses for assessing natural hazards, seemingly applicable to any field of environmental studies.

Statistical model for earthquake economic loss estimation using GDP and DPI: a case study from Iran

As earthquakes can result in multi-dimensional negative consequences such as human loss and building damage, the ability to make accurate economic loss estimations immediately after the occurrence is crucial. Unfortunately, in many earthquake-stricken countries such as Iran, governments are often unable to quickly or accurately assess post-earthquake losses. The aim of this paper, therefore, is to extend the model developed by Chan et al. (Nat Hazards 17:269–283, 1998) to two independent variables to develop an earthquake economic loss estimation method based on the economic and socio-economic indices gross domestic product (GDP) and disposable personal income (DPI) and a seismic hazard probability function. A global cell map is also considered to assess the GDP and DPI based on the population in each cell affected by the earthquake. In the final stage, using the Modified Mercalli Intensity Scale, 18 earthquake damaged areas in Iran are taken as case study to estimate the economic losses using the new model presented in this paper.

Seismic activity characteristics in the East Sea area

Seismic activity characteristics in the East Sea area

Seismic status in Bangladesh

Seismic status in Bangladesh

PSHA in Israel by using the synthetic ground motions from simulated seismicity: the modified SvE procedure

In this study, we updated and modified the SvE approach of Shapira and van Eck (Nat Hazards 8:201–215, 1993) which may be applied as an alternative to the conventional probabilistic seismic hazard assessment (PSHA) in Israel and other regions of low and moderate seismicity where measurements of strong ground motions are scarce. The new computational code SvE overcomes difficulties associated with the description of the earthquake source model and regional ground-motion scaling. In the modified SvE procedure, generating suites of regional ground motion is based on the extended two-dimensional source model of Motazedian and Atkinson (Bull Seism Soc Amer 95:995–1010, 2005a) and updated regional ground-motion scaling (Meirova and Hofstteter, Bull Earth Eng 15:3417–3436, 2017). The analytical approach of Mavroeidis and Papageorgiou (Bull Seism Soc Amer 93:1099–1131, 2003) is used to simulate the near-fault acceleration with the near-fault effects. The comparison of hazard estimates obtained by using the conventional method implemented in the National Building Code for Design provisions for earthquake resistance of structures and the modified SvE procedure for rock-site conditions indicates a general agreement with some perceptible differences at the periods of 0.2 and 0.5 s. For the periods above 0.5 s, the SvE estimates are systematically greater and can increase by a factor of 1.6. For the soft-soil sites, the SvE hazard estimates at the period of 0.2 s are greater than those based on the CB2008 ground-motion prediction equation (GMPE) by a factor of 1.3–1.6. We suggest that the hazard estimates for the sites with soft-soil conditions calculated by the modified SvE procedure are more reliable than those which can be found by means of the conventional PSHA. This result agrees with the opinion that the use of a standard GMPE applying the NEHRP soil classification based on the Vs, 30 parameter may be inappropriate for PSHA at many sites in Israel.

Assessment of earthquake-induced liquefaction hazard in urban areas of Hanoi city using LPI-based method

Assessment of earthquake-induced liquefaction hazard in urban areas of Hanoi city using LPI-based method

Simulation of Strong Ground Motion of the 2009 Bhutan Earthquake Using Modified Semi-Empirical Technique

On 21st September 2009 an earthquake of magnitude (M w 6.1) occurred in the East Bhutan. This earthquake caused serious damage to the residential area and was widely felt in the Bhutan Himalaya and its adjoining area. We estimated the source model of this earthquake using modified semi empirical technique. In the rupture plane, several locations of nucleation point have been considered and finalised based on the minimum root mean square error of waveform comparison. In the present work observed and simulated waveforms has been compared at all the eight stations. Comparison of horizontal components of actual and simulated records at these stations confirms the estimated parameters of final rupture model and efficacy of the modified semi-empirical technique (Joshi et al., Nat Hazards 64:1029–1054, 2012b) of strong ground motion simulation.

Segmentation of Main Boundary Thrust and Main Central Thrust in Western Himalaya for assessment of seismic hazard by Mridula et al., Nat Hazards (2016) 84: 383–403

Mridula et al. (Nat Hazards 84:383–403, (2016) have tried to identify segments of two major thrust faults, the Main Boundary Thrust and Main Central Thrust, in Western Himalaya. This was done by using seismological and tectonic data where various patterns have been recognized. However, the study has used uncorrected seismological data to recognize patterns. This has serious limitations because the seismological data have huge errors with depth, which should be corrected before any pattern can be recognized. Since the earthquake data have not been corrected for depth, it is impossible to plot them on a tectonic map and to assign them to a particular fault. Such an exercise is possible only if the earthquake events are relocated for both depth and location. Further, the authors have used very old tectonic map, which has not been updated, and often the faults are not properly mapped as could be seen on the latest tectonic and topographic maps available. Thus, we aim to initiate a discussion on this and offer solutions which could improve the paper and give an opportunity for authors to rethink over their work.

Four loss estimates for the Gorkha M7.8 earthquake, April 25, 2015, before and after it occurred

The number of fatalities in the Gorkha M7.8 earthquake of April 25, 2015, has been estimated at four different times as follows. In March 2005, the fatality estimate in this journal was 21,000–42,000 with an assumed magnitude of 8.1 (Wyss in Nat Hazard 34:305–314, 2005). Within hours after this earthquake, the estimated number of fatalities by QLARM was 2000–10,000 using a point source model and M7.9. Four hours later, the estimate was 20,000–100,000, based on a first approximation line source model and assuming children were in school. Children out of school, as this was a weekend day, reduced the fatalities by approximately a factor of two, but was not taken into account for the calculation. The final line source estimates based on M7.8 and M7.9 calculates 800–9300 and 1100–11,200 fatalities, respectively. The official count is about 10,000 fatalities. These estimates were performed using QLARM, a computer tool and world data set on the distribution of people in settlements and containing a model of the buildings present. It is argued here that the loss estimate 10 years before the event being within a factor of 2.1 of the eventual loss count is useful for mitigation planning. With varying quality of information on the source and the attenuation, the estimates of fatalities shortly after the earthquake are accurate enough to be useful for first responders. With full knowledge of the rupture properties and the regional attenuation of seismic waves, the numbers of human losses are estimated correctly.

A numerical study of the impact of hurricane-induced storm surge on the Herbert Hoover Dike at Lake Okeechobee, Florida

Hurricanes Frances, Jeanne, and Wilma passed over Lake Okeechobee, Florida, in September 2004 and October 2005, respectively. Strong winds caused a large surface seiche on the lake during all three storms. These storms resulted in erosion damage to the Herbert Hoover Dike (HHD) on Lake Okeechobee. In this paper, we use the Fully Adaptive Storm Tide (FAST) model (Kelly et al. in Coast Eng J 57(4):1–30, 2015, Nat Hazards 83:53–74, 2016) to study the response of the lake (in terms of the water level fluctuations and induced currents) to hurricanes Frances, Jeanne, and Wilma. Comparisons of the modeled surface water level with the observations are in overall good agreement for all three hurricanes. The modeled results suggest that the strong currents induced by the storm winds may be the dominant factor controlling the dike erosion observed at the lake side. The locations of erosion damage to the dike are consistent with the modeled high velocity zones during these three storms. In addition, numerical experiments have been conducted with eight hypothetical category 5 hurricanes approaching from different directions to investigate the erosion-prone zones related to high velocities in the vicinity of the dike. The results of the study should help to provide insight into vulnerable reaches of the HHD and inform flood control in the Okeechobee region.

Effect of gravel content on creep behavior of clayey soil at residual state: implication for its role in slow-moving landslides

Soil creep is mostly manifested in slow-moving landslides. It is often the case for active slow-moving landslide with slip zone comprising clayey soil where creep would develop in the residual condition. If gravel is presented in clayey soil, this will have considerable impact on creep behavior of clayey soil. However, knowledge about creep behavior of the clayey soil containing gravel particles is scarce. This paper discusses creep behavior of natural clayey soil with gravel at residual state through a series of creep shear tests. Soil samples for this testing program were collected from the slip zones of two large slow-moving landslides in China. The collected soil samples consisted of clayey soil containing various amounts of gravel particles. The test results show that the soil specimens underwent two different creep patterns. An attenuating creep pattern was observed when the soil specimens were subjected to creep stress less than the residual strength, and a creep with increasing strain rate, or a nonattenuating creep pattern, with no evident secondary creep was noted when creep stress was intestinally increased to a level slightly greater than the residual strength. The creep patterns of clayey soil with gravel at the residual state observed in this study were noted to be very consistent with those of the gravel-free clayey soil reported in Bhat et al. (Int J Geomater 1(1):39–43, 2011, Nat Hazards 69(3):2161–2178, 2013) and Di Miao et al. (Eng Geol 162:53–66, 2013). This gives an indication that creep patterns of clayey soils with and without gravel at the residual state are essentially the same, or in other words, that the presence of gravel does not change the creep pattern of clayey soil. However, the test results in this study illustrate that the presence of gravel does have a notable effect on creep behavior of clayey soil. Specifically, the creep stress leading to creep failure of clayey soil and the minimum ratio of the creep stress to residual strength (RCSR) increased with gravel content, and the displacement until the tertiary creep was also larger in samples containing more gravel particles. It is postulated that creep behavior of clayey soil at the residual state in this study and its relationship with gravel content may be related to strength recovery and crushing of gravel-sized particles during creep.

Use of GIS in assessing building vulnerability for landslide hazard in The Nilgiris, Western Ghats, India

The present paper aims at to produce the building vulnerability and its spatial distribution in mountainous regions of the Nilgiris District in the Western Ghats, India. The landslide-susceptible areas were identified based on the existing landslide-susceptible maps. The landslide-prone slope was identified based on the historical and recent landslide information’s collected from various authenticated sources as well as the field investigations made on the recent landslides. The high-to-severe landslide hazard-prone areas were selected for the present study of building vulnerability analysis. The areas were divided into ten segments based on the landslide inventory, built-up areas, and transportation corridors in the vicinity of landslide locations. Building foot print map was prepared for each segments using ArcGIS software visual interpretation for 1627 buildings and infrastructures. Different thematic layers viz, building type/material, surrounding wall, sloping side details, warning, and number of floors which contribute to landslide vulnerability in vector formats are used for the present study. Using the formula proposed by Papathoma-Kohle et al. (Nat Hazards Earth Syst Sci 7:765–779, 2007) the vulnerability score were calculated by scripting in ArcGIS software. Based on the vulnerability score, the buildings were grouped under three categories viz, low, medium, and high vulnerability. The spatial distribution of vulnerability of buildings was prepared and presented. The present study can be useful data for preparation of regional landuse plan as well as evacuation plans and warning systems to safeguard measure for population living in the vulnerable buildings in The Nilgiris District of Western Ghats in India.

Mapping the earthquake-induced landslide hazard around the main oil pipeline network of the Agri Valley (Basilicata, southern Italy) by means of two GIS-based modelling approaches

This study presents a first-level spatial assessment of the susceptibility to earthquake-induced landslides in the seismic area of the Agri Valley (Basilicata Region, southern Italy), which hosts the largest onshore oilfield and oil/gas extraction and pre-treatment plant in Europe and is the starting point of the 136-km-long pipeline that transports the plant’s products to the refinery located in Taranto, on the Ionian seacoast. Two methodologies derived from the ones proposed by Newmark (Geotechnique 15(2):139–159, 1965) and Rapolla et al. (Eng Geol 114:10–25, 2010, Nat Hazards 61:115–126, 2012. doi: 10.1007/s11069-011-9790-z), based on different modelling approaches, were implemented using the available geographic information system tools, which allowed a very effective exploitation of the two models capability for regional zoning of the earthquake-induced landslide hazard. Subsequently, the results obtained from the two models were compared by both visual evaluation of thematic products and statistical correlation analysis of quantitative indices, such as the Safety Index based on the Newmark’s approach and the Susceptibility Index from Rapolla’s model. The comparison showed a general agreement in highlighting the most critical areas. However, some slight differences between the two models’ results were observed, especially where rock materials and steep slopes are prevailing.

Reply to discussion of “Extreme streamflow drought in the Karkheh river basin (Iran): probabilistic and regional analyses”

In our original paper (Nat Hazards 76:327–346, 2015. doi:10.1007/s11069-014-1492-x), we analyzed hydrological droughts based on the minimum values of the streamflow drought index at different time scales using L-moments. In this paper, we highlight the importance of the magnitude and type of selected drought index for regional frequency analysis and discuss the validity of results only for station clusters considered in response to the commentary by Bahmani and Khorsandi (Nat Hazards, 2015. doi:10.1007/s11069-015-1830-7).