ALBERT

Description: Scenario based approach for multiple source Tsunami Hazard assessment for Sines, Portugal Natural Hazards and Earth System Sciences Discussions, 3, 4663-4693, 2015 Author(s): M. Wronna, R. Omira, and M. A. Baptista In this paper, we present a scenario-based approach for tsunami hazard assessment for the city and harbour of Sines – Portugal, one of the test-sites of project ASTARTE. Sines holds one of the most important deep-water ports which contains oil-bearing, petrochemical, liquid bulk, coal and container terminals. The port and its industrial infrastructures are facing the ocean southwest towards the main seismogenic sources. This work considers two different seismic zones: the Southwest Iberian Margin and the Gloria Fault. Within these two regions, we selected a total of six scenarios to assess the tsunami impact at the test site. The tsunami simulations are computed using NSWING a Non-linear Shallow Water Model With Nested Grids. In this study, the static effect of tides is analysed for three different tidal stages MLLW (mean lower low water), MSL (mean sea level) and MHHW (mean higher high water). For each scenario, inundation is described by maximum values of wave height, flow depth, drawback, runup and inundation distance. Synthetic waveforms are computed at virtual tide gauges at specific locations outside and inside the harbour. The final results describe the impact at Sines test site considering the single scenarios at mean sea level, the aggregate scenario and the influence of the tide on the aggregate scenario. The results confirm the composite of Horseshoe and Marques Pombal fault as the worst case scenario. It governs the aggregate scenario with about 60 % and inundates an area of 3.5 km 2 .

Description: A numerical study of the early stages of a tropical cyclogenesis in relation to the MJO Natural Hazards and Earth System Sciences Discussions, 3, 4919-4935, 2015 Author(s): J. Guerbette, M. Plu, C. Barthe, and J.-F. Mahfouf The role of an active phase of the Madden–Julian Oscillation (MJO) on the evolution of a mesoscale convective systems (MCS) leading to a tropical depression is investigated in the South-West Indian Ocean during the Dynamics of the Madden–Julian Oscillation (DYNAMO) field experiment, with a numerical limited-area atmospheric model. A mesoscale vortex is followed in the low-troposphere from the initiation of the active MJO phase. It is shown that the interaction of the vortex with the Equatorial jet associated with the MJO plays an important role on the vortex development. As the vortex encounters the southern part of the low-level jet, it undergoes intensification that is explained by the barotropic conversion of kinetic energy from the low-level jet to the vortex.

Description: The 9 September 2010 torrential rain and flash flood in the Dragone catchment, Atrani, Amalfi Coast (Southern Italy) Natural Hazards and Earth System Sciences Discussions, 3, 4715-4751, 2015 Author(s): C. Violante, G. Braca, E. Esposito, and G. Tranfaglia In this paper we use a multi-hazard approach to analyse the 9 September 2010 flash-flood occurred in the Dragone basin, a 9 km 2 catchment located along the Amalfi rocky coastal range, Southern Italy. In this area, alluvial-fan-flooding is the most frequent and destructive geologic hazards since Roman time. Sudden torrent of waters (flash flood) are caused by high-intensity and very localized cloudbursts of short duration inducing slope erosion and sediment delivery from slope-to-stream. The elevated bed load transport produces fast-moving hyperconcentrated flows with significant catastrophic implications for communities living at stream mouth. The 9 September 2010 rainstorm event lasted 1 h with an intensity rainfall peak nearly to 120 mm h −1 . High topographic relief of the Amalfi coastal range and positive anomalies of the coastal waters conditioned the character of the convective system. Based on geological data and post-event field evidence and surveys, as well as homemade-videos, and eyewitness accounts the consequent flash-flood mobilized some 25 000 m 3 of materials with a total (water and sediment) peak flow of 80 m 3 s −1 . The estimated peak discharge of only clear water was about 65 m 3 s −1 . This leads to a sediment bulking factor of 1.2 that corresponds to a flow with velocities similar to those of water during a flood.

Description: Teaching disaster preparedness via a mobile device: a study of Auckland Civil Defence's Smartphone Application Natural Hazards and Earth System Sciences Discussions, 3, 4555-4583, 2015 Author(s): O. Kulemeka This content analysis study examined whether a disaster preparedness education smartphone application created by a New Zealand city matches what experts say are effective ways of teaching disaster preparedness and teaching via an app. The app was assessed to ascertain if it excelled as a platform for learning, communicated effectively, addressed factors that can hinder people from preparing, and provided information for special needs populations. Results show that the app addressed most factors that hinder preparedness, provided information for some special needs populations, excelled as a platform for learning, and communicated effectively. The app's weaknesses include the fact that it lacked targeted information for low-income residents. The findings provide insight on how organizations can effectively use apps to teach disaster preparedness. The author passed away before the publication of this discussion paper. Therefore, a final revised paper is not foreseen.

Description: Inversion kinematics at deep-seated gravity slope deformations: a paleoseismological perspective Natural Hazards and Earth System Sciences Discussions, 3, 4585-4617, 2015 Author(s): F. Pasquarè Mariotto and A. Tibaldi We compare data from three deep-seated gravity slope deformations (DSGSDs) where paleoseismological techniques were applied in artificial trenches. At all trenches, located in metamorphic rocks of the Italian Alps, there is evidence of extensional deformation given by normal movements along slip planes dipping downhill or uphill, and/or fissures, as expected in gravitational failure. However, we document and illustrate – with the aid of trenching – the evidence of reverse movements. The reverse slips occurred mostly along the same planes along which normal slip occurred, and produced drag folds in unconsolidated Holocene sediments as well as the superimposition of substrate rocks on Holocene sediments. Since trenches are located in different positions with respect to the slope affected by the DSGSD, it is possible to suggest that reverse slip might occur both at the toe portions of DSGSDs and in their central-upper portions. When the age relationships between the two deformation kinematics can be sorted out, they clearly indicate that reverse slips postdate normal ones. Our data suggest that during the development of long-lived DSGSDs, inversion kinematics may occur in different sectors of the unstable rock mass. The inversion is interpreted as either due to locking of the frontal blocks of a DSGSD, or the relative decrease in the rate of downward movement in the frontal blocks with respect to the rear blocks.

Description: Factors of subjective heat stress of urban citizens in contexts of everyday life Natural Hazards and Earth System Sciences Discussions, 3, 4619-4661, 2015 Author(s): T. Kunz-Plapp, J. Hackenbruch, and J. W. Schipper Heat waves and the consequent heat stress of urban populations have a growing relevance in urban risk management and strategies of urban adaptation to climate change. In this context, social science studies on subjective heat stress of urban citizens are a new emerging field. To contribute to the understanding of subjective heat stress and its major determinants in a daily life perspective, we conducted a questionnaire survey with 323 respondents in Karlsruhe, Germany, after a heat wave in July and August 2013. Statistical data analysis showed that heat stress is an issue permeating everyday activities. It was found that the subjective heat stress at home is lower than at work and in general. Subjective heat stress in general, at home, and at work was determined by the health impairments experienced during the heat and the feeling of being helplessly exposed to the heat. For heat stress at home, additionally characteristics of the residential building and the built environment played a role. Although the rate of implemented coping measures was rather high, coping measures showed no uniform effect for the subjective heat stress. The results furthermore show that coping with heat is performed within the scopes of action in daily life. We conclude that in terms of urban adaptation strategies, further research is needed to understand how various processes of daily social (work) life enable or limit individual coping and adaptation capacities and that communication strategies are important for building capacities to better cope with future heat waves.

Description: InSAR observations of the 2009 Racha earthquake, the Republic Georgia Natural Hazards and Earth System Sciences Discussions, 3, 4695-4714, 2015 Author(s): E. Nikolaeva and T. R. Walter Central Georgia is an area strongly affected by earthquake and landslide hazards. On 29 April 1991 a major earthquake ( M w = 7.0) struck the Racha region in the republic Georgia, followed by aftershocks and significant afterslip. The same region was hit by another major event ( M w = 6.0) on 7 September 2009. The aim of the study reported here was to utilize geodetic data as synthetic aperture radar interferometry (InSAR) to improve a knowledge about the spatial pattern of deformation due to the earthquakes in the seismic active central Georgia. There were no actual earthquake observations by InSAR in Georgia. We used the multi-temporal ALOS L-band InSAR data to produce interferograms spanning times before and after the 2009 earthquake. We detected a local uplift around 10 cm in the interferogram near the earthquake's epicenter whereas evidence of surface ruptures could not be found in the field along the active thrust fault. We simulated a deformation signal which could be created by the 2009 Racha earthquake on the basis of local seismic records and by using an elastic dislocation model. The observed InSAR deformation is in good agreement with our model. We compared our modeled fault surface of the September 2009 with the April 1991 Racha earthquake fault surfaces, and identify the same fault or a sub-parallel fault of the same system as the origin. The patch that was active in 2009 is just adjacent to the 1991 patch, indicating a possible mainly westward propagation direction, with important implications for future earthquake hazards.

Description: Risk for large-scale fires in boreal forests of Finland under changing climate Natural Hazards and Earth System Sciences Discussions, 3, 4753-4795, 2015 Author(s): I. Lehtonen, A. Venäläinen, M. Kämäräinen, H. Peltola, and H. Gregow The target of this work was to assess the impact of projected climate change on the number of large forest fires (over 10 ha fires) and burned area in Finland. For this purpose, we utilized a strong relationship between fire occurrence and the Canadian fire weather index (FWI) during 1996–2014. We used daily data from five global climate models under representative concentration pathway RCP4.5 and RCP8.5 scenarios. The model data were statistically downscaled onto a high-resolution grid using the quantile-mapping method before performing the analysis. Our results suggest that the number of large forest fires may double or even triple during the present century. This would increase the risk that some of the fires could develop into real conflagrations which have become almost extinct in Finland due to active and efficient fire suppression. Our results also reveal substantial inter-model variability in the rate of the projected increase in forest-fire danger. We moreover showed that the majority of large fires occur within a relatively short period in May and June due to human activities and that FWI correlates poorer with the fire activity during this time of year than later in summer when lightning is more important cause of fires.

Description: Snow instability evaluation: calculating the skier-induced stress in a multi-layered snowpack Natural Hazards and Earth System Sciences Discussions, 3, 4833-4869, 2015 Author(s): F. Monti, J. Gaume, A. van Herwijnen, and J. Schweizer The process of dry-snow slab avalanche formation can be divided into two phases: failure initiation and crack propagation. Several approaches tried to quantify slab avalanche release probability in terms of failure initiation based on shear stress and strength. Though it is known that both the properties of the weak layer and the slab play a major role in avalanche release, most previous approaches only considered slab properties in terms of slab depth, average density and skier penetration. For example, for the skier stability index, the additional stress (e.g. due to a skier) at the depth of the weak layer is calculated by assuming that the snow cover can be considered a semi-infinite, elastic half-space. We suggest a new approach based on a simplification of the multi-layered elasticity theory in order to easily compute the additional stress due to a skier at the depth of the weak layer taking into account the layering of the snow slab and the substratum. We first tested the proposed approach on simplified snow profiles, then on manually observed snow profiles including a stability test and, finally, on simulated snow profiles. Our simple approach well reproduced the additional stress obtained by finite element simulations for the simplified profiles – except that the sequence of layering in the slab cannot be replicated. Once implemented into the classical skier stability index and applied to manually observed snow profiles classified into different stability classes, the classification accuracy improved with the new approach. Finally, we implemented the refined skier stability index into the 1-D snow cover model SNOWPACK. For the two study cases presented in this paper, this approach showed promising results even though further verification is still needed. In the future, we intend to implement the proposed approach for describing skier-induced stress within a multi-layered snowpack into more complex models which take into account not only failure initiation but also crack propagation.

Description: Partnerships for affordable and equitable disaster insurance Natural Hazards and Earth System Sciences Discussions, 3, 4797-4832, 2015 Author(s): J. Mysiak and C. D. Pérez-Blanco Extreme events are becoming more frequent and intense, inflating the economic damages and social hardship set-off by natural catastrophes. Amidst budgetary cuts, there is a growing concern on societies' ability to design solvent disaster recovery strategies, while addressing equity and affordability concerns. The participation of private sector along with public one through Public-Private Partnerships (PPPs) has gained on importance as a means to address these seemingly conflicting objectives through the provision of (catastrophic) natural hazard insurance. This is the case of many OECD countries, notably some EU Member States such as the United Kingdom and Spain. The EU legislator has adapted to this new scenario and recently produced major reforms in the legislation and regulation that govern the framework in which PPPs for (catastrophic) natural hazard insurance develop. This paper has a dual objective: (1) review the complex legal background that rules the provision of insurance against natural catastrophes in the EU after these major reforms, (2) assess the implications of the reforms and offer concise Policy Guiding Principles.

Description: Integrated statistical modelling of spatial landslide probability Natural Hazards and Earth System Sciences Discussions, 3, 5677-5715, 2015 Author(s): M. Mergili and H.-J. Chu Statistical methods are commonly employed to estimate spatial probabilities of landslide release at the catchment or regional scale. Travel distances and impact areas are often computed by means of conceptual mass point models. The present work introduces a fully automated procedure extending and combining both concepts to compute an integrated spatial landslide probability: (i) the landslide inventory is subset into release and deposition zones. (ii) We employ a simple statistical approach to estimate the pixel-based landslide release probability. (iii) We use the cumulative probability density function of the angle of reach of the observed landslide pixels to assign an impact probability to each pixel. (iv) We introduce the zonal probability i.e. the spatial probability that at least one landslide pixel occurs within a zone of defined size. We quantify this relationship by a set of empirical curves. (v) The integrated spatial landslide probability is defined as the maximum of the release probability and the product of the impact probability and the zonal release probability relevant for each pixel. We demonstrate the approach with a 637 km 2 study area in southern Taiwan, using an inventory of 1399 landslides triggered by the typhoon Morakot in 2009. We observe that (i) the average integrated spatial landslide probability over the entire study area corresponds reasonably well to the fraction of the observed landside area; (ii) the model performs moderately well in predicting the observed spatial landslide distribution; (iii) the size of the release zone (or any other zone of spatial aggregation) influences the integrated spatial landslide probability to a much higher degree than the pixel-based release probability; (iv) removing the largest landslides from the analysis leads to an enhanced model performance.

Description: Atmospheric circulation patterns, cloud-to-ground lightning, and locally intense convective rainfall associated with debris flow initiation in the Dolomite Alps of northeastern Italy Natural Hazards and Earth System Sciences Discussions, 3, 5717-5775, 2015 Author(s): S. J. Underwood, M. D. Schultz, M. Berti, C. Gregoretti, A. Simoni, T. L. Mote, and A. M. Saylor The Dolomite Alps of northeastern Italy experience debris flows with great frequency during the summer months. An ample supply of unconsolidated material on steep slopes and a summer season climate regime characterized by recurrent thunderstorms combine to produce an abundance of these destructive hydrogeologic events. In the past debris flow events have been studied primarily in the context of their geologic and geomorphic characteristics. The atmospheric contribution to these mass wasting events has been limited to recording rainfall and developing intensity thresholds for debris mobilization. This study aims to expand the examination of atmospheric processes that preceded both locally intense convective rainfall (LICR) and debris flows in the Dolomite region. 500 hPa pressure level plots of geopotential heights were constructed for a period of three days prior to debris flow events to gain insight into the synoptic scale processes which provide an environment conducive to LICR in the Dolomites. Cloud-to-ground (CG) lightning flash data recorded at the meso-scale were incorporated to assess the convective environment proximal to debris flow source regions. Twelve events were analyzed and from this analysis three common synoptic scale circulation patterns were identified. Evaluation of CG flashes at smaller spatial and temporal scales illustrated that convective processes vary in their production of CG flashes (total number) and the spatial distribution of flashes can also be quite different between events over longer periods. During the 60 min interval immediately preceding debris flow a majority of cases exhibited spatial and temporal collocation of LICR and CG flashes. Also a number of CG flash parameters were found to be significantly correlated to rainfall intensity prior to debris flow initiation.

Description: Best index related to the shoreline dynamics during a storm: the case of Jesolo beach Natural Hazards and Earth System Sciences Discussions, 3, 7089-7134, 2015 Author(s): R. Archetti, A. Paci, S. Carniel, and D. Bonaldo The paper presents an application of shoreline monitoring aimed to understand the response of a beach to single storms and to identify its typical behaviour, in order to be able to predict shoreline changes and to properly plan the defence of the shore zone. On the study area, in Jesolo beach (Nothern Adriatic sea, Italy), a video monitoring station and an acoustic wave and current profiler were installed in spring 2013, recording respectively images and hydrodynamic data. The site lacks of previous detailed hydrodynamic and morphodynamics data. Variations in the shoreline were quantified in combination with available nearshore wave conditions, making it possible to analyse a relationship between the shoreline displacement and the wave features. Results denote characteristic patterns of beach response to storm events, and highlight the importance of improving beach protection in this zone, notwithstanding the many interventions experimented in the last decades. A total of 31 independent storm events were selected during the period October 2013–October 2014, and for each of them synthetic indexes based on storm duration, energy and maximum wave height were developed and estimated. It was found that the mean shoreline displacements during a storm are well correlated with the total wave energy during the considered storm by an empirical power law equation. A sub-selection of storms on beach protected by artificial dunes (in winter season) was examined in detail; we can conclude that the extensive adoption of artificial dunes in the study area was useful in the past also to reduce shoreline retreat during the storm. This type of interventions can sometimes contribute to prolonged overall stability not only in the replenished zone but also in down drift areas. The implemented methodology, which confirms to be economically attractive if compared to more traditional monitoring systems, proves to be a valuable system to monitor beach erosive processes and provide detailed indications on how to better plan beach maintenance activities. The presented methodology and the proposed results can therefore be used as a basis for improving the collaboration between coastal scientists and managers to solve beach erosion problems, in a location where data are seldom.

Description: Evaluation of the initial stage of the reactivated Cotopaxi volcano – analysis of the first ejected fine-grained material Natural Hazards and Earth System Sciences Discussions, 3, 6947-6976, 2015 Author(s): T. Toulkeridis, C. R. Arroyo, M. Cruz D'Howitt, A. Debut, A. V. Vaca, L. Cumbal, F. Mato, and E. Aguilera Fine-grained volcanic samples were collected at different locations near the Cotopaxi volcano on the same day of its reactivation and some days afterwards in August 2015. The wind-directions charged with such materials have been determined and compared with the existing data-base allowing preventive measures about local warning. The obtained data yielded the less expected wind-directions and therefore ash precipitation in usually less affected areas towards the northern and eastern side of Cotopaxi volcano. The collected samples were studied basically for their morphology, content in minerals and rock fragments as well as the chemical composition. The results obtained from this study allowed to identify and classify the origin of the expelled material being hydroclasts of andesites and dacites with rare appearances of rhyodacites and associated regular as well as accessory minerals all being present in the conduct and crater forming part of previous eruptive activities of the volcano. A further evaluation has been performed to determine the activity stage of the volcanic behavior. The resulting interpretation appears to point to a volcanic behavior a more frequent sporadic event with a relatively low probability of lahar generation rather than any other known destructive phase, which includes a less-frequent but tremendously more catastrophic scenario.

Description: The quantitative estimation of the vulnerability of brick and concrete building impacted by debris flow Natural Hazards and Earth System Sciences Discussions, 3, 5015-5044, 2015 Author(s): J. Zhang, Z. X. Guo, D. Wang, and H. Qian There is little historic data about the vulnerability of the damage elements in debris flow disaster in China. Therefore, it is difficult to estimate the vulnerability of debris flow quantitatively. This paper was devoted to the research of the vulnerability of brick and concrete building impacted by debris flow which widely existed in affected area. Under two assumptions, several prototype walls of brick and concrete were constructed to simulate the damaged structures in debris flow while the iron spheres were taken as the substitute of debris flow. The failure criterion of brick and concrete building was proposed with referring to the structure standards (brick and concrete) and the damage pattern in debris flow. The quantitatively estimation of vulnerability of brick and concrete building was finally established based on Fuzzy mathematics and the proposed failure criterion. The results show that the maximum impact bending moment is the best fit to be the disaster-causing factor in vulnerability curve and formula. The experiments in this paper is the preliminary research on the vulnerability of the element impacted by debris flow. The method and conclusion will be useful for the quantitative estimation of the vulnerability in debris flow and also can be referred in other types of the vulnerable elements research.

Description: Combined fluvial and pluvial urban flood hazard analysis: method development and application to Can Tho City, Mekong Delta, Vietnam Natural Hazards and Earth System Sciences Discussions, 3, 4967-5013, 2015 Author(s): H. Apel, O. M. Trepat, N. N. Hung, D. T. Chinh, B. Merz, and N. V. Dung Many urban areas experience both fluvial and pluvial floods, because locations next to rivers are preferred settlement areas, and the predominantly sealed urban surface prevents infiltration and facilitates surface inundation. The latter problem is enhanced in cities with insufficient or non-existent sewer systems. While there are a number of approaches to analyse either fluvial or pluvial flood hazard, studies of combined fluvial and pluvial flood hazard are hardly available. Thus this study aims at the analysis of fluvial and pluvial flood hazard individually, but also at developing a method for the analysis of combined pluvial and fluvial flood hazard. This combined fluvial-pluvial flood hazard analysis is performed taking Can Tho city, the largest city in the Vietnamese part of the Mekong Delta, as example. In this tropical environment the annual monsoon triggered floods of the Mekong River can coincide with heavy local convective precipitation events causing both fluvial and pluvial flooding at the same time. Fluvial flood hazard was estimated with a copula based bivariate extreme value statistic for the gauge Kratie at the upper boundary of the Mekong Delta and a large-scale hydrodynamic model of the Mekong Delta. This provided the boundaries for 2-dimensional hydrodynamic inundation simulation for Can Tho city. Pluvial hazard was estimated by a peak-over-threshold frequency estimation based on local rain gauge data, and a stochastic rain storm generator. Inundation was simulated by a 2-dimensional hydrodynamic model implemented on a Graphical Processor Unit (GPU) for time-efficient flood propagation modelling. All hazards – fluvial, pluvial and combined – were accompanied by an uncertainty estimation considering the natural variability of the flood events. This resulted in probabilistic flood hazard maps showing the maximum inundation depths for a selected set of probabilities of occurrence, with maps showing the expectation (median) and the uncertainty by percentile maps. The results are critically discussed and ways for their usage in flood risk management are outlined.

Description: Determination of rainfall thresholds for shallow landslides by a probabilistic and empirical method Natural Hazards and Earth System Sciences Discussions, 3, 3487-3508, 2015 Author(s): J. Huang, N. P. Ju, Y. J. Liao, and D. D. Liu Rainfall-induced landslides not only cause property loss, but also kill and injure large numbers of people every year in mountainous areas in China. These losses and casualties may be avoided to some extent with rainfall threshold values used in an early warning system at a regional scale for the occurrence of landslides. However, the limited availability of data always causes difficulties. In this paper we present a method to calculate rainfall threshold values with limited data sets for the two rainfall parameters: maximum hourly rainfall intensity and accumulated precipitation. The method has been applied to the Huangshan region, in Anhui Province, China. Four early warning levels (Zero, Outlook, Attention, and Warning) have been adopted and the corresponding rainfall threshold values have been defined by probability lines. A validation procedure showed that this method can significantly enhance the effectiveness of a warning system, and finally reduce the risk from shallow landslides in mountainous regions.

Description: Results comparison and model validation for flood loss functions in Australian geographical conditions Natural Hazards and Earth System Sciences Discussions, 3, 3823-3860, 2015 Author(s): R. Hasanzadeh Nafari, T. Ngo, and W. Lehman Rapid urbanisation, climate change and unsustainable developments are increasing the risk of floods, namely flood frequency and intensity. Flood is a frequent natural hazard that has significant financial consequences for Australia. The emergency response system in Australia is very successful and has saved many lives over the years. However, the preparedness for natural disaster impacts in terms of loss reduction and damage mitigation has been less successful. This study aims to quantify the direct physical damage to residential structures that are prone to flood phenomena in Australia. In this paper, the physical consequences of two floods from Queensland have been simulated, and the results have been compared with the performance of two selected methodologies and one newly derived model. Based on this analysis, the adaptability and applicability of the selected methodologies will be assessed in terms of Australian geographical conditions. Results obtained from the new empirically-based function and non-adapted methodologies indicate that it is apparent that the precision of flood damage models are strongly dependent on selected stage damage curves, and flood damage estimation without model validation results in inaccurate prediction of losses. Therefore, it is very important to be aware of the associated uncertainties in flood risk assessment, especially if models have not been adapted with real damage data.

Description: On the inclusion of GPS precipitable water vapour in the nowcasting of rainfall Natural Hazards and Earth System Sciences Discussions, 3, 3861-3895, 2015 Author(s): P. Benevides, J. Catalao, and P. M. A. Miranda The temporal behaviour of Precipitable Water Vapour (PWV) retrieved from GPS delay data is analysed in a number of case studies of intense precipitation in the Lisbon area, in the period 2010–2012, and in a continuous annual cycle of 2012 observations. Such behaviour is found to correlate positively with the probability of precipitation, especially in cases of severe rainfall. The evolution of the GPS PWV in a few stations is analysed by a least-squares fitting of a broken line tendency, made by a temporal sequence of ascents and descents over the data. It is found that most severe rainfall event occurs in descending trends after a long ascending period, and that the most intense events occur after steep ascents in PWV. A simple algorithm, forecasting rain in the 6 h after a steep ascent of the GPS PWV in a single station is found to produce reasonable forecasts of the occurrence of precipitation in the nearby region, without significant misses in what concerns larger rain events, but with a substantial amount of false alarms. It is suggested that this method could be improved by the analysis of 2-D or 3-D time varying GPS PWV fields, or by its joint use with other meteorological data relevant to nowcast precipitation.

Description: TITAN2F: a pseudo-3-D model of 2-phase debris flows Natural Hazards and Earth System Sciences Discussions, 3, 3789-3822, 2015 Author(s): G. Córdoba, M. F. Sheridan, and E. B. Pitman Debris flows, avalanches, landslides, and other geophysical mass flows can contain O (10 6 –10 10 ) m 3 or more of material. These flows commonly consist of mixture of soil and rocks with a significant quantity of interstitial fluid. They can be tens of meters deep, and their runouts can extend many kilometers. The complicated rheology of such a mixture challenges every constitutive model that can reasonably be applied; the range of length and timescales involved in such mass flows challenges the computational capabilities of existing systems.This paper extends recent efforts to develop a depth averaged "thin layer" model for geophysical mass flows that contain a mixture of solid material and fluid. Concepts from the engineering community are integrated with phenomenological findings in geo-science, resulting in a theory that accounts for the principal solid and fluid forces as well as interactions between the phases, across a wide range of solid volume fraction. A principal contribution here is to present drag and phase interaction terms that comport with the literature in geo-sciences. The program predicts the evolution of the concentration and dynamic pressure. The theory is validated with with data from one dimensional dam break solutions and it is verified with data from artificial channel experiments.

Description: Point release wet snow avalanches Natural Hazards and Earth System Sciences Discussions, 3, 2883-2912, 2015 Author(s): C. Vera Valero, Y. Bühler, and P. Bartelt Wet snow avalanches can initiate from large fracture slabs or small point releases. Point release wet snow avalanches can reach dangerous proportions when they (1) initiate on steep and long avalanche paths and (2) entrain warm moist snow. In this paper we investigate the dynamics of point release wet snow avalanches by applying a numerical model to simulate documented case studies on high altitude slopes in the Chilean Andes (33° S). The model predicts avalanche flow temperature as well as meltwater production, given the thermal initial conditions of the release mass and snowcover entrainment. As the release mass is small, avalanche velocity and runout are primarily controlled by snowcover temperature and moisture content. We demonstrate how the interaction between terrain and entrainment processes influence the production of meltwater and therefore lubrication processes leading to longer runout. This information is useful to avalanche forecasters. An understanding of wet snow avalanche dynamics is important to study how climate change scenarios will influence land usage in mountain regions in the near future.

Description: Appraising the Early-est earthquake monitoring system for tsunami alerting at the Italian candidate Tsunami Service Provider Natural Hazards and Earth System Sciences Discussions, 3, 2913-2952, 2015 Author(s): F. Bernardi, A. Lomax, A. Michelini, V. Lauciani, A. Piatanesi, and S. Lorito In this paper we present the procedure for earthquake location and characterization implemented in the Italian candidate Tsunami Service Provider at INGV in Roma. Following the ICG/NEAMTWS guidelines, the first tsunami warning messages are based only on seismic information, i.e. epicenter location, hypocenter depth and magnitude, which are automatically computed by the software Early-est. Early-est is a package for rapid location and seismic/tsunamigenic characterization of earthquakes. The Early-est software package operates on offline-event or continuous-realtime seismic waveform data to perform trace processing and picking, and, at a regular report interval , phase association, event detection, hypocenter location, and event characterization. In this paper we present the earthquake parameters computed by Early-est from the beginning of 2012 till the end of December 2014 at global scale for events with magnitude M ≥ 5.5, and the detection timeline. The earthquake parameters computed automatically by Early-est are compared with reference manually revised/verified catalogs. From our analysis the epicenter location and hypocenter depth parameters do not differ significantly from the values in the reference catalogs. The epicenter coordinates generally differ less than 20 ∓ 20 km from the reference epicenter coordinates; focal depths are less well constrained and differ generally less than 0 ∓ 30 km. Early-est also provides mb, M wp and M wpd magnitude estimations. mb magnitudes are preferred for events with M wp ≲ 5.8, while M wpd are valid for events with M wp ≳ 7.2. The magnitude mb show wide differences with respect to the reference catalogs, we thus apply a linear correction mb corr = mb · 0.52 + 2.46, such correction results into δmb ≈ 0.0 ∓ 0.2 uncertainty with respect the reference catalogs. As expected the M wp show distance dependency. M wp values at stations with epicentral distance Δ ≲ 30° are significantly overestimated with respect the CMT-global solutions, whereas M wp values at stations with epicentral distance Δ ≳ 90° are slightly underestimated. We thus apply a 3rd degree polynomial distance correction. After applying the distance correction, the M wp provided by Early-est differs from CMT-global catalog values of about δ M wp ≈ 0.0 ∓ 0.2. Early-est continuously acquires time series data and updates the earthquake source parameters. Our analysis shows that the epicenter coordinates and the magnitude values converge rather quickly toward the final values. Generally we can provide robust and reliable earthquake source parameters to compile tsunami warning message within less than about 15 min after event origin time.

Description: Storms or cold fronts? What is really responsible for the extreme waves regime in the Colombian Caribbean coast Natural Hazards and Earth System Sciences Discussions, 3, 3023-3055, 2015 Author(s): L. J. Otero, J. C. Ortiz-Royero, J. K. Ruiz-Merchan, A. E. Higgins, and S. A. Henriquez On Friday, 7 March 2009, a 200 m-long section of the tourist pier in Puerto Colombia collapsed under the impact of the waves generated by a cold front in the area. The aim of this study is to determine the contribution and importance of cold fronts and storms on extreme waves in different areas of the Colombian Caribbean to determine the degree of the threat posed by the flood processes to which these coastal populations are exposed and the actions to which coastal engineering constructions should be subject. In the calculation of maritime constructions, the most important parameter is the wave's height; therefore, it is necessary to definitively know the design wave height to which a coastal engineering structure should be resistant. This wave height varies according to the return period considered. Using Gumbel's extreme value methodology, the significant height values for the study area were calculated. The methodology was evaluated using data from the re-analysis of the spectral NOAA Wavewatch III (WW3) model for 15 points along the 1600 km of the Colombia Caribbean coast (continental and insular) of the last 15 years. The results demonstrated that the extreme waves caused by tropical cyclones and cold fronts have different effects along the Colombian Caribbean coast. Storms and hurricanes are of greater importance in the Guajira Peninsula (Alta Guajira). In the central area formed by Baja Guajira, Santa Marta, Barranquilla, and Cartagena, the strong influence of cold fronts on extreme waves is evident. On the other hand, in the southern region of the Colombian Caribbean coast, from the Gulf of Morrosquillo to the Gulf of Urabá, even though extreme waves are lower than in the previous regions, extreme waves are dominated mainly by the passage of cold fronts. Extreme waves in the San Andrés and Providencia insular region present a different dynamic from that in the continental area due to its geographic location. The wave heights in the extreme regime are similar in magnitude to those found in Alta Guajira, but the extreme waves associated with the passage of cold fronts in this region have lower return periods than the extreme waves associated with hurricane season. These results are of great importance when evaluating the threat of extreme waves in the coastal and port infrastructure, for purposes of the design of new constructions, and in the coastal flood processes due to run-up because, according to the site of interest in the coast, the forces that shape extreme waves are not the same.

Description: Early heat waves over Italy and their impacts on durum wheat yields Natural Hazards and Earth System Sciences Discussions, 3, 2953-2973, 2015 Author(s): G. Fontana, A. Toreti, A. Ceglar, and G. De Sanctis In the last decades the Euro-Mediterranean region has experienced an increase in extreme temperature events such as heat waves. These extreme weather conditions can strongly affect arable crop growth and final yields. Here, early heat waves over Italy from 1995 to 2013 are identified and characterised and their impact on durum wheat yields is investigated. As expected, results confirm the impact of the 2003 heat waves and highlight a high percentage of concurrence of early heat waves and significant negative yield anomalies in 13 out of 39 durum wheat production areas. In south-eastern Italy (the most important area for durum wheat production), the percentage of concurrent events exceeds 80%.

Description: Soil geohazard mapping for improved asset management of UK local roads Natural Hazards and Earth System Sciences Discussions, 3, 3151-3180, 2015 Author(s): O. G. Pritchard, S. H. Hallett, and T. S. Farewell Unclassified roads comprise 60% of the road network in the United Kingdom (UK). The resilience of this locally important network is declining. It is considered by the Institution of Civil Engineers to be "at risk" and is ranked 26th in the world. Many factors contribute to the degradation and ultimate failure of particular road sections. However, several UK local authorities have identified that in drought conditions, road sections founded upon shrink/swell susceptible clay soils undergo significant deterioration compared with sections on non-susceptible soils. This arises from the local road network having little, if any structural foundations. Consequently, droughts in East Anglia have resulted in millions of pounds of damage, leading authorities to seek emergency governmental funding. This paper assesses the use of soil-related geohazard assessments in providing soil-informed maintenance strategies for the asset management of the locally important road network of the UK. A case study draws upon the UK administrative county of Lincolnshire, where road assessment data have been analysed against mapped clay-subsidence risk. This reveals a statistically significant relationship between road condition and susceptible clay soils. Furthermore, incorporation of UKCP09 future climate projections within the geohazard models has highlighted roads likely to be at future risk of clay-related subsidence.

Description: Role of intertidal wetlands for tidal and storm tide attenuation along a confined estuary: a model study Natural Hazards and Earth System Sciences Discussions, 3, 3181-3224, 2015 Author(s): S. Smolders, Y. Plancke, S. Ides, P. Meire, and S. Temmerman Coastal lowlands and estuaries are subjected to increasing flood risks during storm surges due to global and regional changes. Tidal wetlands are increasingly valued as effective natural buffers for storm surges by dissipating wave energy and providing flood water storage. While previous studies focused on flood wave attenuation within and behind wetlands, this study focuses on the effects of estuarine wetland properties on the attenuation of a storm tide that propagates along the length of an estuary. Wetland properties including elevation, surface area, and location within the estuary were investigated using a numerical model of the Scheldt estuary (Belgium, SW Netherlands). For a spring tide lower wetland elevations result in more attenuation of high water levels along the estuary, while for a higher storm tide higher elevations provide more attenuation compared to lower wetland elevations. For spring and storm tide a arger wetland surface area results in a better attenuation along the estuary up to a threshold wetland size for which larger wetlands do not further contribute to more attenuation. Finally a wetland of the same size and elevation, but located more upstream in the estuary, can store a larger proportion of the local flood volume and therefore has a larger attenuating effect on upstream high water levels. With this paper we aim to contribute towards a better understanding and wider implementation of ecosystem-based adaptation to increasing estuarine flood risks associated with storms.

Description: Flash flood occurrence and relation to the rainfall hazard in a highly urbanized area Natural Hazards and Earth System Sciences Discussions, 3, 3119-3149, 2015 Author(s): K. Papagiannaki, K. Lagouvardos, V. Kotroni, and A. Bezes The paper examines the flash flood events that occurred during a decade in the Attica prefecture, the most urbanized region of Greece, with the aim of assessing the local vulnerability to the flash flood hazard and the effect of rainfall upon the magnitude of the induced damages. The analysis incorporates rainfall records from a network of 28 surface meteorological stations and information on the spatial distribution of the flash flood events that is derived from the active database of damaging weather events maintained by the atmospheric modelling group of the National Observatory of Athens. The main findings concern the relation between the flash flood impact, as measured by the Fire Service operations in flooded properties, and precipitation in various time intervals, as well as the possibility to define rainfall intensity thresholds for flood triggering at a more local level. It is shown that the quality of the produced thresholds depends on the distribution and density of the rain gauges that cover each specified geographical area of the Attica region.

Description: Spatial analysis of damaged vegetation in the Mianyuan River basin after the Wenchuan Earthquake Natural Hazards and Earth System Sciences Discussions, 3, 3225-3250, 2015 Author(s): H. Z. Zhang, J. R. Fan, X. M. Wang, T. H. Chi, and L. Peng The 2008 Wenchuan earthquake destroyed large areas of vegetation. Presently, these areas of damaged vegetation are at various stages of recovery. In this study, we present a probabilistic approach for slope stability analysis that quantitatively relates data on earthquake-damaged vegetation with slope stability in a given river basin. The Mianyuan River basin was selected for model development, and earthquake-damaged vegetation and post-earthquake recovery conditions were identified via the normalized difference vegetation index (NDVI), from multi-temporal (2001–2014) remote sensing images. DSAL (digital elevation model, slope, aspect, and lithology) spatial zonation was applied to characterize the survival environments of vegetation, which were used to discern the relationships between successful vegetation regrowth and environmental conditions. Finally, the slope stability susceptibility model was trained through multivariate analysis of earthquake-damaged vegetation and its controlling factors (i.e. topographic environments and material properties). Application to the Subao River basin validated the proposed model, showing that most of the damaged vegetation areas have high susceptibility levels (88.1% 〉 susceptibility level 3, and 61.5% 〉 level 4). Our modelling approach may also be valuable for use in other regions prone to landslide hazards.

Description: Variations in water storage in China over recent decade from GRACE Observations and GLDAS Natural Hazards and Earth System Sciences Discussions, 3, 3251-3286, 2015 Author(s): X. Mo, J. Wu, Q. Wang, and H. Zhou We applied GRACE Tellus products in combination with GLDAS simulations and data from reports, to analyze variations in terrestrial water storage (TWS) in China and eight of its basins from 2003 to 2013. Amplitudes of TWS were well restored after scaling, and showed good correlations with those estimated from models at the basin scale. TWS generally followed variations in annual precipitation, it decreased linearly in Huai River basin (−0.564 cm yr −1 ) and increased with fluctuations in Changjiang River basin (0.348 cm yr −1 ), Zhujiang basin (0.552 cm yr −1 ) and Southeast Rivers basin (0.696 cm yr −1 ). In Hai River basin and Yellow River basin, groundwater exploitation may have altered TWS's response to climate, but it began to restore since 2012. Changes in soil moisture storage contributed over 50% in of variances in TWS in most basins. Precipitation and runoff showed large impact on TWS, with explained variances higher in TWS in the south than in the north. North China and Southwest Rivers region exhibited long-term TWS depletions. TWS increased significantly over the recent decade in the middle and lower reaches of Changjiang, southeastern coastal area, as well as the Hoh Xil, and headstream region of the Yellow River in Tibetan plateau. The findings in this study could be helpful to climate change impact research and disaster mitigation planning.

Description: Evaluation of shallow landslide triggering scenarios through a physically-based approach: an example of application in the southern Messina area (north-eastern Sicily, Italy) Natural Hazards and Earth System Sciences Discussions, 3, 2975-3022, 2015 Author(s): L. Schilirò, C. Esposito, and G. Scarascia Mugnozza Rainfall-induced shallow landslides are a widespread phenomenon that frequently causes substantial damage to property, as well as numerous casualties. In recent years a wide range of physically-based models has been developed to analyze the triggering process of these events. Specifically, in this paper we propose an approach for the evaluation of different shallow landslide triggering scenarios by means of TRIGRS numerical model. For the calibration of the model, a back-analysis of the landslide event occurred in the study area (located SW of Messina, north-eastern Sicily, Italy) on 1 October 2009 was performed, by using different methods and techniques for the definition of the input parameters. After evaluating the reliability of the model through the comparison with the 2009 landslide inventory, different triggering scenarios were defined using rainfall values derived from the rainfall probability curves, reconstructed on the basis of daily and hourly historical rainfall data. The results emphasize how these phenomena are likely to occur in the area, given that even short-duration (3–6 h) rainfall events having a relatively low return period (e.g. 10 years) can trigger numerous slope failures. On the contrary, for the same rainfall amount, the daily simulations overestimate the instability conditions. The tendency of shallow landslides to trigger in this area agrees with the high number of landslide/flood events occurred in the past and summarized in this paper by means of archival researches. Considering the main features of the proposed approach, the authors suggest that this methodology could be applied to different areas, even for the development of landslide early warning systems.

Description: Hydroelastic analysis of ice shelves under long wave excitation Natural Hazards and Earth System Sciences Discussions, 3, 3057-3075, 2015 Author(s): T. K. Papathanasiou, A. E. Karperaki, E. E. Theotokoglou, and K. A. Belibassakis The transient hydroelastic response of an ice shelf under long wave excitation is analysed by means of the finite element method. The simple model, presented in this work, is used for the simulation of the generated kinematic and stress fields in an ice shelf, when the latter interacts with a tsunami wave. The ice shelf, being of large length compared to its thickness, is modelled as an elastic Euler–Bernoulli beam, constrained at the grounding line. The hydrodynamic field is represented by the linearised shallow water equations. The numerical solution is based on the development of a special hydroelastic finite element for the system of governing of equations. Motivated by the 2011 Sulzberger Ice Shelf (SIS) calving event and its correlation with the Honshu Tsunami, the SIS stable configuration is studied. The extreme values of the bending moment distribution in both space and time are examined. Finally, the location of these extrema is investigated for different values of ice shelf thickness and tsunami wave length.

Description: Runup parameterization and beach vulnerability assessment on a barrier island: a downscaling approach Natural Hazards and Earth System Sciences Discussions, 3, 3077-3117, 2015 Author(s): G. Medellín, J. A. Brinkkemper, A. Torres-Freyermuth, C. M. Appendini, E. T. Mendoza, and P. Salles We present a downscaling approach for the study of wave-induced extreme water levels at a location on a barrier island in Yucatan (Mexico). Wave information from a 30 year wave hindcast is validated with in situ measurements at 8 m water depth. The Maximum Dissimilarity Algorithm is employed for the selection of 600 representative cases, encompassing different wave characteristics and tidal level combinations. The selected cases are propagated from 8 m water depth till the shore using the coupling of a third-generation wave model and a phase-resolving non-hydrostatic Nonlinear Shallow Water Equations model. Extreme wave runup, R 2% , is estimated for the simulated cases and can be further employed to reconstruct the 30 year period using an interpolation algorithm. Downscaling results show runup saturation during more energetic wave conditions and modulation owing to tides. The latter suggests that the R 2% can be parameterized using a hyperbolic-like formulation with dependency on both wave height and tidal level. The new parametric formulation is in agreement with the downscaling results ( r 2 = 0.78), allowing a fast calculation of wave-induced extreme water levels at this location. Finally, an assessment of beach vulnerability to wave-induced extreme water level is conducted at the study area by employing the two approaches (reconstruction/parametrization) and a storm impact scale. The 30 year extreme water level hindcast allows the calculation of beach vulnerability as a function of return periods. It is shown that the downscaling-derived parameterization provides reasonable results as compared with the numerical approach. This methodology can be extended to other locations and can be further improved by incorporating the storm surge contributions to the extreme water level.

Description: Regional trends and controlling factors of fatal landslides in Latin America and the Caribbean Natural Hazards and Earth System Sciences Discussions, 3, 2777-2809, 2015 Author(s): S. A. Sepúlveda and D. N. Petley A database of landslides that caused loss of life in Latin America and the Caribbean in the period from 2004 and 2013 inclusive has been compiled using established techniques. This database indicates that in the ten year period a total of 11 631 people lost their lives across the region in 611 landslides. The geographical distribution of the landslides is very heterogeneous, with areas of high incidence in parts of the Caribbean (most notably Haiti), Central America, Colombia, and SE. Brazil. The number of landslides varies considerably between years; the El Niño/La Niña cycle emerges as a major factor controlling this variation, although the study period did not capture a large event. Analysis suggests that on a continental scale the mapped factors that best explain the observed distribution are topography, annual precipitation and population density. On a national basis we have compared the occurrence of fatality-inducing landslide occurrence with the production of research articles with a local author, which shows that there is a landslide research deficit in Latin America and the Caribbean. Understanding better the mechanisms, distributions causes and triggers of landslides in Latin America and the Caribbean must be an essential first step towards managing the hazard.

Description: Estimation of insurance related losses resulting from coastal flooding in France Natural Hazards and Earth System Sciences Discussions, 3, 2811-2846, 2015 Author(s): J. P. Naulin, D. Moncoulon, S. Le Roy, R. Pedreros, D. Idier, and C. Oliveros A model has been developed in order to estimate insurance-related losses caused by coastal flooding in France. The deterministic part of the model aims at identifying the potentially flood-impacted sectors and the subsequent insured losses a few days after the occurrence of a storm surge event on any part of the French coast. This deterministic component is a combination of three models: a hazard model, a vulnerability model and a damage model. The first model uses the PREVIMER system to estimate the water level along the coast. A storage-cell flood model propagates these water levels over the land and thus determines the probable inundated areas. The vulnerability model, for its part, is derived from the insurance schedules and claims database; combining information such as risk type, class of business and insured values. The outcome of the vulnerability and hazard models are then combined with the damage model to estimate the event damage and potential insured losses. This system shows satisfactory results in the estimation of the magnitude of the known losses related to the flood caused by the Xynthia storm. However, it also appears very sensitive to the water height estimated during the flood period, conditioned by the junction between sea water levels and coastal topography for which the accuracy is still limited in the system.

Description: Laboratory tests for the optimization of mesh size for flexible debris-flow barriers Natural Hazards and Earth System Sciences Discussions, 3, 2099-2118, 2015 Author(s): C. Wendeler and A. Volkwein Laboratory tests were performed to study the loading aspects of flexible debris-flow barriers. Debris material from the Milibach river (Canton Berne, Switzerland) has been used to quantify the influence of different mesh sizes and the gap between the lower barrier edge and the river bed compared to the maximum grain size. It was possible to study the filling process and the retaining behaviour of the barriers as a function of the mesh size. A reasonable retention was reached with the net having a mesh size and a basal gap smaller than d 90 where d 90 is the maximum diameter of 90% of the grains. By scaling the laboratory tests to the natural size using Froude similarity a recommendation is given for the best net mesh size and the gap in natural conditions. The conclusions are supported by the results of numerous laboratory tests using different debris material, e.g. from the Illgraben river (Canton Valais).

Description: An assessment of the potential of earth observation data to detect and monitor storm cells associated with natural hazards – an application to an extreme weather event in southeastern Mediterranean Natural Hazards and Earth System Sciences Discussions, 3, 2191-2219, 2015 Author(s): T. Mavrakou and C. Cartalis Storm cells that evolve in Mesoscale Convective Systems (MCSs) can be recognised with the use of satellite images. In this study, Meteosat images are used for the early detection and monitoring of the evolution of storm cells associated with MCSs. The developed methodology is based on the estimation of the "Airmass" and "Convective storm" composites, at fifteen minutes intervals. The methodology was applied on a selected four-day case study in February 2013, when a depression was developed over Africa and moved across the Mediterranean resulting in deep convection along its trajectory and in an extreme weather event (heavy rainfall associated with severe flooding) at the wider urban agglomeration of Athens. The produced composites detect potential vorticity (PV) anomaly related to cyclogenesis and increase the potential to detect and monitor storm cells associated with natural hazards.

Description: The asymmetric impact of natural disasters on China's bilateral trade Natural Hazards and Earth System Sciences Discussions, 3, 2003-2023, 2015 Author(s): Y. Meng, P. Shi, S. Yang, and C. C. Jeager Globalization and technological revolutions are making the world more interconnected. International trade is one of the major approaches linking the world. Since the 2011 Tohoku earthquake and tsunami in Japan shocked the global supply chain, more attention has been paid to the global impact of large-scale disasters. China is the second largest trader in the world and faces the most frequent natural disasters. Therefore, this study proposes a gravity model for China's bilateral trade tailored to national circumstances, and estimates the impact of natural disasters in China and trading partner countries on Chinese imports and exports. We analyzed Chinese and trading partner statistical data from 1980 to 2012. Study results show that: (1) China's natural disasters have a positive impact on imports, but have no significant impact on exports, (2) trading partner countries' natural disasters reduce Chinese imports and exports, (3) both development level and land area of the partners are important in determining the intensity of natural disaster impacts on China's bilateral trade. The above findings suggest that the impact of natural disasters on trade is asymmetric and significantly affected by other factors, which demand further study.

Description: New estimates of potential impacts of sea level rise and coastal floods in Poland Natural Hazards and Earth System Sciences Discussions, 3, 2493-2536, 2015 Author(s): D. Paprotny and P. Terefenko Polish coastal zone is thought to be of the most exposed to sea level rise in Europe. With climate change expected to raise mean sea levels between 26 and 200 cm by the end of the century, and storms increasing in severity, accurate estimates of those phenomena are needed. Recent advances in quality and availability of spatial data in Poland made in possible to revisit previous estimates. Up-to-date detailed information on land use, population and buildings were used to calculate inundation risk at a broad range of scenarios. Inclusion, though imperfect, of flood defences from a high-resolution digital elevation model contributes to a further improvement of estimates. The results revealed that even by using a static "bathtub fill" approach the amount of land, population or assets at risk has been significantly revised down. Sea level rise or storm surges are unlikely to reach intensity required to cause significant damage to the economy or endanger the population. The exposure of different kinds of assets and sectors of the economy varies to a large extent, though the structural breakdown of potential losses is remarkably stable between scenarios.

Description: Debris flow susceptibility mapping using a qualitative heuristic method and Flow-R along the Yukon Alaska Highway Corridor, Canada Natural Hazards and Earth System Sciences Discussions, 3, 3509-3541, 2015 Author(s): A. Blais-Stevens and P. Behnia This research activity aimed at reducing risk to infrastructure, such as a proposed pipeline route roughly parallel to the Yukon Alaska Highway Corridor (YAHC) by filling geoscience knowledge gaps in geohazards. Hence, the Geological Survey of Canada compiled an inventory of landslides including debris flow deposits, which were subsequently used to validate two different debris flow susceptibility models. A qualitative heuristic debris flow susceptibility model was produced for the northern region of the YAHC, from Kluane Lake to the Alaska border, by integrating data layers with assigned weights and class ratings. These were slope angle, slope aspect (derived from a 5 m × 5 m DEM), surficial geology, permafrost distribution, and proximity to drainage system. Validation of the model was carried out by calculating a success rate curve which revealed a good correlation with the susceptibility model and the debris flow deposit inventory compiled from air photos, high resolution satellite imagery, and field verification. In addition, the quantitative Flow-R method was tested in order to define the potential source and debris flow susceptibility for the southern region of Kluane Lake, an area where documented debris flow events have blocked the highway in the past (e.g., 1988). Trial and error calculations were required for this method because there was not detailed information on the debris flows for the YAHC to allow us to define threshold values for some parameters when calculating source areas, spreading, and runout distance. Nevertheless, correlation with known documented events helped define these parameters and produce a map that captures most of the known events and displays debris flow susceptibility in other, usually smaller, steep channels that had not been previously documented.

Description: Representative rainfall thresholds for flash floods in the Cali river watershed, Colombia Natural Hazards and Earth System Sciences Discussions, 3, 4095-4119, 2015 Author(s): A. D. Ávila, Y. E. Carvajal, and F. Justino In the 21st century, societies face a significant increase in the number of extreme hydrometeorological events associated with climate variability (CV) and/or climate change (CC). Research has recently focused on establishing adaptation and mitigation measures to counteract the effects of CV and CC, especially those associated with precipitation, such as flash floods and flooding. In this study, 27 floods, listed in the historical database of natural disasters (DesInventar), occurring between 1980 and 2012, were analyzed. Using the daily hydrometeorological data, representative rainfall thresholds were defined to predict flash floods in the hydrographic basin of the Cali River, Colombia. Antecedent rainfall (AR), or short-term rain (1, 3, 5 and 7 days), and accumulated antecedent rainfall (AAR), or long-term rain (5, 7, 10, 15, 20, 25, 30, 60 and 90 days), levels were defined. The analysis showed that the greatest determinant for the occurrence of floods is AAR, with thresholds greater than 73, 95, 124, 170, 218 and 273 mm, for 5, 7, 10, 15, 20 and 25 days, respectively. Additionally, the data showed that, historically, the greatest number of flash floods (81.7 %) occurred in the Cali River basin in the months of April, May, and June.

Description: 3-D-numerical approach to simulate an avalanche impact into a reservoir Natural Hazards and Earth System Sciences Discussions, 3, 4121-4157, 2015 Author(s): R. Gabl, J. Seibl, B. Gems, and M. Aufleger The impact of an avalanche into a reservoir induces an impulse wave, which poses a threat to population and infrastructure. For a good approximation of the generated wave height and length as well as the resulting outflow volume over structures and dams, formulas, which base on different simplifying assumptions, can be used. Further project-specific investigations by means of a scale model test or numerical simulations are advisable for complex reservoirs as well as the inclusion of hydraulic structures such as spillways. The paper presents a new approach for a 3-D-numerical simulation of an avalanche impact into a reservoir. In this model concept the energy and mass of the avalanche are represented by accelerated water on the real hill slope. Instead of snow, only water and air are used to simulate the moving avalanche with the software FLOW-3D. A significant advantage of this assumption is the self-adaptation of the model avalanche onto the terrain. In order to reach good comparability of the results with existing research at the ETH Zürich, a simplified reservoir geometry is investigated. Thus, a reference case has been analysed including a variation of three geometry parameters (still water depth in the reservoir, freeboard of the dam and reservoir width).

Description: Behavior analysis by model slope experiment of artificial rainfall Natural Hazards and Earth System Sciences Discussions, 3, 4159-4187, 2015 Author(s): M. C. Park In this study, we performed a model slope experiment with rainfall seepage, and the results were compared and verified with the unsaturated slope stability analysis method. In the model slope experiment, we measured the changes in water content and matric suction due to rainfall seepage, and determined the time at which the slope failure occurred and the shape of the failure. In addition, we compared and verified the changes in the factor of safety and the shape of the failure surface, which was calculated from the unsaturated slope stability analysis with the model experiment. From the results of experiment and analysis, it is concluded that the unsaturated slope stability analysis can be used to accurately analyze and predict rainfall-induced slope failure. It is also concluded that in seepage analysis, setting the initial conditions and boundary conditions is very important. If engineers will use the measured pore water pressure or matric suction, the accuracy of analysis can be enhanced. The real-time monitoring system of pore water pressure or matric suction can be used as a warning of rainfall-induced slope failure.

Description: An interactive web-GIS tool for risk analysis: a case study in the Fella River Basin, Italy Natural Hazards and Earth System Sciences Discussions, 3, 4007-4057, 2015 Author(s): Z. C. Aye, M. Jaboyedoff, M. H. Derron, C. J. van Westen, H. Y. Hussin, R. L. Ciurean, S. Frigerio, and A. Pasuto This paper presents a prototype of an interactive web-GIS tool for risk analysis of natural hazards, in particular for floods and landslides, based on open-source geospatial software and technologies. The aim of the presented tool is to assist the experts (risk managers) in analysing the impacts and consequences of a certain hazard event in a considered region, providing an essential input to the decision making process in the selection of risk management strategies by responsible authorities and decision makers. This tool is based on the Boundless (OpenGeo Suite) framework and its client side environment for prototype development, and it is one of the main modules of a web-based collaborative decision support platform in risk management. Within this platform, the users can import necessary maps and information to analyse areas at risk. Based on provided information and parameters, loss scenarios (amount of damages and number of fatalities) of a hazard event are generated on-the-fly and visualized interactively within the web-GIS interface of the platform. The annualized risk is calculated based on the combination of resultant loss scenarios with different return periods of the hazard event. The application of this developed prototype is demonstrated using a regional data set from one of the case study sites, Fella River of North Eastern Italy, of the Marie Curie ITN CHANGES project.

Description: Climate change adaptation frameworks: an evaluation of plans for coastal, Suffolk, UK Natural Hazards and Earth System Sciences Discussions, 3, 4059-4094, 2015 Author(s): J. Armstrong, R. Wilby, and R. J. Nicholls This paper asserts that three principal frameworks for climate change adaptation can be recognised in the literature: Scenario-Led (SL), Vulnerability-Led (VL) and Decision–Centric (DC) frameworks. A criterion is developed to differentiate these frameworks in recent adaptation projects. The criterion features six key hallmarks as follows: (1) use of climate model information; (2) analysis metrics/units; (3) socio-economic knowledge; (4) stakeholder engagement; (5) adaptation implementation mechanisms; (6) tier of adaptation implementation. The paper then tests the validity of this approach using adaptation projects on the Suffolk coast, UK. Fourteen adaptation plans were identified in an online survey. They were analysed in relation to the hallmarks outlined above and assigned to an adaptation framework. The results show that while some adaptation plans are primarily SL, VL or DC, the majority are hybrid showing a mixture of DC/VL and DC/SL characteristics. Interestingly, the SL/VL combination is not observed, perhaps because the DC framework is intermediate and attempts to overcome weaknesses of both SL and VL approaches. The majority (57 %) of adaptation projects generated a risk assessment or advice notes. Further development of this type of framework analysis would allow better guidance on approaches for organisations when implementing climate change adaptation initiatives, and other similar proactive long-term planning.

Description: Evaluation of social vulnerability to floods in Huaihe River basin: a methodology based on catastrophe theory Natural Hazards and Earth System Sciences Discussions, 3, 4937-4965, 2015 Author(s): W. J. You and Y. L. Zhang Huaihe River is one of the seven largest rivers in China, in which floods occurred frequently. Disasters cause huge casualties and property losses to the basin, and also make it famous for high social vulnerability to floods. Based on the latest social-economic data, the index system of social vulnerability to floods was constructed, and Catastrophe theory method was used in the assessment process. The conclusion shows that social vulnerability as a basic attribute attached to urban environment, with significant changes from city to city across the Huaihe River basin. Different distribution characteristics are present in population, economy, flood prevention vulnerability. It is important to make further development of social vulnerability, which will play a positive role in disaster prevention, improvement of comprehensive ability to respond to disasters.

Description: Using open building data in the development of exposure datasets for catastrophe risk modelling Natural Hazards and Earth System Sciences Discussions, 3, 5045-5084, 2015 Author(s): R. Figueiredo and M. Martina One of the necessary components to perform catastrophe risk modelling is information on the buildings at risk, such as their spatial location, geometry, height, occupancy type and other characteristics. This is commonly referred to as the exposure model or dataset. When modelling large areas, developing exposure datasets with the relevant information about every individual building is not practicable. Thus, census data at coarse spatial resolutions are often used as the starting point for the creation of such datasets, after which disaggregation to finer resolutions is carried out using different methods, based on proxies such as the population distribution. While these methods can produce acceptable results, they cannot be considered ideal. Nowadays, the availability of open data is increasing and it is possible to obtain information about buildings for some regions. Although this type of information is usually limited and, therefore, insufficient to generate an exposure dataset, it can still be very useful in its elaboration. In this paper, we focus on how open building data can be used to develop a gridded exposure model by disaggregating existing census data at coarser resolutions. Furthermore, we analyse how the selection of the level of spatial resolution can impact the accuracy and precision of the model, and compare the results in terms of affected residential building areas, due to a flood event, between different models.

Description: Spatial impact and triggering conditions of the exceptional hydro-geomorphological event of December 1909 in Iberia Natural Hazards and Earth System Sciences Discussions, 3, 5805-5845, 2015 Author(s): S. Pereira, A. M. Ramos, J. L. Zêzere, R. M. Trigo, and J. M. Vaquero According to the DISASTER database the 20–28 December 1909 was the hydro-geomorphologic event with the highest number of flood and landslide cases occurred in Portugal in the period 1865–2010 (Zêzere et al., 2014). This event also caused important social impacts over the Spanish territory, especially in the Douro basin, having triggered the highest floods in more than 100 years at the river's mouth in the city of Oporto. This work aims to characterize the spatial distribution and social impacts of the December 1909 hydro-geomorphologic event over Iberia. In addition, the meteorological conditions that triggered the event are analysed using the 20 Century Reanalysis dataset from NOAA and precipitation data from Iberian meteorological stations. The Iberian Peninsula was spatially affected during this event along the SW-NE direction spanning from Lisbon, Santarém, Oporto and Guarda (in Portugal), until Salamanca, Valladolid, Zamora, Orense, León and Palencia (in Spain). In Iberia, 134 DISASTER cases were recorded (130 flood cases; 4 landslides cases) having caused a total of 89 casualties (57 in floods and 32 in landslides) and a total of 3876 people were affected, including fatalities, injured, missing, evacuated and homeless people. This event was associated with some outstanding precipitation values at Guarda station (Portugal) in 22 December 1909 and unusual meteorological conditions characterized by the presence of a deep low pressure system located over NW Iberian Peninsula with a stationary frontal system striking the Western Iberian Peninsula. The presence of an upper-level jet (250 hPa) and low-level jet (900 hPa) located on SW-NE oriented towards the Iberia along with upper-level divergence and lower-level convergence favoured large-scale precipitation. Finally, associated with these features it is possible to state that this extreme event was clearly associated to the presence of an elongated Atmospheric River, crossing the entire northern Atlantic basin and providing a continuous supply of moisture that contributed to enhance precipitation. This work contributes to a comprehensive and systematic synoptic evaluation of the second most deadly hydro-geomorphologic Disaster event occurred in Portugal since 1865 and will help to better understand the meteorological system that was responsible for triggering the event.

Description: Effectiveness and efficiency of slot-check dam system on debris flow control Natural Hazards and Earth System Sciences Discussions, 3, 5777-5804, 2015 Author(s): Y. H. Zou and X. Q. Chen Slot-check dam system is commonly used to control sediment transport associated with debris flows and mitigate debris flow hazards. This paper aims to estimate the performance of the slot-check dam system in the field and set up a verification to evaluate the efficiency of a slot-check dam system and each subsystem in debris flow sediment control. Field survey on a group of a series of slot-check dams at Shengou Basin in Yunnan, China reveals that the conserving sediment volume of each dam is related to its relative location in the group, gradually decreasing from upstream to downstream. The cumulative sediment volume within a subsystem of slot-check dams closely related to the characteristics of the catchment controlled by the subsystem. It increases with the controlled catchment area of the most downstream dam in subsystem and the distance from the dam to the upstream most. Evaluation models for the conserving efficiency of a slot-check dam system on debris flow control in a river basin and each subsystem within the group associate to the controlled catchment characteristics have been proposed. The layout principle of a slot-check dam system in a river basin has been developed based on the conserving efficiency of a subsystem of slot-check dams which would allow the slot-check dam system to be designed in a more scientific way.

Description: AEGIS: a wildfire prevention and management information system Natural Hazards and Earth System Sciences Discussions, 3, 6185-6228, 2015 Author(s): K. Kalabokidis, A. Ager, M. Finney, N. Athanasis, P. Palaiologou, and C. Vasilakos A Web-GIS wildfire prevention and management platform (AEGIS) was developed as an integrated and easy-to-use decision support tool ( http://aegis.aegean.gr ). The AEGIS platform assists with early fire warning, fire planning, fire control and coordination of firefighting forces by providing access to information that is essential for wildfire management. Databases were created with spatial and non-spatial data to support key system functionalities. Updated land use/land cover maps were produced by combining field inventory data with high resolution multispectral satellite images (RapidEye) to be used as inputs in fire propagation modeling with the Minimum Travel Time algorithm. End users provide a minimum number of inputs such as fire duration, ignition point and weather information to conduct a fire simulation. AEGIS offers three types of simulations; i.e. single-fire propagations, conditional burn probabilities and at the landscape-level, similar to the FlamMap fire behavior modeling software. Artificial neural networks (ANN) were utilized for wildfire ignition risk assessment based on various parameters, training methods, activation functions, pre-processing methods and network structures. The combination of ANNs and expected burned area maps produced an integrated output map for fire danger prediction. The system also incorporates weather measurements from remote automatic weather stations and weather forecast maps. The structure of the algorithms relies on parallel processing techniques (i.e. High Performance Computing and Cloud Computing) that ensure computational power and speed. All AEGIS functionalities are accessible to authorized end users through a web-based graphical user interface. An innovative mobile application, AEGIS App, acts as a complementary tool to the web-based version of the system.

Description: Regional prioritisation of flood risk in mountainous areas Natural Hazards and Earth System Sciences Discussions, 3, 4265-4314, 2015 Author(s): M. C. Rogelis, M. Werner, N. Obregón, and G. Wright A regional analysis of flood risk was carried out in the mountainous area surrounding the city of Bogotá (Colombia). Vulnerability at regional level was assessed on the basis of a principal component analysis carried out with variables recognised in literature to contribute to vulnerability; using watersheds as the unit of analysis. The area exposed was obtained from a simplified flood analysis at regional level to provide a mask where vulnerability variables were extracted. The vulnerability indicator obtained from the principal component analysis was combined with an existing susceptibility indicator, thus providing an index that allows the watersheds to be prioritised in support of flood risk management at regional level. Results show that the components of vulnerability can be expressed in terms of four constituent indicators; socio-economic fragility, which is composed of demography and lack of well-being; lack of resilience, which is composed of education, preparedness and response capacity, rescue capacity, social cohesion and participation; and physical exposure is composed of exposed infrastructure and exposed population. A sensitivity analysis shows that the classification of vulnerability is robust for watersheds with low and high values of the vulnerability indicator, while some watersheds with intermediate values of the indicator are sensitive to shifting between medium and high vulnerability. The complex interaction between vulnerability and hazard is evidenced in the case study. Environmental degradation in vulnerable watersheds shows the influence that vulnerability exerts on hazard and vice versa, thus establishing a cycle that builds up risk conditions.

Description: Patterns and trends of high-impact weathers in China during 1959–2014 Natural Hazards and Earth System Sciences Discussions, 3, 6149-6184, 2015 Author(s): J. Shi, K. Wen, and L. Cui The spatial and temporal characteristics in the frequencies of four types of high-impact weathers (HIWs), i.e. snowfall, thunderstorm, foggy and hailstorm weathers were analyzed in China by using daily weather phenomenon data from 604 stations. Results indicate that snowfall, thunderstorm, foggy and hailstorm days showed significant decreasing trends with rates of 2.5, 2.6, 0.8 and 0.5 days per decade respectively, and snowfall, thunderstorm, foggy and hailstorm weather processes decreased significantly at rates of 0.3, 0.4, 0.1 and 0.1 times per decade during 1959–2014. Spatially, snowfall weathers were more in northeastern and western China, and thunderstorm weathers were more in southern and southwestern China. Foggy weathers were more in some high mountain stations, eastern China and central China, and hailstorm weathers were concentrated on Qinghai–Tibet Plateau. Over the past 56 years, snowfall days, thunderstorm days and thunderstorm weather processes decreased in most parts of China, with decreasing rates of 1.0–6.0 days, 1.5–8.0 days and 0.2–1.0 times per decade respectively. Hailstorm days decreased in northeastern China and most parts of northern and western China at a rate of 0.2–4.5 days per decade. The spatial trends of foggy days, foggy weather processes and snowfall weather processes were not significant in most parts of China. With climate change and rapidly economic development, more policies and strategies of reducing social vulnerabilities and/or exposures to HIWs are essential for the government and social publics.

Description: The unrest of S. Miguel volcano (El Salvador, CA): installation of the monitoring network and observed volcano-tectonic ground deformation Natural Hazards and Earth System Sciences Discussions, 3, 6117-6148, 2015 Author(s): A. Bonforte, D. Hernandez, E. Gutiérrez, L. Handal, C. Polío, S. Rapisarda, and P. Scarlato On 29 December 2013, the Chaparrastique volcano in El Salvador, close to the town of S. Miguel, erupted suddenly with explosive force, forming a more than 9 km high column and projecting ballistic projectiles as far as 3 km away. Pyroclastic Density Currents flowed to the north-northwest side of the volcano, while tephras were dispersed northwest and north-northeast. This sudden eruption prompted the local Ministry of Environment to request cooperation with Italian scientists in order to improve the monitoring of the volcano during this unrest. A joint force made up of an Italian team from the Istituto Nazionale di Geofisica e Vulcanologia and a local team from the Ministerio de Medio Ambiente y Recursos Naturales was organized to enhance the volcanological, geophysical and geochemical monitoring system to study the evolution of the phenomenon during the crisis. The joint team quickly installed a multi-parametric mobile network comprising seismic, geodetic and geochemical sensors, designed to cover all the volcano flanks from the lowest to the highest possible altitudes, and a thermal camera. To simplify the logistics for a rapid installation and for security reasons, some sensors were co-located into multi-parametric stations. Here, we describe the prompt design and installation of the geodetic monitoring network, the processing and results. The installation of a new ground deformation network can be considered an important result by itself, while the detection of some crucial deforming areas is very significant information, useful for dealing with future threats and for further studies on this poorly monitored volcano.

Description: Quantifying the effect of sea level rise and flood defence – apoint process perspective on coastal flood damage Natural Hazards and Earth System Sciences Discussions, 3, 6229-6269, 2015 Author(s): M. Boettle, D. Rybski, and J. P. Kropp In contrast to recent advances in projecting sea levels, estimations about the economic impact of sea level rise are vague. Nonetheless, they are of great importance for policy making with regard to adaptation and greenhouse-gas mitigation. Since the damage is mainly caused by extreme events, we propose a stochastic framework to estimate the monetary losses from coastal floods in a confined region. For this purpose, we follow a Peak-over-Threshold approach employing a Poisson point process and the Generalised Pareto Distribution. By considering the effect of sea level rise as well as potential adaptation scenarios on the involved parameters, we are able to study the development of the annual damage. An application to the city of Copenhagen shows that a doubling of losses can be expected from a mean sea level increase of only 11 cm. In general, we find that for varying parameters the expected losses can be well approximated by one of three analytical expressions depending on the extreme value parameters. These findings reveal the complex interplay of the involved parameters and allow conclusions of fundamental relevance. For instance, we show that the damage always increases faster than the sea level rise itself. This in turn can be of great importance for the assessment of sea level rise impacts on the global scale. Our results are accompanied by an assessment of uncertainty, which reflects the stochastic nature of extreme events. While the uncertainty of flood damage increases with rising sea levels, we find that the error of our estimations in relation to the expected damage decreases.

Description: Quantification and analysis of geomorphic processes on a recultivated iron ore mine on the Italian island Elba using long-time ground-based LIDAR and photogrammetric data by an UAV Natural Hazards and Earth System Sciences Discussions, 3, 6271-6319, 2015 Author(s): F. Haas, L. Hilger, F. Neugirg, K. Umstädter, C. Breitung, P. Fischer, P. Hilger, T. Heckmann, J. Dusik, A. Kaiser, J. Schmidt, M. Della Seta, R. Rosenkranz, and M. Becht This study aims on the quantification and analysis of geomorphic processes on the barely vegetated slopes of a recultivated iron ore mine on the Italian island Elba using Terrestrial Lasercanning (TLS) and digital photogrammetry by UAV photographs over a period of 5 1/2 years. Beside this the study tried to work out the potential and the limitations of both methods to detect surface changes by geomorphic process dynamic within a natural environment. Both, UAV and TLS show the pattern of the erosion and accumulation processes on the investigated slope quite well, but the calculated amounts differ clearly between the methods. The reasons for these differences could be found in the different accuracies (variable level of detections) of the methods and the different viewing geometries. Both effects have an impact on the detectable process dynamic over different time scales on the slope and their calculated amounts, which in both cases can lead to an underestimation of erosion and accumulation by fluvial processes.

Description: Approaches for delineating landslide hazard areas using receiver operating characteristic in an advanced calibrating precision soil erosion model Natural Hazards and Earth System Sciences Discussions, 3, 6321-6349, 2015 Author(s): P. T. Ghazvinei, J. Zandi, J. Ariffin, R. B. Hashim, S. Motamedi, N. Aghamohammadi, and D. A. Moghaddam Soil erosion is undesirable natural event that causes land degradation and desertification. Identify the erosion-prone areas is a major component of preventive measures. Recent landslide damages at different regions lead us to develop a model of the erosion susceptibility map using empirical method (RUSLE). A landslide-location map was established by interpreting satellite image. Field observation data was used to validate the intensity of soil erosion. Further, a correlation analysis was conducted to investigate the "Receiver Operating Characteristic" and frequency ratio. Results showed a satisfactory correlation between the prepared RUSLE-based soil erosion map and actual landslide distribution. The proposed model can effectively predict the landslide events in soil-erosion area. Such a reliable predictive model is an effective management facility for the regional landslide forecasting system.

Description: Maximum wind radius estimated by the 50 kt radius: improvement of storm surge forecasting over the Western North Pacific Natural Hazards and Earth System Sciences Discussions, 3, 6431-6457, 2015 Author(s): H. Takagi and W. Wu Even though the maximum wind radius ( R max ) is an important parameter in determining the intensity and size of tropical cyclones, it has been overlooked in previous storm surge studies. This research reviewed the existing estimation methods of R max based on the central pressure or maximum wind speed. These over or underestimated R max because of the substantial variety of the data, though an average radius could be moderately estimated. Alternatively, we proposed an R max estimation method based on the radius of the 50 knot wind ( R 50 ). The data obtained during the passage of strong typhoons by a meteorological station network in the Japanese archipelago enabled us to derive the following formula, R max = 0.23 R 50 . Although this new method substantially improved the estimation of R max compared to the existing models, an estimation error was unavoidable because of fundamental uncertainties regarding the typhoon's structure or insufficient number of available typhoon data. In fact, a numerical simulation from 2013 Typhoon Haiyan demonstrated a substantial difference in the storm surge height for different R max . Therefore, the variability of R max should be taken into account in storm surge simulations, independently of the model used, to minimize the risk of over or underestimation of storm surges. The proposed method is expected to increase the reliability of storm surge prediction and contribute to disaster risk management, particularly in the Western North Pacific, including countries such as Japan, China, Taiwan, Philippines, and Vietnam.

Description: Characteristics of landslides in unwelded pyroclastic flow deposits, southern Kyushu, Japan Natural Hazards and Earth System Sciences Discussions, 3, 6351-6378, 2015 Author(s): M. Yamao, R. C. Sidle, T. Gomi, and F. Imaizumi We investigated 184 landslides that occurred in unwelded pyroclastic flow deposits (Shirasu) on southern Kyushu Island, Japan, that included detailed data on the rainfall characteristics and the timing of slope failure. Localized rainfall intensity, antecedent rainfall, and topography affected the hydrologic processes that triggered landslides. Antecedent rainfall (adjusted for evapotranspiration losses) for large (〉 200 mm) storms that triggered landslides was much lower than for smaller (≤ 200 mm) storms. Mean storm intensity and antecedent 7 day rainfall (API 7 ) thresholds of 〉 5 mm h -1 and ≤ 30 mm (or API 30 ≤ 60 mm), respectively, were useful to identify landslides triggered by rapid pore water pressure response, especially for shorter ( 〈 20 h) duration events. During smaller storms with lower intensity, landslides are likely affected by a combined increase in soil weight and loss of suction when API 30 ≥ 150 mm; simulations indicated that these weight and suction changes due to rainfall accumulation decreased factor of safety in steep Shirasu slopes, but did not necessarily trigger the landslides. All but two of the 21 landslides that plotted below a general rainfall intensity-duration threshold for landslide initiation had API 30 values 〉 235 mm, indicating that they were highly influenced by the combined effects of the accumulated weight of rainfall and loss of suction. Our findings show that both event rainfall characteristics and antecedent conditions affect the hydrogeomorphic processes that trigger different types of landslides in Shirasu. This knowledge and the thresholds we have identified are useful for predicting the occurrence of different types of landslides in Shirasu deposits and improving sediment disaster prevention practices, including real-time warning systems.

Description: Ensemble flood forecasting to support dam water release operation using 10 and 2 km-resolution JMA Nonhydrostatic Model ensemble rainfalls Natural Hazards and Earth System Sciences Discussions, 3, 7411-7456, 2015 Author(s): K. Kobayashi, S. Otsuka, Apip, and K. Saito This paper presents a study on short-term ensemble flood forecasting specifically for small dam catchments in Japan. Numerical ensemble simulations of rainfall from the Japan Meteorological Agency Nonhydrostatic Model are used as the input data to a rainfall–runoff model for predicting river discharge into a dam. The ensemble weather simulations use a conventional 10 km and a high-resolution 2 km spatial resolution. A distributed rainfall–runoff model is constructed for the Kasahori dam catchment (approx. 70 km 2 ) and applied with the ensemble rainfalls. The results show that the hourly maximum and cumulative catchment-average rainfalls of the 2 km-resolution JMA-NHM ensemble simulation are more appropriate than the 10 km-resolution rainfalls. All the simulated inflows based on the 2 and 10 km rainfalls become larger than the flood discharge of 140 m 3 s −1 ; a threshold value for flood control. The inflows with the 10 km-resolution ensemble rainfall are all considerably smaller than the observations, while, at least one simulated discharge out of 11 ensemble members with the 2 km-resolution rainfalls reproduces the first peak of the inflow at the Kasahori dam with similar amplitude to observations, although there are spatiotemporal lags between simulation and observation. To take positional lags into account of the ensemble discharge simulation, the rainfall distribution in each ensemble member is shifted so that the catchment-averaged cumulative rainfall of the Kasahori dam maximizes. The runoff simulation with the position-shifted rainfalls show much better results than the original ensemble discharge simulations.

Description: Importance of three-dimensional grids and time-dependent factors for the applications of earthquake forecasting models to subduction environments Natural Hazards and Earth System Sciences Discussions, 3, 7527-7553, 2015 Author(s): C.-H. Chan This study provides some new insights into earthquake forecasting models to the regions with subduction systems, including the depth-component for forecasting grids and time-dependent factors. To manifest the importance of depth-component, I incorporate three-dimensional grids into forecasting approaches and compare with those with two-dimensional cells. Through applications to the two subduction regions, Ryukyu and Kanto, the approaches with three-dimensional grids always obtain better forecasting ability. I thus confirm the importance of depth-dependency for forecasting, especially for the applications to a subduction environment or a region with non-vertical seismogenic structures. In addition, I discuss the role of time-dependent factors for forecasting models. I conclude that time-dependency becomes crucial only when significant seismicity rate change follows a large earthquake. The insights into the applications of forecasting models could provide key information regarding seismic and tsunami hazard assessments.

Description: The observed clustering of damaging extra-tropical cyclones in Europe Natural Hazards and Earth System Sciences Discussions, 3, 7457-7486, 2015 Author(s): S. Cusack The clustering of severe European windstorms on annual timescales has substantial impacts on the re/insurance industry. Management of the risk is impaired by large uncertainties in estimates of clustering from historical storm datasets typically covering the past few decades. The uncertainties are unusually large because clustering depends on the variance of storm counts. Eight storm datasets are gathered for analysis in this study in order to reduce these uncertainties. Six of the datasets contain more than 100~years of severe storm information to reduce sampling errors, and the diversity of information sources and analysis methods between datasets sample observational errors. All storm severity measures used in this study reflect damage, to suit re/insurance applications. It is found that the shortest storm dataset of 42 years in length provides estimates of clustering with very large sampling and observational errors. The dataset does provide some useful information: indications of stronger clustering for more severe storms, particularly for southern countries off the main storm track. However, substantially different results are produced by removal of one stormy season, 1989/1990, which illustrates the large uncertainties from a 42-year dataset. The extended storm records place 1989/1990 into a much longer historical context to produce more robust estimates of clustering. All the extended storm datasets show a greater degree of clustering with increasing storm severity and suggest clustering of severe storms is much more material than weaker storms. Further, they contain signs of stronger clustering in areas off the main storm track, and weaker clustering for smaller-sized areas, though these signals are smaller than uncertainties in actual values. Both the improvement of existing storm records and development of new historical storm datasets would help to improve management of this risk.

Description: An extended stochastic method for seismic hazard estimation Natural Hazards and Earth System Sciences Discussions, 3, 7555-7586, 2015 Author(s): A. K. Abd el-aal, M. A. El-Eraki, and S. I. Mostafa In this contribution, we developed an extended stochastic technique for seismic hazard assessment purposes. This technique depends on the hypothesis of stochastic technique of Boore (2003) "Simulation of ground motion using the stochastic method. Appl. Geophy. 160:635–676". The essential characteristics of extended stochastic technique are to obtain and simulate ground motion in order to minimize future earthquake consequences. The first step of this technique is defining the seismic sources which mostly affect the study area. Then, the maximum expected magnitude is defined for each of these seismic sources. It is followed by estimating the ground motion using an empirical attenuation relationship. Finally, the site amplification is implemented in calculating the peak ground acceleration (PGA) at each site of interest. We tested and applied this developed technique at Cairo, Suez, Port Said, Ismailia, Zagazig and Damietta cities to predict the ground motion. Also, it is applied at Cairo, Zagazig and Damietta cities to estimate the maximum peak ground acceleration at actual soil conditions. In addition, 0.5, 1, 5, 10 and 20 % damping median response spectra are estimated using the extended stochastic simulation technique. The calculated highest acceleration values at bedrock conditions are found at Suez city with a value of 44 cm s −2 . However, these acceleration values decrease towards the north of the study area to reach 14.1 cm s −2 at Damietta city. This comes in agreement with the results of previous studies of seismic hazards in northern Egypt and is found to be comparable. This work can be used for seismic risk mitigation and earthquake engineering purposes.

Description: The importance of erosion for debris flow runout modelling from applications to the Swiss Alps Natural Hazards and Earth System Sciences Discussions, 3, 2379-2417, 2015 Author(s): F. Frank, B. W. McArdell, C. Huggel, and A. Vieli This study describes an investigation of channel-bed erosion of sediment by debris flows. An erosion model, developed using field data from debris flows at the Illgraben catchment, Switzerland, was incorporated into the existing RAMMS debris-flow model, which solves the 2-D shallow-water equations for granular flows. In the erosion model, the relationship between maximum shear stress and measured erosion is used to determine the maximum potential erosion depth. Additionally, the maximum rate of erosion, measured at the same field site, is used to constrain the erosion rate. The model predicts plausible erosion values in comparison with field data from highly erosive debris flow events at the Spreitgraben torrent channel, Switzerland in 2010, without any adjustment to the coefficients in the erosion model. We find that by including channel erosion in runout models a more realistic flow pattern is produced than in simulations where entrainment is not included. In detail, simulations without channel bed erosion show more lateral outflow from the channel where it has not been observed in the field. Therefore the erosion model may be especially useful for practical applications such as hazard analysis and mapping, as well as scientific case studies of erosive debris flows.

Description: Movement of the Donglingxin landslide, China, induced by reservoir inundation and rainfall Natural Hazards and Earth System Sciences Discussions, 3, 2537-2564, 2015 Author(s): J. Yu, R. B. Wang, W. Y. Xu, L. Yan, J. C. Zhang, and Q. X. Meng With numerous high mountains, deep valleys and turbulent rivers, many hydropower plants have been constructed in the south-west China. Reservoir bank slopes are very common in this area, these slopes are widespread and quite often involved in deformation that can result in serious damage and casualties. In case of the Donglingxin landslide, for an in-depth study of processes that can trigger these events, the deformation characteristics and the failure mechanisms of the slope were performed on a detail scale, based on an intensive monitoring of rainfall events, reservoir level fluctuation and groundwater movement. The deformation of the upper part of slope is mainly induced by rainfall events, reservoir level fluctuation affects the deformation of the lower part of slope. The increase of pore water pressure may result in the failure of slope. The filed investigation suggest that the slope is unstable. Drainages is the only stabilization measure which can be implemented, due to very complex geological and geomorphology condition.

Description: Impacts of storm chronology on the morphological changes of the Formby beach and dune system, UK Natural Hazards and Earth System Sciences Discussions, 3, 2565-2597, 2015 Author(s): P. Dissanayake, J. Brown, and H. Karunarathna Impacts of storm chronology within a storm cluster on beach/dune erosion are investigated by applying the state-of-the-art numerical model XBeach to the Sefton coast, northwest England. Six temporal storm clusters of different storm chronologies were formulated using three storms observed during the 2013/14 winter. The storm power values of these three events nearly halve from the first to second event and from the second to third event. Cross-shore profile evolution was simulated in response to the tide, surge and wave forcing during these storms. The model was first calibrated against the available post-storm survey profiles. Cumulative impacts of beach/dune erosion during each storm cluster were simulated by using the post-storm profile of an event as the pre-storm profile for each subsequent event. For the largest event the water levels caused noticeable retreat of the dune toe due to the high water elevation. For the other events the greatest evolution occurs over the bar formations (erosion) and within the corresponding troughs (deposition) of the upper beach profile. The sequence of events impacting the size of this ridge-runnel feature is important as it consequently changes the resilience of the system to the most extreme event that causes dune retreat. The highest erosion during each single storm event was always observed when that storm initialised the storm cluster. The most severe storm always resulted in the most erosion during each cluster, no matter when it occurred within the chronology, although the erosion volume due to this storm was reduced when it was not the primary event. The greatest cumulative cluster erosion occurred with increasing storm severity; however, the variability in cumulative cluster impact over a beach/dune cross-section due to storm chronology is minimal. Initial storm impact can act to enhance or reduce the system resilience to subsequent impact, but overall the cumulative impact is controlled by the magnitude and number of the storms. This model application provides inter-survey information about morphological response to repeated storm impact. This will inform local managers of the potential beach response and dune vulnerability to variable storm configurations.

Description: Mobile Augmented Reality in support of building damage and safety assessment Natural Hazards and Earth System Sciences Discussions, 3, 2599-2627, 2015 Author(s): W. Kim, N. Kerle, and M. Gerke Rapid and accurate assessment of the state of buildings in the aftermath of a disaster event is critical for an effective and timely response. For rapid damage assessment of buildings, the utility of remote sensing (RS) technology has been widely researched, with focus on a range of platforms and sensors. However, RS-based approach still have limitations to assess structural integrity and the specific damage status of individual buildings. Consequently, ground-based assessment conducted by structural engineers and first responders is still required. This paper demonstrates the concept of mobile Augmented Reality (mAR) to improve performance of building damage and safety assessment in situ. Mobile AR provides a means to superimpose various types of reference or pre-disaster information (virtual data) on actual post-disaster building data (real building). To adopt mobile AR, this study defines a conceptual framework based on Level of Complexity (LOC). The framework consists of four LOCs, and for each of these the data types, required processing steps, AR implementation, and use for damage assessment, are described. Based on this conceptualization we demonstrate prototypes of mAR for both indoor and outdoor purposes. Finally, we conduct a user evaluation of the prototypes to validate the mAR approach for building damage and safety assessment.

Description: Infrasound array criteria for automatic detection and front velocity estimation of snow avalanches: towards a real-time early-warning system Natural Hazards and Earth System Sciences Discussions, 3, 2709-2737, 2015 Author(s): E. Marchetti, M. Ripepe, G. Ulivieri, and A. Kogelnig Avalanche risk management is strongly related to the ability to identify and timely report the occurrence of snow avalanches. Infrasound has been applied to avalanche research and monitoring for the last 20 years but it never turned into an operational tool for the ambiguity to identify clear signals related to avalanches. We present here a new method based on the analysis of infrasound signals recorded by a small aperture array in Ischgl (Austria), which overcome now this limit. The method is based on array derived wave parameters, such as back-azimuth and apparent velocity. The method defines threshold criteria for automatic avalanche identification considering avalanches as a moving source of infrasound. We validate efficiency of the automatic infrasound detection with continuous observations with Doppler Radar and we show how dynamics parameters such as the velocity of a snow avalanche in any given path around the array can be efficiently derived. Our results indicate that a proper infrasound array analysis allows a robust, real-time, remote detection of snow avalanches that could thus contribute significantly to avalanche forecast and risk management.

Description: The dark side of risk and crisis communication: legal conflicts and responsibility allocation Natural Hazards and Earth System Sciences Discussions, 3, 2739-2756, 2015 Author(s): A. Scolobig Inadequate, misinterpreted or missing risk and crisis communication may be a reason for practitioners, and sometimes even science advisors, to become subjects of criminal charges. This work discusses the legal consequences of communication. After presenting some cases, the discussion focuses on three critical issues: the development of effective communication protocols; the role, tasks and responsibilities of science advisors; and the collateral effects of practitioners' defensive behaviours. For example, if the avoidance of personal liability becomes a primary objective for practitioners, it may clash with other objectives, such as the protection of vulnerable communities or the transparency of decision-making. The conclusion presents some ideas for future research on the legal aspects of risk communication.

Description: Attributing trends in extremely hot days to changes in atmospheric dynamics Natural Hazards and Earth System Sciences Discussions, 3, 3323-3367, 2015 Author(s): J. A. García-Valero, J. P. Montávez, J. J. Gómez-Navarro, and P. Jiménez-Guerrero This paper proposes a method that allows the detection of trends in the frequency of extreme events and its attribution to changes in atmospheric dynamics characterized through Circulation Types (CTs). The method is applied to summer Extremely Hot Days (EHD) in Spain during the period 1958–2008. For carrying out this exercise, regional series of daily maximum temperature are derived from the regional dataset Spain02. Eight regions with different daily maximum temperature variability are identified. All of them exhibit important trends in the occurrence of EHDs, especially in inner regions. Links between the probability of EHD occurrence in the regions and CTs have been calculated. Furthermore, the consistency of the results to the atmospheric variables used in defining the CTs is analyzed. Sea Level Pressure (SLP), Temperature at 850 hPa Level (T850) and Geopotential Height at 500 hPa Level (Z500) from the ERA40 dataset have been used for the six CT classifications obtained using the variables separately and in different combinations of pairs. The optimum choice of large scale variables depends on the region under consideration, being the combination SLP-T850 the one giving the most suitable characterization for most of them. Finally, an attribution exercise of the regional EHD trends to the dynamics is proposed. Results show that the maximum of attributable EHD trends to changes in dynamics in every region is always below 5 %, being even lower than 20% in those regions with the largest EHD trends, mainly located in the center of the Iberian Peninsula (IP).

Description: Review Article: Explosive cyclogenesis over the south-east of Romania 2–3 December 2012 Natural Hazards and Earth System Sciences Discussions, 3, 3449-3485, 2015 Author(s): M. Bratu and C. Nichita This paper is devoted to the study of the synoptic-dynamical conditions that contributed to the development of a rare explosive cyclogenesis event that occurred at the beginning of the winter from 2012 to 2013 in south-eastern Romania, more precisely between 2 and 3 December 2012. The minimum sea level pressure observed was 980.2 hPa, the lowest ever observed record for the surface of the Sulina weather station, and also over the western side of the Black Sea during the of period 1961–2000 and 1965–2004. It was found that the cyclone was not a regular one, but a real "meteorological bomb" one, where the central pressure at sea level recorded an extraordinary decrease at about 32.3 hPa in 24 h, equivalent with 1.7 B (Bergeron unit). Compared to the 20th century storms named Lothar and Martin (level 2 and 1 on the hurricane scale) which devastated western and central Europe in December 1999, this case of explosive cyclogenesis can be considered one of the most extreme for our area, from both a meteorological view as well as its effects.

Description: Can an early warning system help minimize the impacts of coastal storms? A case study of the 2012 Halloween storm, Northern Italy Natural Hazards and Earth System Sciences Discussions, 3, 3409-3448, 2015 Author(s): M. D. Harley, A. Valentini, C. Armaroli, L. Perini, L. Calabrese, and P. Ciavola The Emilia-Romagna Early Warning System (ER-EWS) is a state-of-the-art coastal forecasting system that comprises a series of numerical models (COSMO, ROMS, SWAN and XBeach) to obtain a daily three-day forecast of coastal storm hazard at eight key sites along the Emilia-Romagna coastline (Northern Italy). On the night of 31 October 2012, a major storm event occurred that resulted in elevated water levels (equivalent to a 1-in-20 to 1-in-50-year event) and widespread erosion and flooding. Since this storm happened just one month prior to the roll-out of the ER-EWS, the forecast performance related to this event is unknown. The aim of this study was to therefore reanalyse the ER-EWS as if it had been operating a day before the event and determine to what extent the forecasts may have helped reduce storm impacts. Three different reanalysis modes were undertaken: (1) a default forecast (DF) mode based on three-day wave and water-level forecasts and default XBeach parameters, (2) a "perfect" offshore (PO) forecast mode using measured offshore values and default XBeach parameters; and (3) a calibrated XBeach (CX) mode using measured offshore values and an optimized parameter set obtained through an extensive calibration process. The results indicate that while a "code red" alert would have been issued for the DF mode, an underprediction of the extreme water levels of this event limited high-hazard forecasts to only two of the eight ER-EWS sites. Forecasts based on measured offshore conditions (the PO mode) more-accurately indicate high hazard conditions for all eight sites. Further considerable improvements are observed using an optimized XBeach parameter set (the CX mode) compared to default parameters. A series of what-if scenarios at one of the sites show that artificial dunes, which are a common management strategy along this coastline, could have hypothetically been constructed as an emergency procedure to potentially reduce storm impacts.

Description: Hazard impact on settlements: the role of urban and structural morphology Natural Hazards and Earth System Sciences Discussions, 3, 3287-3321, 2015 Author(s): M. Bostenaru Dan and I. Armas We aim to create an alternative to GIS representation of the impact of hazards on urban areas. To accomplish this, we revise the traditional map, so that it can cope with today's innovative ways of planning, namely strategic planning. As in the theory of fractals, we address the building dimension and the urban neighbourhood dimension as different geographic scales between which lessons for decisions can be learned through regression. The interaction between the two scales can be seen when looking for alternatives or the completion of a GIS analysis, or in chosing the landmarks, which, in the case of hazards, become strategic elements in strategic planning. A methodology to innovate mapping as a digital means for analysing and visualising the impact of hazards has been developed. This new method relies on concepts from various geography, urban planning, structural engineering and architecture approaches related to disaster management. The method has been tested at the building scale for the central N–S boulevard in Bucharest, Romania, comprising the protected urban zone 04 "Magheru". At the urban scale, an incident database has been created, in which the case study for the building level can be mapped. The paper presented is part of a larger research work, which addresses decision making using the framework shown here. The main value of the paper is in proposing a conceptual framework to deconstruct the map for digital disaster impact analysis and representation. This concept is highly original, because it considers the representation of elements at different scales to be of different importance in the urban tissue, according to the analysis to be performed on them.

Description: The effect of uncertainty in earthquake fault parameters on the maximum wave height from a tsunami propagation model Natural Hazards and Earth System Sciences Discussions, 3, 3369-3408, 2015 Author(s): D. Burbidge, C. Mueller, and W. Power Over the last decade tsunami propagation models have been used extensively for both tsunami forecasting and hazard and risk assessment. However, the effect of uncertainty in the earthquake source parameters on the results of the tsunami model has not always been examined in great detail. Here we have undertaken a systematic study of the uncertainty in the maximum wave height of a tsunami ( h max ) as a function of the uncertainty in the rupture parameters of the earthquake that generates it (specifically the strike, dip, rake, depth and magnitude). We have shown that even for the simple case of a tsunami propagating over flat bathymetry, the Coefficient of Variation (CoV) and skewness of the distribution of h max was a complex function of the choice of rupture parameter, distance and azimuth. The relationships became even more complex as the bathymetry used became more realistic. This has major potential implications for both how warning centres operate in the future and how the uncertainty in parameters describing the source should be incorporated into future probabilistic tsunami hazard assessments.

Description: Scenario-based numerical modelling and the palaeo-historic record of tsunamis in Wallis and Futuna, Southwest Pacific Natural Hazards and Earth System Sciences Discussions, 3, 2283-2346, 2015 Author(s): G. Lamarche, S. Popinet, B. Pelletier, J. Mountjoy, J. Goff, S. Delaux, and J. Bind We investigated the tsunami hazard in the remote French territory of Wallis and Futuna, Southwest Pacific, using the Gerris flow solver to produce numerical models of tsunami generation, propagation and inundation. Wallis consists of the inhabited volcanic island of Uvéa that is surrounded by a lagoon delimited by a barrier reef. Futuna and the island of Alofi forms the Horn Archipelago located ca. 240 km east of Wallis. They are surrounded by a narrow fringing reef. Futuna and Alofi emerge from the North Fiji Transform Fault that marks the seismically active Pacific-Australia plate boundary. We generated fifteen tsunami scenarios. For each, we calculated maximum wave elevation (MWE), inundation distance, and Expected Time of Arrival (ETA). The tsunami sources were local, regional and distant earthquake faults located along the Pacific Rim. In Wallis, the outer reef may experience 6.8 m-high MWE. Uvéa is protected by the barrier reef and the lagoon, but inundation depths of 2–3 m occur in several coastal areas. In Futuna, flow depths exceeding 2 m are modelled in several populated areas, and have been confirmed by a post-September 2009 South Pacific tsunami survey. The channel between the islands of Futuna and Alofi amplified the 2009 tsunami, which resulted in inundation distance of almost 100 m and MWE of 4.4 m. This first-ever tsunami hazard modelling study of Wallis and Futuna compares well with palaeotsunamis recognised on both islands and observation of the impact of the 2009 South Pacific tsunami. The study provides evidence for the mitigating effect of barrier and fringing reefs from tsunamis.

Description: Geo-hydrological hazard and urban development in the Mediterranean area: an example from Genoa City (Italy) Natural Hazards and Earth System Sciences Discussions, 3, 2451-2492, 2015 Author(s): F. Faccini, F. Luino, A. Sacchini, L. Turconi, and J. V. De Graff The Ligurian area has always suffered from significant geo-hydrological events causing casualties and serious damage. The atmospheric circulation in autumn and winter coupled with landform peculiarities are the main causes this hazard becoming a risk to human life, structures, and infrastructures. Genoa city and the surrounding metropolitan area are commonly subject to heavy rainfall that induces violent flash floods and many shallow landslides. The most recent rainfall events occurred on 9–10 October and 15 November 2014, again causing loss of human lives and widespread damage. A troubling trend since the beginning of the new century, is the recurrence of such events with greater frequency than in the past. The city of Genoa serves as a very interesting case-study for geo-hydrological risks. Cloudbursts of few hours seem to have a rainfall intensity basically greater than in the past; that causes increase of hydrometric levels of the watercourses that quickly reach alarming values close to the overflowing. This meteorological factor, added to growing urbanization of the valley floors and slopes located north of Genoa, has inevitably produced a general trend of increasing risk for the city. Urbanization is particularly notable for the narrowing process in all cross-sections of Genoa's watercourses, both in the main ones and in the secondary streams that flow directly into the Gulf of Genoa. The narrowing of the sections resulted from the increasing demand for new spaces owing to both industrial development (which started initially at the coastal areas of Genoa), and the growth of the Genoa population. The number of inhabitants grew from fewer than 200 000 at the beginning of the 19th century tool a peak of over 800 000 in the 1970s modifying the water balance of the basins and increasing the geo-hydrological risk in an unacceptable way. Among the important topics analyzed in this paper are: (i) the meteorological characteristics of these events, (ii) the changes in the rate of daily precipitation, and (iii) the most significant periods of the urban land development determining important changes of the territory above all on the hydrographic network.

Description: Recent trends in daily rainfall extremes over Montenegro (1951–2010) Natural Hazards and Earth System Sciences Discussions, 3, 2347-2377, 2015 Author(s): D. Burić, J. Luković, B. Bajat, M. Kilibarda, and V. Ducić More intense rainfall may cause a range of negative impacts upon society and the environment. In this study we analyzed trends in extreme ETCCDI (Expert Team on Climate Change Detection and Indices) rainfall indices in Montenegro for the period 1951–2010. Montenegro has been poorly studied in terms of rainfall extremes, yet it contains the wettest Mediterranean region known as Krivošije. Several indices of precipitation extremes were assessed including the number of dry days and rainfall totals, and their trends to identify possible changes. The results generally suggest that the number of days with precipitation decreased while rainfall intensity increased particularly in south-western parts of the country. A slight tendency towards intense rainfall events is suggested. Calculated trends for each index are spatially presented and examined using a plotGoogleMaps software package. This study also examined spatial pattern of relationship between extreme rainfall indices and North Atlantic Oscillation. Results suggested negative, mainly statistically significant correlations at annual, winter and autumn scale.

Description: The hostel or the warehouse? Spatiotemporal exposure assessment for natural hazards Natural Hazards and Earth System Sciences Discussions, 3, 2419-2449, 2015 Author(s): S. Fuchs, M. Keiler, and A. Zischg A spatially explicit object-based temporal assessment of buildings and citizens exposed to natural hazards in Austria is presented, including elements at risk to river flooding, torrential flooding, and snow avalanches. It is shown that the repeatedly-stated assumption of increasing losses due to continued population growth and related increase in assets has to be opposed to the local development of building stock. While some regions have shown a clearly above-average increase in assets, other regions were characterised by a below-average development. This mirrors the topography of the country, but also the different economic activities. While hotels and hostels are extraordinary prone to mountain hazards, commercial buildings as well as buildings used for recreation purpose are considerably exposed to river flooding. Residential buildings have shown an average exposure, compared to the amount of buildings of this type in the overall building stock. In sum, around 5% of all buildings are exposed to mountain hazards, and around 9% to river flooding, with around 1% of the buildings stock being multi-exposed. It is shown that the dynamics of elements at risk exposed have a time lag once land use regulations are enforced, and it is concluded that an object-based assessment has clear advantages compared to the assessment using aggregated land use data.

Description: Assessment and comparison of extreme sea levels and waves during the 2013/2014 storm season in two UK coastal regions Natural Hazards and Earth System Sciences Discussions, 3, 2665-2708, 2015 Author(s): M. P. Wadey, J. M. Brown, I. D. Haigh, T. Dolphin, and P. Wisse The extreme sea levels and waves experienced around the UK's coast during the 2013/2014 winter caused extensive coastal flooding and damage. In such circumstances, coastal managers seek to place such extremes in relation to the anticipated standards of flood protection, and the long-term recovery of the natural system. In this context, return periods are often used as a form of guidance. We therefore provide these levels for the winter storms, as well as discussing their application to the given data sets and case studies (two UK case study sites: Sefton, northwest England; and Suffolk, east England). We use tide gauge records and wave buoy data to compare the 2013/2014 storms with return periods from a national dataset, and also generate joint probabilities of sea level and waves, incorporating the recent events. The UK was hit at a national scale by the 2013/2014 storms, although the return periods differ with location. We also note that the 2013/2014 high water and waves were extreme due to the number of events, as well as the extremity of the 5 December 2013 "Xaver" storm, which had a very high return period at both case study sites. Our return period analysis shows that the national scale impact of this event is due to its coincidence with spring high tide at multiple locations as the tide and storm propagated across the continental shelf. Given that this event is such an outlier in the joint probability analyses of these observed data sets, and that the season saw several events in close succession, coastal defences appear to have provided a good level of protection. This type of assessment should be recorded alongside details of defence performance and upgrade, with other variables (e.g. river levels at estuarine locations) included and appropriate offsetting for linear trends (e.g. mean sea level rise) so that the storm-driven component of coastal flood events can be determined. Local offsetting of the mean trends in sea level allows long-term comparison of storm severity and also enables an assessment of how sea level rise is influencing return levels over time, which is important when considering long-term coastal resilience in strategic management plans.

Description: Estimating flood damage to railway infrastructure – the case study of the March River flood in 2006 at the Austrian Northern Railway Natural Hazards and Earth System Sciences Discussions, 3, 2629-2663, 2015 Author(s): P. Kellermann, A. Schöbel, G. Kundela, and A. H. Thieken Models for estimating flood losses to infrastructure are rare and their reliability is seldom investigated although infrastructure losses might contribute considerably to the overall flood losses. In this paper, a statistical modelling approach for estimating direct structural flood damage to railway infrastructure and associated financial losses is presented. Via a combination of empirical data, i.e. photo-documented damage on the Northern Railway in Lower Austria caused by the March river flood in 2006, and simulated flood characteristics, i.e. water levels, flow velocities and combinations thereof, the correlations between physical flood impact parameters and damage occurred to the railway track were investigated and subsequently rendered into a damage model. After calibrating the loss estimation using recorded repair costs of the Austrian Federal Railways, the model was applied to three synthetic scenarios with return periods of 30, 100 and 300 years of March river flooding. Finally, the model results are compared to depth-damage curve based approaches for the infrastructure sector obtained from the Rhine Atlas damage model and the Damage Scanner model. The results of this case study indicate a good performance of our two-stage model approach. However, due to a lack of independent event and damage data, the model could not yet be validated. Future research in natural risk should focus on the development of event and damage documentation procedures to overcome this significant hurdle in flood damage modelling.

Description: Brief Communication: On the rapid and efficient monitoring results dissemination in landslide emergency scenarios: the Mont de La Saxe case study Natural Hazards and Earth System Sciences Discussions, 3, 2757-2775, 2015 Author(s): D. Giordan, A. Manconi, P. Allasia, and D. Bertolo Straightforward communication of monitoring results is of major importance in emergency scenarios relevant to large slope instabilities. Here we describe the communication strategy developed for the Mont de La Saxe case study, a large rockslide threatening La Palud and Entrèves hamlets in the Courmayeur municipality (Aosta Valley, Italy). Starting from the definition of actions and needs of the Landslide Management Team, including scientists, technicians, civil protection operators, decision makers, and politicians, we show that sharing and disseminating ad hoc information simplifies the understanding of the landslide evolution, as well as the correct communication of the level of criticality.

Description: A dynamic landslide hazard assessment system for Central America and Hispaniola Natural Hazards and Earth System Sciences Discussions, 3, 2847-2882, 2015 Author(s): D. B. Kirschbaum, T. Stanley, and J. Simmons Landslides pose a serious threat to life and property in Central America and the Caribbean Islands. In order to allow regionally coordinated situational awareness and disaster response, an online decision support system was created. At its core is a new flexible framework for evaluating potential landslide activity in near real-time: Landslide Hazard Assessment for Situational Awareness. This framework was implemented in Central America and the Caribbean by integrating a regional susceptibility map and satellite-based rainfall estimates into a binary decision tree, considering both daily and antecedent rainfall. Using a regionally distributed, percentile-based threshold approach, the model outputs a pixel-by-pixel nowcast in near real-time at a resolution of 30 arcsec to identify areas of moderate and high landslide hazard. The daily and antecedent rainfall thresholds in the model are calibrated using a subset of the Global Landslide Catalog in Central America available for 2007–2013. The model was then evaluated with data for 2014. Results suggest reasonable model skill over Central America and poorer performance over Hispaniola, due primarily to the limited availability of calibration and validation data. The landslide model framework presented here demonstrates the capability to utilize globally available satellite products for regional landslide hazard assessment. It also provides a flexible framework to interchange the indiviual model components and adjust or calibrate thresholds based on access to new data and calibration sources. The availability of free, satellite-based near real-time rainfall data allows the creation of similar models for any study area with a spatiotemporal record of landslide events. This method may also incorporate other hydrological or atmospheric variables such as numerical weather forecasts or satellite-based soil moisture estimates within this decision tree approach for improved hazard analysis.

Description: Review Article: A review and critical analysis of the efforts towards urban flood reduction in the Lagos region of Nigeria Natural Hazards and Earth System Sciences Discussions, 3, 3897-3923, 2015 Author(s): U. C. Nkwunonwo, M. Whitworth, and B. Baily Urban flooding has been and will continue to be a significant problem for many cities across the developed and developing world. Crucial to the amelioration of the effects of these floods is the need to develop a knowledge base of the magnitude and frequency of these floods. Within the area of flood research, attempts are being made to gain a better understanding of the causes, impacts and pattern of urban flooding as an aid to reducing the risks it poses. This research reviews flood risk within the Lagos area of Nigeria over the period 1968–2012. During this period, floods have caused harm to millions of people physically, emotionally and economically. Arguably over this period the efforts of stakeholders to address the challenges appear to have been limited by, among other things, lack of reliable data, lack of awareness among the population affected, and lack of knowledge of flood risk mitigation. It is the aim of this research to assess the current understanding of flood risk and management in Lagos and to offer recommendations towards future guidance.

Description: Railway deformation detected by DInSAR over active sinkholes in the Ebro Valley evaporite karst, Spain Natural Hazards and Earth System Sciences Discussions, 3, 3967-3981, 2015 Author(s): J. P. Galve, C. Castañeda, and F. Gutiérrez Previously not measured subsidence on railway tracks was detected using DInSAR displacement maps produced for the central sector of Ebro Valley (NE Spain). This area is affected by evaporite karst and the analyzed railway corridors traverse active sinkholes that produce deformations in these infrastructures. One of the railway tracks affected by slight settlements corresponds to the Madrid–Barcelona high-speed line, a transport infrastructure highly vulnerable to ground deformation processes. Our analysis based on DInSAR measurements and geomorphological surveys indicate that this line show dissolution-induced subsidence and compaction of anthropogenic deposits (infills and embankments). By using DInSAR techniques, it was also measured the significant subsidence related to the activity of sinkholes in the Castejón–Zaragoza conventional railway line. Thus, this study demonstrate that DInSAR velocity maps coupled with detailed geomorphological surveys may help in the identification of the sectors of railway tracks that may compromise the safety of travellers.

Description: Brief Communication: Sendai Framework for Disaster Risk Reduction – success or warning sign for Paris? Natural Hazards and Earth System Sciences Discussions, 3, 3955-3966, 2015 Author(s): J. Mysiak, S. Surminski, A. Thieken, R. Mechler, and J. Aerts In March 2015, a new international blueprint for disaster risk reduction (DRR) has been adopted in Sendai, Japan, at the end of the Third UN World Conference on Disaster Risk Reduction (WCDRR, 14–18 March 2015). We review and discuss the agreed commitments and targets, as well as the negotiation leading to the Sendai Framework for DRR (SFDRR) and discuss briefly its implication for the later UN-led negotiations on sustainable development goals and climate change.

Description: Discussing the role of tropical and subtropical moisture sources in extreme precipitation events in the Mediterranean region from a climate change perspective Natural Hazards and Earth System Sciences Discussions, 3, 3983-4005, 2015 Author(s): S. O. Krichak, S. B. Feldstein, P. Alpert, S. Gualdi, E. Scoccimarro, and J.-I. Yano Extreme precipitation events in the Mediterranean region during the cool season are strongly affected by the export of moist air from tropical and subtropical areas into the extratropics. The aim of this paper is to present a discussion of the major research efforts on this subject and to formulate a summary of our understanding of this phenomenon, along with its recent past trends from a climate change perspective. The issues addressed are: a discussion of several case studies; the origin of the air moisture and the important role of atmospheric rivers for fueling the events; the mechanism responsible for the intensity of precipitation during the events, and the possible role of global warming in recent past trends in extreme weather events over the Mediterranean region.

Description: PM 10 measurements in urban settlements after lava fountain episodes at Mt Etna, Italy: pilot test to assess volcanic ash hazard on human health Natural Hazards and Earth System Sciences Discussions, 3, 3925-3953, 2015 Author(s): D. Andronico and P. Del Carlo In this paper we focus on the potential risks caused by the sub-10 micron fraction of volcanic ash (particulate matter: PM 10 ) after the basaltic explosive eruptions from Mt Etna volcano (Italy), which have dramatically increased in frequency over the last 20 years. We present results deriving from the study of the ash concentration in the air following the lava fountain episode from the New South-East Crater of Etna on 15 November 2011, which caused tephra fallout over the eastern slope of the volcano. Short-duration tests of PM 10 measurements were carried out at three different sites using a TSI® DustTrak TM aerosol monitor a few hours after the end of the eruption, and readouts of the air quality were repeated at the same sites a month later without volcanic activity. Furthermore, ash samples were characterized by grain-size, componentry, morphological and petro-chemical analyses. By comparing PM 10 levels measured a few hours after the 15 November lava fountain and on 15 December, we found that relatively low amounts (500–1500 g m -2 ) of tephra fallout cause high levels of PM 10 in the air. This is because the coarse particles, like basaltic ash, are readily broken up by traffic and hence remobilized into the air, due to their intrinsic, physical and morphological features. We believe that in the future the impact from ash fallout in the Etnean territory should receive proper attention in order to avoid potential health problems; this may be achieved by accomplishing simple but effective actions, first and foremost the prompt removal of the ash deposits from the urbanized areas.

Description: Changes in the occurrence of rainfall-induced landslides in Calabria, Southern Italy, in the 20th century Natural Hazards and Earth System Sciences Discussions, 3, 3579-3619, 2015 Author(s): S. L. Gariano, O. Petrucci, and F. Guzzetti We exploit a catalogue of 1466 rainfall events with landslides in the 90 year period 1921–2010 to study temporal and geographical variations in the occurrence of landslides in Calabria, Southern Italy. We use daily rainfall records obtained by a network of 318 rain gauges to reconstruct 448 493 rainfall events. Combining the rainfall and the landslide information, we obtain a catalogue of 1466 rainfall events with landslides (REL) in Calabria from 1921 to 2010, where a REL is the occurrence of one or more landslide during or immediately after a rainfall event. We find that the geographical and the temporal distributions of the rainfall-induced landslides have changed in the observation period. The average and the maximum values of the cumulated event rainfall that have resulted in landslides in the recent-most 30 year period 1981–2010 are lower than the values necessary to trigger landslides in previous periods, whereas the duration of the rainfall events that triggered landslides has remained the same. This can be considered evidence of variations in rainfall conditions, but also an increase in the vulnerability of the territory. We further find that the yearly distribution of rainfall-induced landslides has changed in the observation period, analysing the variations in the number of rainfall events with landslides occurred in each month in three 30 year periods. To investigate variations in the impact of REL on the population, we compared the number of REL in each of the 409 municipalities in Calabria, with the size of the population in the municipalities, measured by national Censuses conducted in 1951, 1981, and 2011. For the purpose, we adopted two strategies. The first strategy considered impact as I REL = #REL/ P and the second strategy measured impact as R REL = #REL × P , where #REL is the total number of REL in a period, and P is the size of the population in the same period and geographical area. Considering the entire observation period, I REL and R REL have both increased in Calabria. However, considering the changes between the recent period 1981–2010 and the previous period 1951–1980, results are more variegated with a number of municipalities where I REL and R REL have increased, or decreased. Municipalities where I REL has increased are mainly in the mountains, and municipalities where R REL has increased are mainly along the coasts.

Description: Seeking for key meteorological parameters to better understand Hector Natural Hazards and Earth System Sciences Discussions, 3, 3621-3653, 2015 Author(s): S. Gentile and R. Ferretti Twelve Hector events, a storm developing in the northern Australia, are analyzed to the aim of identifying the main meteorological parameters involved in the convective development. Based on Crook's ideal study \citep{Crook} wind speed and direction, wind shear, water vapor, Convective Available Potential Energy and type of convection are the parameters used for this analysis. Both European Centre for Medium-Range Weather Forecasts (ECMWF) analysis and high resolution simulations from the Fifth-Generation Mesoscale Model (MM5) are used. The MM5 simulations are used to connect the mean vertical velocity to the total condensate at the maximum stage and to study the dynamics of the storms. The ECMWF analysis are used to evaluate the initial conditions and the environmental fields contributing to Hector development. The analysis suggests that the strength of convection is largely contributing to the vertical distribution of hydrometeors. The role of total condensate and mean lifting vs. low level moisture, Convective Available Potential Energy, surface wind and direction is analyzed for shear and no-shear conditions to evaluate the differences between type A and B for real events. Results confirm the tendency suggested by Crook's analysis. On the other hand, Crook's hypothesis of low level moisture as the only parameter that differentiates between type A and B can be applied only if the events develop in the same meteorological conditions. Crook's tests also helped to asses how the the meteorological parameters contribute to Hector development in terms of percentage.

Description: Comparison of different methods for the in situ measurement of forest litter moisture content Natural Hazards and Earth System Sciences Discussions, 3, 3733-3760, 2015 Author(s): C. Schunk, B. Ruth, M. Leuchner, C. Wastl, and A. Menzel Dead fine fuel (e.g. litter) moisture content is an important parameter for both forest fire and ecological applications as it is related to ignitability, fire behavior as well as soil respiration. However, the comprehensive literature review in this paper shows that there is no easy-to-use method for automated measurements available. This study investigates the applicability of four different sensor types (permittivity and electrical resistance measuring principles) for this measurement. Comparisons were made to manual gravimetric reference measurements carried out almost daily for one fire season and overall agreement was good (highly significant correlations with 0.792 ≦ r ≦ 0.947). Standard deviations within sensor types were linearly correlated to daily sensor mean values; however, above a certain threshold they became irregular, which may be linked to exceedance of the working ranges. Thus, measurements with irregular standard deviations were considered unusable and calibrations of all individual sensors were compared for useable periods. A large drift in the sensor raw value-litter moisture-relationship became obvious from drought to drought period. This drift may be related to installation effects or settling and decomposition of the litter layer throughout the fire season. Because of the drift and the in situ calibration necessary, it cannot be recommended to use the methods presented here for monitoring purposes. However, they may be interesting for scientific studies when some manual fuel moisture measurements are made anyway. Additionally, a number of potential methodological improvements are suggested.

Description: Review Article: Atmospheric conditions inducing extreme precipitation over the Eastern and Western Mediterranean Natural Hazards and Earth System Sciences Discussions, 3, 3687-3732, 2015 Author(s): U. Dayan, K. M. Nissen, and U. Ulbrich This review discusses published studies of heavy rainfall events over the Mediterranean Basin, combining them in a more general picture of the dynamic and thermodynamic factors and processes producing heavy rain storms. It distinguishes the Western and Eastern Mediterranean in order to point at specific regional peculiarities. The crucial moisture for developing intensive convection over these regions can be originated not only from the adjacent Mediterranean Sea but also from distant upwind sources. Transport from remote sources is usually in the mid-tropospheric layers and associated with specific features and patterns of the larger scale circulations. The synoptic systems (tropical and extra-tropical) accounting for most of the major extreme precipitation events and the coupling of circulation and extreme rainfall patterns are presented. Heavy rainfall over the Mediterranean Basin is caused at times in concert by several atmospheric processes working at different atmospheric scales, such as local convection, upper-level synoptic-scale troughs, and meso-scale convective systems. Under tropical air mass intrusions, convection generated by static instability seems to play a more important role than synoptic-scale vertical motions. Locally, the occurrence of torrential rains and their intensity is dependent on factors such as temperature profiles and implied instability, atmospheric moisture, and lower-level convergence.

Description: Evaluation of a compound distribution based on weather patterns subsampling for extreme rainfall in Norway Natural Hazards and Earth System Sciences Discussions, 3, 3543-3577, 2015 Author(s): J. Blanchet, J. Touati, D. Lawrence, F. Garavaglia, and E. Paquet Simulation methods for design flood analyses require estimates of extreme precipitation for simulating maximum discharges. This article evaluates the MEWP model, a compound model based on weather pattern classification, seasonal splitting and exponential distributions, for its suitability for use in Norway. The MEWP model is the probabilistic rainfall model used in the SCHADEX method for extreme flood estimation. Regional scores of evaluation are used in a split sample framework to compare the MEWP distribution with more general heavy-tailed distributions, in this case the Multi Generalized Pareto Weather Pattern (MGPWP) distribution. The analysis shows the clear benefit obtained from seasonal and weather pattern-based subsampling for extreme value estimation. The MEWP distribution is found to have an overall better performance as compared with the MGPWP, which tends to overfit the data and lacks robustness. Finally, we take advantage of the split sample framework to present evidence for an increase in extreme rainfall in the south-western part of Norway during the period 1979–2009, relative to 1948–1978.

Description: Lightning characteristics in Eastern Mediterranean thunderstorms during different synoptic systems Natural Hazards and Earth System Sciences Discussions, 3, 3655-3685, 2015 Author(s): Y. Ben Ami, O. Altaratz, Y. Yair, and I. Koren Thunderstorms activity takes place in the Eastern Mediterranean mainly along the boreal fall and winter seasons during synoptic systems of Red Sea Trough (RST), Red Sea Trough that closed a low over the sea (RST-CL), and Cyprus Low (during fall – FCL and Winter – WCL). In this work we used the Israeli Lightning Location System ground strokes dataset (between October 2004 and December 2010) for studying the lightning strokes properties and their link to the thermodynamic conditions in each synoptic system. It is shown that the lightning activity dominates over sea during WCL and FCL systems (with maximum values of 37 strokes per 25 km 2 day −1 in WCL, and 54 in FCL) and have a dominant component over land during the RST and RST-CL days. The stronger instability (high CAPE values of 621 ± 466 J kg −1 ) during RST-CL days together with the higher altitude of the clouds' mixed-phase region (3630 ± 316 m) result in higher ground strokes density during this system (compared to all other) but lower fraction of positive ground strokes (3 ± 0.5%). In general the fraction of positive strokes was found to be positively correlated with the wind shear values in the layer between 0 and −25 °C. It increases from the 1.2 ± 1% in early fall to 17 ± 7% in late winter, (during FCL and WCL days) and can be linked to the decrease in the sea surface (and lower troposphere) temperature during those months, due to an impact on the charge centers vertical location. The diurnal cycle in the lightning activity was examined for each synoptic system. During WCL conditions no preferred times were found along the day (as it relates to the timing of frontal systems). During the fall systems (FCL and RST-CL) there is a peak in lightning activity during the morning hours, probably related to the enhanced convection driven by the convergence between the eastern land breeze and the western synoptic winds. The distributions of peak currents in FCL and WCL systems also change from fall to winter and include more strong negative and positive strokes toward the end of the winter.

Description: Sea surface temperature and torrential rains in the Valencia region: modelling the role of recharge areas Natural Hazards and Earth System Sciences Discussions, 3, 1357-1396, 2015 Author(s): F. Pastor, J. A. Valiente, and M. J. Estrela Heavy rain events are frequently recorded in the Western Mediterranean causing economic losses and even human casualties. The Western Mediterranean is a deep and almost closed sea surrounded by high mountain ranges and with little exchange of water with the Atlantic ocean. A main factor in the development of torrential rains are ocean-atmosphere exchanges of heat and moisture that can potentially destabilize air masses travelling over the sea. The study of air mass trajectories previous to the rain event permits the identification of sea areas that could probably contribute to the development or intensification of rainfall. From a previous Mediterranean sea surface temperature climatology, its spatio-temporal distribution patterns have been studied showing two main distribution modes in winter and summer and transitional regimes in spring and autumn. Hence, three heavy precipitation events, for such winter and summer sea temperature regimes and for fall transition, affecting the Valencia region have been selected to study the effect of sea surface temperature in torrential rains. Simulations with perturbed sea surface temperature in different areas along the air mass path were run to compare results with unperturbed simulation. The variation of sea surface temperature in certain areas caused significant changes in model accumulated values and its spatial distribution. Therefore, the existence of recharge areas where air–sea interaction favors the development of torrential rainfall in Valencia region has been shown. This methodology could be extended to the whole Mediterranean basin to look for such potential recharge areas. The identification of sea areas that contribute to the development or intensification of heavy rain events in the Mediterranean countries could be a useful prognosis and/or monitoring tool.

Description: Levee reliability analyses for various flood return periods – a case study in Southern Taiwan Natural Hazards and Earth System Sciences Discussions, 3, 457-495, 2015 Author(s): W.-C. Huang, H.-W. Yu, and M.-C. Weng In recent years, heavy rainfall conditions have caused damages around the world. To prevent damages by floods, levees have often been constructed in prone-to-inundation areas. This study performed reliability analyses for the Chiuliao 1st Levee located in southern Taiwan. The failure-related parameters were the water level, the scouring depth, and the in-situ friction angle. Three major failure mechanisms were considered, including the slope sliding failure of the levee, and the sliding and overturning failures of the retaining wall. When the variabilities of the in-situ friction angle and the scouring depth are considered for various flood return periods, the variations of the factor of safety (FS) for the different failure mechanisms show that the retaining wall sliding and overturning failures are more sensitive to the variability of the friction angle. When the flood return period is greater than 2 years, the levee can undergo slope sliding failure for all values of the water level difference. The results for levee stability analysis considering the variability of different parameters could assist engineers in designing the levee cross sections, especially with potential failure mechanisms in mind.

Description: Forest damage and snow avalanche flow regime Natural Hazards and Earth System Sciences Discussions, 3, 535-574, 2015 Author(s): T. Feistl, P. Bebi, M. Christen, S. Margreth, L. Diefenbach, and P. Bartelt Snow avalanches break, uproot and overturn trees causing damage to forests. The extent of forest damage provides useful information on avalanche frequency and intensity. However, impact forces depend on avalanche flow regime. In this paper, we define avalanche loading cases representing four different avalanche flow regimes: powder , intermittent , dry and wet . In the powder regime, the blast of the cloud can produce large bending moments in the tree stem because of the impact area extending over the entire tree crown. We demonstrate that intermittent granular loadings are equivalent to low-density uniform dry snow loadings under the assumption of homogeneous particle distributions. In the wet snow case, avalanche pressure is calculated using a quasi-static model accounting for the motion of plug-like wet snow flows. Wet snow pressure depends both on avalanche volume and terrain features upstream of the tree. Using a numerical model that simulates both powder and wet snow avalanches, we study documented events with forest damage. We find (1) powder clouds with velocities over 20 m s −1 can break tree stems, (2) the intermittent regime seldom controls tree breakage and (3) quasi-static pressures of wet snow avalanches can be much higher than pressures calculated using dynamic pressure formulas.

Description: Assessment of impact of mass movements on the upper Tayyah valley's bridge along Shear escarpment highway, Asir region (Saudi Arabia) using remote sensing data and field investigation Natural Hazards and Earth System Sciences Discussions, 3, 497-533, 2015 Author(s): A. M. Youssef, M. Al-Kathery, and B. Pradhan Escarpment highways, roads and mountainous areas in Saudi Arabia are facing landslide hazards that are frequently occurring from time to time causing considerable damage to these areas. Shear escarpment highway is located in the north of the Abha city. It is the most important escarpment highway in the area, where all the light and heavy trucks and vehicle used it as the only corridor that connects the coastal areas in the western part of the Saudi Arabia with the Asir and Najran Regions. More than 10 000 heavy trucks and vehicles use this highway every day. In the upper portion of Tayyah valley of Shear escarpment highway, there are several landslide and erosion potential zones that affect the bridges between tunnel 7 and 8 along the Shear escarpment Highway. In this study, different types of landslides and erosion problems were considered to access their impacts on the upper Tayyah valley's bridge along Shear escarpment highway using remote sensing data and field investigation. These landslides and erosion problems have a negative impact on this section of the highway. Results indicate that the areas above the highway and bridge level between bridge 7 and 8 have different landslides including planar, circular, rockfall failures and debris flows. In addition, running water through the gullies cause different erosional (scour) features between and surrounding the bridge piles and culverts. A detailed landslides and erosion features map was created based on intensive field investigation (geological, geomorphological, and structural analysis), and interpretation of Landsat image 15 m and high resolution satellite image (QuickBird 0.61 m), shuttle radar topography mission (SRTM 90 m), geological and topographic maps. The landslides and erosion problems could exhibit serious problems that affect the stability of the bridge. Different mitigation and remediation strategies have been suggested to these critical sites to minimize and/or avoid these problems in the future.

Description: Predictive analysis of landslide susceptibility in the Kao-Ping watershed, Taiwan under climate change conditions Natural Hazards and Earth System Sciences Discussions, 3, 575-606, 2015 Author(s): K. J. Shou, C. C. Wu, and J. F. Lin Among the most critical issues, climatic abnormalities caused by global warming also affect Taiwan significantly for the past decade. The increasing frequency of extreme rainfall events, in which concentrated and intensive rainfalls generally cause geohazards including landslides and debris flows. The extraordinary Typhoon Morakot hit Southern Taiwan on 8 August 2009 and induced serious flooding and landslides. In this study, the Kao-Ping River watershed was adopted as the study area, and the typical events 2007 Krosa Typhoon and 2009 Morakot Typhoon were adopted to train the susceptibility model. This study employs rainfall frequency analysis together with the atmospheric general circulation model (AGCM) downscaling estimation to understand the temporal rainfall trends, distributions, and intensities in the Kao-Ping River watershed. The rainfall estimates were introduced in the landslide susceptibility model to produce the predictive landslide susceptibility for various rainfall scenarios, including abnormal climate conditions. These results can be used for hazard remediation, mitigation, and prevention plans for the Kao-Ping River watershed.

Description: Uncertainty in flood damage estimates and its potential effect on investment decisions Natural Hazards and Earth System Sciences Discussions, 3, 607-640, 2015 Author(s): D. J. Wagenaar, K. M. de Bruijn, L. M. Bouwer, and H. De Moel This paper addresses the large differences that are found between damage estimates of different flood damage models. It explains how implicit assumptions in flood damage models can lead to large uncertainties in flood damage estimates. This explanation is used to quantify this uncertainty with a Monte Carlo Analysis. As input the Monte Carlo analysis uses a damage function library with 272 functions from 7 different flood damage models. This results in uncertainties in the order of magnitude of a factor 2 to 5. The resulting uncertainty is typically larger for small water depths and for smaller flood events. The implications of the uncertainty in damage estimates for flood risk management are illustrated by a case study in which the economic optimal investment strategy for a dike segment in the Netherlands is determined. The case study shows that the uncertainty in flood damage estimates can lead to significant over- or under-investments.

Description: Flood warnings in coastal areas: how do social and behavioural patterns influence alert services? Natural Hazards and Earth System Sciences Discussions, 3, 641-674, 2015 Author(s): G. Pescaroli and M. Magni Many studies discuss the economic and technical aspects of flood warnings. Less attention has been given to the social and psychological patterns that affect alert services. In particular, the literature focuses on warnings activated in river basins or marine environments without providing clear evidence of relevance to Mediterranean coastal areas, even though these are subjected to growing flood risk related to climate change. This paper is a first attempt to bridge this gap. Our research develops an in- depth analysis of the village of Cesenatico on the Adriatic Sea coast. Here the municipality adopted two complementary warning systems: a siren and an alert via Short Message Service (SMS). The analysis focuses on a survey conducted in 2011 and 2012 with 228 participants. The relationships between social and behavioural variables and warning services are investigated, and so are flood preparedness and information dissemination. Qualitative evidence from informal interviews is used to support the understanding of key responses. The conclusions show how different social and behavioural patterns can influence the effectiveness and use of warning systems, regardless of the technology adopted and the structural mitigation measures implemented. Education, training and accountability are seen to be critical elements for improvement. Finally, the statistical output is used to suggest new questions and new directions for research.

Description: Building and design defects observed in the residential sector and the types of damage observed in recent earthquakes in Turkey Natural Hazards and Earth System Sciences Discussions, 3, 697-760, 2015 Author(s): M. Tolga Çöğürcü Turkey is situated in a very active earthquake region. In the last century, several earthquakes resulted in thousands of deaths and enormous economic losses. In 1999, the Marmara earthquake had an approximate death toll of more than 20 000, and in 2011, the Van earthquake killed 604 people. In general, Turkish residential buildings have reinforced concrete structural systems. These reinforced concrete structures have several deficiencies, such as low concrete quality, non-seismic steel detailing, and inappropriate structural systems including several architectural irregularities. In this study, the general characteristics of Turkish building stock and the deficiencies observed in structural systems are explained, and illustrative figures are given with reference to Turkish Earthquake Code 2007 (TEC, 2007). The poor concrete quality, lack of lateral or transverse reinforcement in beam-column joints and column confinement zones, high stirrup spacings, under-reinforced columns and over-reinforced beams are the primary causes of failures. Other deficiencies include weak column-stronger beam formations, insufficient seismic joint separations, soft story or weak story irregularities and short columns. Similar construction and design mistakes are also observed in other countries situated on active earthquake belts. Existing buildings still have these undesirable characteristics, so to prepare for future earthquakes, they must be rehabilitated.

Description: Formation time and mean movement velocities of the 7 August Zhouqu debris flows extracted from broadband seismic records Natural Hazards and Earth System Sciences Discussions, 3, 675-695, 2015 Author(s): Z. Li, X. Huang, Q. Xu, J. Fan, D. Yu, Z. Hao, and X. Qiao The catastrophic Zhouqu debris flows, which were induced by heavy rainfall, occurred at approximately midnight of 7 August 2010 (Beijing time, UTC + 8) and claimed 1765 lives. Broadband seismic signals recorded by the Zhouqu seismic station nearby are acquired and analyzed in this paper. The seismic signals are divided into two separate parts for the first time using the crucial time of 23:33:10 (Bejing time, UTC +8), with distinctly different frequency characteristics on time-by-time normalized spectrograms and amplitude increasing patterns on smoothed envelopes. They are considered to be generated by the development stage and the maturity stage of the Sanyanyu debris flow respectively. Seismic signals corresponding to the development stage have a broader main frequency band of approximately 0–15 Hz than that of the maturity stage, which is around 1–10 Hz. The N–S component can detect the development stage of the debris flow about 3 min earlier than other components due to its southward flow direction. Two sub-stages within the maturity stage are recognized from best-fitted amplitude increasing velocities and the satellite image of the Sanyanyu flow path and the mean movement velocities of the Sanyanyu debris flow during these two sub-stages are estimated to be 9.2 and 9.7 m s −1 respectively.