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Natural Hazards and Earth System Sciences (NHESS)

Application and reliability of techniques for landslide site investigation, monitoring and early warning – outcomes from a questionnaire studyNatural Hazards and Earth System Science, 13, 3157-3168, 2013Author(s): I. Baroň and R. SupperThe presented questionnaire study summarizes an evaluation of approaches,
techniques and parameters of slope-instability investigation and monitoring
of their occurrence, reliability and the applicability of the monitoring
techniques for early warning. The study is based on information collected
from 86 monitored landslides in 14 European and Asian countries. Based on
the responses, lidar ALS (airborne laser scanners), geophysical logging, aerial photographs,
resistivity surveying, GB InSAR (ground-based synthetic aperture radar
interferometer) and the refraction seismic were considered
the most reliable methods for investigation of structure and character of
landslides. Especially lidar ALS and geophysical logging were ranked high
despite their application at relatively few landslides. Precipitation
amount, pore-water pressure and displacement monitored by wire
extensometers, dGPS and total stations, followed by air temperature and
EM-emissions monitoring and displacement monitored by the TM 71 crack gauge
were considered the most promising parameters for early warning. 2013/12/09 - 20:39

Assessment of flash floods taking into account climate change scenarios in the Llobregat River basinNatural Hazards and Earth System Science, 13, 3145-3156, 2013Author(s): M. Velasco, P. A. Versini, A. Cabello, and A. Barrera-EscodaGlobal change may imply important changes in the future occurrence and
intensity of extreme events. Climate scenarios characterizing these plausible
changes were previously obtained for the Llobregat River basin (NE Spain).
This paper presents the implementation of these scenarios in the HBV
(Hydrologiska Byråns Vattenbalansavdelning) hydrological model. Then, the
expected changes in terms of flash flood occurrence and intensity are
assessed for two different sub-basins: the Alt Llobregat and the Anoia
(Llobregat River basin).

The assessment of future flash floods has been done in terms of the
intensity and occurrence of extreme events, using a peak over threshold (POT) analysis. For these
two sub-basins, most of the simulated scenarios present an increase of the
intensity of the peak discharge values. On the other hand, the future
occurrence follows different trends in the two sub-basins: an increase is
observed in Alt Llobregat but a decrease occurs in Anoia. Despite the
uncertainties that appear in the whole process, the results obtained can
shed some light on how future flash floods events may occur. 2013/12/06 - 18:14

Calibration of a real-time tsunami detection algorithm for sites with no instrumental tsunami records: application to coastal tide-gauge stations in eastern Sicily, ItalyNatural Hazards and Earth System Science, 13, 3129-3144, 2013Author(s): L. Bressan, F. Zaniboni, and S. TintiCoastal tide gauges play a very important role in a tsunami warning system,
since sea-level data are needed for a correct evaluation of the tsunami
threat, and the tsunami arrival has to be recognized as early as possible.
Real-time tsunami detection algorithms serve this purpose. For an efficient
detection, they have to be calibrated and adapted to the specific local
characteristics of the site where they are installed, which is easily done
when the station has recorded a sufficiently large number of tsunamis. In
this case the recorded database can be used to select the best set of
parameters enhancing the discrimination power of the algorithm and minimizing
the detection time. This chance is however rare, since most of the coastal
tide-gauge stations, either historical or of new installation, have recorded
only a few tsunamis in their lifetimes, if any. In this case calibration must
be carried out by using synthetic tsunami signals, which poses the problem of
how to generate them and how to use them. This paper investigates this issue
and proposes a calibration approach by using as an example a specific case,
which is the calibration of a real-time detection algorithm called TEDA
(Tsunami Early Detection Algorithm) for two stations (namely Tremestieri and
Catania) in eastern Sicily, Italy, which were recently installed in the frame
of the Italian project TSUNET, aiming at improving the tsunami monitoring
capacity in a region that is one of the most hazardous tsunami areas of Italy
and of the Mediterranean. 2013/12/06 - 18:14

Sediment transport on the inner shelf off Khao Lak (Andaman Sea, Thailand) during the 2004 Indian Ocean tsunami and former storm events: evidence from foraminiferal transfer functionsNatural Hazards and Earth System Science, 13, 3113-3128, 2013Author(s): Y. Milker, M. Wilken, J. Schumann, D. Sakuna, P. Feldens, K. Schwarzer, and G. SchmiedlWe have investigated the benthic foraminiferal fauna from sediment event
layers associated with the 2004 Indian Ocean tsunami and former storms that
have been retrieved in short sediment cores from offshore environments of
the Andaman Sea, off Khao Lak, western Thailand. Species composition and
test preservation of the benthic foraminiferal faunas exhibit pronounced
changes across the studied sections and provide information on the
depositional history of the tsunami layer, particularly on the source water
depth of the displaced foraminiferal tests. In order to obtain accurate
bathymetric information on sediment provenance, we have mapped the
distribution of modern faunas in non-tsunamigenic surface sediments and
created a calibration data set for the development of a transfer function.
Our quantitative reconstructions revealed that the resuspension of sediment
particles by the tsunami wave was restricted to a maximum water depth of
approximately 20 m. Similar values were obtained for former storm events,
thus impeding an easy distinction of different high-energy events. 2013/12/06 - 18:14

Mapping tsunami impacts on land cover and related ecosystem service supply in Phang Nga, ThailandNatural Hazards and Earth System Science, 13, 3095-3111, 2013Author(s): G. Kaiser, B. Burkhard, H. Römer, S. Sangkaew, R. Graterol, T. Haitook, H. Sterr, and D. Sakuna-SchwartzThe 2004 Indian Ocean tsunami caused damages to coastal ecosystems and thus
affected the livelihoods of the coastal communities who depend on services
provided by these ecosystems. The paper presents a case study on evaluating
and mapping the spatial and temporal impacts of the tsunami on land use and
land cover (LULC) and related ecosystem service supply in the
Phang Nga province, Thailand. The method includes local stakeholder
interviews, field investigations, remote-sensing techniques, and GIS.
Results provide an ecosystem services matrix with capacity scores
for 18 LULC classes and 17 ecosystem functions and services as well as
pre-/post-tsunami and recovery maps indicating changes in the ecosystem
service supply capacities in the study area. Local stakeholder interviews
revealed that mangroves, casuarina forest, mixed beach forest, coral reefs, tidal inlets, as
well as wetlands (peat swamp forest) have the highest capacity to supply
ecosystem services, while e.g. plantations have a lower capacity. The
remote-sensing based damage and recovery analysis showed a loss of the
ecosystem service supply capacities in almost all LULC classes for most of
the services due to the tsunami. A fast recovery of LULC and related
ecosystem service supply capacities within one year could be observed for
e.g. beaches, while mangroves or casuarina forest needed several years to
recover. Applying multi-temporal mapping the spatial variations of
could be visualised. While some patches of coastal forest were fully
recovered after 3 yr, other patches were still affected and thus had
a reduced capacity to supply ecosystem services. The ecosystem services maps can
be used to quantify ecological values and their spatial distribution in the
framework of a tsunami risk assessment. Beyond that they are considered to
be a useful tool for spatial analysis in coastal risk management in Phang
Nga. 2013/12/06 - 18:14

Scale model for the confluent area of debris flow and main river: a case study of the Wenjia GullyNatural Hazards and Earth System Science, 13, 3083-3093, 2013Author(s): J. Zhang, Z. X. Guo, S. Y. Cao, and V. P. SinghWhen debris flow discharges into the main river, the deposition of debris
raises the river bed, occupies the path of water conveyance and damages or
even destroys buildings, resulting in considerable economic loss and
possibly fatalities. Mathematical models are normally employed to compute debris flow.
However, most of these models employ empirical formulae and coefficients and
their results are seldom reliable. On the other hand, scale model tests
associated with debris flow have seldom been conducted due to the lack of
corresponding similarity laws and the difficulty of achieving the grain
diameter scale. Focusing on pseudo-one-phase flow, this paper discusses the
laws of similarity for the confluence of debris flow and main river and
conducts a case study of the debris flow that occurred on 13 August 2010, in
the Wenjia Gully, China. After satisfying the roughness scale, the kinematic
viscosity coefficient scale, and the momentum ratio scale, it was found that
the deposition terrain in the model test is consistent with the one in the
prototype. 2013/12/02 - 14:04

Adaptability and transferability of flood loss functions in residential areasNatural Hazards and Earth System Science, 13, 3063-3081, 2013Author(s): H. Cammerer, A. H. Thieken, and J. LammelFlood loss modeling is an important component within flood risk assessments.
Traditionally, stage-damage functions are used for the estimation of direct
monetary damage to buildings. Although it is known that such functions are
governed by large uncertainties, they are commonly applied – even in
different geographical regions – without further validation, mainly due to
the lack of real damage data. Until now, little research has been done to
investigate the applicability and transferability of such damage models to
other regions. In this study, the last severe flood event in the Austrian
Lech Valley in 2005 was simulated to test the performance of various damage
functions from different geographical regions in Central Europe for the
residential sector. In addition to common stage-damage curves, new functions
were derived from empirical flood loss data collected in the aftermath of
recent flood events in neighboring Germany. Furthermore, a
multi-parameter flood loss model for the residential sector was adapted to
the study area and also evaluated with official damage data. The analysis
reveals that flood loss functions derived from related and more similar
regions perform considerably better than those from more heterogeneous
data sets of different regions and flood events. While former loss functions estimate the
observed damage well, the latter overestimate the reported loss clearly. To
illustrate the effect of model choice on the resulting uncertainty of damage
estimates, the current flood risk for residential areas was calculated. In
case of extreme events like the 300 yr flood, for example, the range of
losses to residential buildings between the highest and the lowest estimates
amounts to a factor of 18, in contrast to properly validated models with a
factor of 2.3. Even if the risk analysis is only performed for residential
areas, our results reveal evidently that a carefree model transfer in other
geographical regions might be critical. Therefore, we conclude that loss
models should at least be selected or derived from related regions with
similar flood and building characteristics, as far as no model validation is
possible. To further increase the general reliability of flood loss
assessment in the future, more loss data and more comprehensive loss data for model
development and validation are needed. 2013/11/30 - 19:36

Mapping wave set-up near a complex geometric urban coastlineNatural Hazards and Earth System Science, 13, 3049-3061, 2013Author(s): T. Soomere, K. Pindsoo, S. R. Bishop, A. Käärd, and A. ValdmannWave induced set-up is a process that leads to increased water levels in
coastal regions. When coupled with storm conditions, wave set-up – or, for
brevity, set-up – can significantly increase the risk of flooding or
structural damage and therefore is of particular importance when considering
coastal management or issues related to the planning of nearshore
infrastructures. Here, we investigate the effects of set-up in the coastal
region of the Gulf of Finland in the Baltic Sea, close to Tallinn, Estonia,
although the results will have wider relevance for many other areas. Due to
a lack of continuous wave data we employ modelling to provide input data
using a calculation scheme based on a high-resolution (470 m) spectral wave
model WAM to replicate spatial patterns of wave properties based on
high-quality, instrument-measured wind data from the neighbourhood of the
study site. The results indicate that for the specific geometry of coastline
under consideration, there is a variation in set-up which is strongly
affected by wind direction. The maximum set-up values are up to 70–80 cm in
selected locations. This is more than 50% of the all-time maximum water
level and thus may serve as a substantial source of marine hazard for
several low-lying regions around the city. Wind directions during storms
have changed in recent years and, with climate variability potentially
increasing, these results will encourage further tests which may be used
in a policy setting regarding defences or other structures in and around
coastlines. In particular, with urban development now taking place in many
coastal regions (including the one within this study) these results have
implications for local planners. They may also be incorporated into new
storm warning systems. 2013/11/30 - 19:36

Preface: Forecast and projection in climate scenario of Mediterranean intense events: uncertainties and propagation on environment (the MEDUP project)Natural Hazards and Earth System Science, 13, 3043-3047, 2013Author(s): V. Ducrocq, P. Drobinski, D. Lambert, G. Molinié, and C. Llasat 2013/11/30 - 19:36

QVAST: a new Quantum GIS plugin for estimating volcanic susceptibilityNatural Hazards and Earth System Science, 13, 3031-3042, 2013Author(s): S. Bartolini, A. Cappello, J. Martí, and C. Del NegroOne of the most important tasks of modern volcanology is the construction of
hazard maps simulating different eruptive scenarios that can be used in
risk-based decision making in land-use planning and emergency management. The
first step in the quantitative assessment of volcanic hazards is the
development of susceptibility maps (i.e., the spatial probability of a future
vent opening given the past eruptive activity of a volcano). This challenging
issue is generally tackled using probabilistic methods that use the
calculation of a kernel function at each data location to estimate
probability density functions (PDFs). The smoothness and the modeling ability
of the kernel function are controlled by the smoothing parameter, also known
as the bandwidth. Here we present a new tool, QVAST, part of the open-source
geographic information system Quantum GIS, which is designed to create
user-friendly quantitative assessments of volcanic susceptibility. QVAST
allows the selection of an appropriate method for evaluating the bandwidth for the
kernel function on the basis of the input parameters and the shapefile
geometry, and can also evaluate the PDF with the Gaussian kernel. When
different input data sets are available for the area, the total susceptibility
map is obtained by assigning different weights to each of the PDFs, which are
then combined via a weighted summation and modeled in a non-homogeneous
Poisson process. The potential of QVAST, developed in a free and
user-friendly environment, is here shown through its application in the
volcanic fields of Lanzarote (Canary Islands) and La Garrotxa (NE Spain). 2013/11/27 - 22:19

The role of risk perception in making flood risk management more effectiveNatural Hazards and Earth System Science, 13, 3013-3030, 2013Author(s): M. Buchecker, G. Salvini, G. Di Baldassarre, E. Semenzin, E. Maidl, and A. MarcominiOver the last few decades, Europe has suffered from a number of severe flood
events and, as a result, there has been a growing interest in probing
alternative approaches to managing flood risk via prevention measures. A
literature review reveals that, although in the last decades risk evaluation
has been recognized as key element of risk management, and risk assessment
methodologies (including risk analysis and evaluation) have been improved by
including social, economic, cultural, historical and political conditions,
the theoretical schemes are not yet applied in practice. One main reason for
this shortcoming is that risk perception literature is mainly of universal
and theoretical nature and cannot provide the necessary details to implement
a comprehensive risk evaluation. This paper therefore aims to explore a
procedure that allows the inclusion of stakeholders' perceptions of
prevention measures in risk assessment. It proposes to adopt methods of risk
communication (both one-way and two-way communication) in risk assessment
with the final aim of making flood risk management more effective. The
proposed procedure not only focuses on the effect of discursive risk
communication on risk perception, and on achieving a shared assessment of
the prevention alternatives, but also considers the effects of the
communication process on perceived uncertainties, accepted risk levels, and
trust in the managing institutions.

The effectiveness of this combined procedure has been studied and
illustrated using the example of the participatory flood prevention
assessment process on the Sihl River in Zurich, Switzerland. The main
findings of the case study suggest that the proposed procedure performed
well, but that it needs some adaptations for it to be applicable in
different contexts and to allow a (semi-) quantitative estimation of risk
perception to be used as an indicator of adaptive capacity. 2013/11/27 - 22:19

Corrigendum to "The UBO-TSUFD tsunami inundation model: validation and application to a tsunami case study focused on the city of Catania, Italy" published in Nat. Hazards Earth Syst. Sci., 13, 1795–1816, 2013Natural Hazards and Earth System Science, 13, 3011-3011, 2013Author(s): S. Tinti and R. ToniniNo abstract available. 2013/11/26 - 20:23

Reduction of maximum tsunami run-up due to the interaction with beachfront development – application of single sinusoidal wavesNatural Hazards and Earth System Science, 13, 2991-3010, 2013Author(s): N. GosebergExperiments are presented that focus on the interaction of single sinusoidal
long waves with beachfront development on the shore. A pump-driven
methodology is applied to generate the tested waves in the wave flume. The
approaching waves firstly propagate over a horizontal bottom, then climbing
up a 1 in 40 beach slope. The experiments reported here are confined to the
surf similarity parameter of the waves ranging from ξ =7.69–10.49. The
maximum run-up of the tested waves under undisturbed conditions agrees well
with analytical results of
of Madsen and Schäffer (2010).
Beachfront development is modelled with cubic concrete blocks
(macro-roughness (MR) elements). The obstruction ratio, the number of element
rows parallel to the shoreline as well as the way of arranging the MR
elements influences the overall reduction of maximum run-up compared to the
undisturbed run-up conditions. Staggered and aligned as well as rotated and
non-rotated arrangements are tested. As a result, nomograms are finally
compiled to depict the maximum run-up reduction over the surf similarity
parameter. In addition, some guidance on practical application of the
results to an example location is given. 2013/11/23 - 00:10

Mesoscale numerical analysis of the historical November 1982 heavy precipitation event over Andorra (Eastern Pyrenees)Natural Hazards and Earth System Science, 13, 2969-2990, 2013Author(s): L. Trapero, J. Bech, F. Duffourg, P. Esteban, and J. LorenteFrom 6 to 8 November 1982 one of the most catastrophic flash-flood
events was recorded in the Eastern Pyrenees affecting Andorra and also
France and Spain with rainfall accumulations exceeding 400 mm in 24 h, 44
fatalities and widespread damage. This paper aims to exhaustively document
this heavy precipitation event and examines mesoscale
simulations performed by the French Meso-NH non-hydrostatic atmospheric
model. Large-scale simulations show the slow-evolving synoptic environment
favourable for the development of a deep Atlantic cyclone which induced a
strong southerly flow over the Eastern Pyrenees. From the evolution of the
synoptic pattern four distinct phases have been identified during the event.
The mesoscale analysis presents the second and the third phase as the most
intense in terms of rainfall accumulations and highlights the interaction of
the moist and conditionally unstable flows with the mountains. The presence
of a SW low level jet (30 m s−1) around 1500 m also had a crucial role on
focusing the precipitation over the exposed south slopes of the Eastern Pyrenees. Backward trajectories based on Eulerian on-line passive tracers
indicate that the orographic uplift was the main forcing mechanism which
triggered and maintained the precipitating systems more than 30 h over
the Pyrenees. The moisture of the feeding flow mainly came from the Atlantic
Ocean (7–9 g kg−1) and the role of the Mediterranean as a local moisture
source was very limited (2–3 g kg−1) due to the high initial water vapour
content of the parcels and the rapid passage over the basin along the
Spanish Mediterranean coast (less than 12 h). 2013/11/23 - 00:10

Risk assessment of debris flow in Yushu seismic area in China: a perspective for the reconstructionNatural Hazards and Earth System Science, 13, 2957-2968, 2013Author(s): H. X. Lan, L. P. Li, Y. S. Zhang, X. Gao, and H. J. LiuThe 14 April 2010 Ms = 7.1 Yushu Earthquake (YE) had caused
severe damage in the Jiegu township, the residential centre of Yushu Tibetan
Autonomous Prefecture, Qinghai Province, China. In view of the fragile
geological conditions after YE, risk assessment of secondary geohazards
becomes an important concern for the reconstruction. A quantitative
methodology was developed to assess the risk of debris flow by taking into
account important intensity information. Debris flow scenarios were
simulated with respect to rainfall events with 10, 50 and 100 yr
returning period, respectively. The possible economic loss and fatalities
caused by damage to buildings were assessed both in the settlement area and
in the low hazard settlement area regarding the simulated debris flow
events. Three modelled building types were adopted, i.e. hollow brick wood
(HBW), hollow brick concrete (HBC) and reinforced concrete (RC) buildings.
The results suggest that HBC structure achieves a good balance for the
cost-benefit relationship compared with HBW and RC structures and thus could
be an optimal choice for most of the new residential buildings in the Jiegu
township. The low hazard boundary presents significant risk reduction
efficiency in the 100 yr returning debris flow event. In addition, the
societal risk for the settlement area is unacceptable when the 100 yr
returning event occurs but reduces to ALARP (as low as reasonably
practicable) level as the low hazard area is considered. Therefore, the low
hazard area was highly recommended to be taken into account in the
reconstruction. Yet, the societal risk might indeed approach an unacceptable
level if one considers that YE has inevitably increased the occurrence frequency of
debris flow. The quantitative results should be treated as a perspective for
the reconstruction rather than precise numbers of future losses, owing to the
complexity of the problem and the deficiency of data. 2013/11/23 - 00:10

Rogue waves in a wave tank: experiments and modelingNatural Hazards and Earth System Science, 13, 2951-2955, 2013Author(s): A. LechugaIn past decades theoretical studies have been carried out with the double aim
of improving knowledge of the main characteristics of the rogue wave and of
attempting to predict its sudden appearance. We have tried to generate rogue
waves in a water wave tank, using a symmetric spectrum (Akhmediev et al.,
2011a) as input on the wave maker.

The next step has been to apply a theoretical model to the amplitude envelope
of these waves. After some considerations we agreed the best model to be an
analog of the Ginzburg–Landau equation. 2013/11/20 - 15:19

Focusing wave group on a current of finite depthNatural Hazards and Earth System Science, 13, 2941-2949, 2013Author(s): D. Merkoune, J. Touboul, N. Abcha, D. Mouazé, and A. EzerskyFormation of freak waves resulting from the wave packets propagating in
finite water depth on the background of a current is studied experimentally
and numerically. In the experiment, the freak waves appear as a result of
dispersion focusing of wave train excited by wave maker with modulated
frequency. The space evolution of the frequency modulated train is studied in
numerical simulations. We showed that in the water of finite depth, a
distance of focusing increases and amplitude in the focal point decreases in
comparison with infinite water depth. Experimental results are in good
agreement with numerical simulations if wave breaking of surface waves
does not occur. 2013/11/20 - 15:19

Tsunami hazard assessment in El Salvador, Central America, from seismic sources through flooding numerical models.Natural Hazards and Earth System Science, 13, 2927-2939, 2013Author(s): J. A. Álvarez-Gómez, Í. Aniel-Quiroga, O. Q. Gutiérrez-Gutiérrez, J. Larreynaga, M. González, M. Castro, F. Gavidia, I. Aguirre-Ayerbe, P. González-Riancho, and E. CarreñoEl Salvador is the smallest and most densely populated country in Central
America; its coast has an approximate length of 320 km, 29
municipalities and more than 700 000 inhabitants. In El Salvador there were 15 recorded tsunamis between 1859 and 2012, 3 of them causing damages
and resulting in hundreds of victims. Hazard assessment is commonly based on
propagation numerical models for earthquake-generated tsunamis and can be
approached through both probabilistic and deterministic methods. A deterministic
approximation has been applied in this study as it provides essential
information for coastal planning and management. The objective of the
research was twofold: on the one hand the characterization of the threat over
the entire coast of El Salvador, and on the other the computation of flooding
maps for the three main localities of the Salvadorian coast. For the latter
we developed high-resolution flooding models. For the former, due to the
extension of the coastal area, we computed maximum elevation maps, and from
the elevation in the near shore we computed an estimation of the run-up and
the flooded area using empirical relations. We have considered local sources
located in the Middle America Trench, characterized seismotectonically, and
distant sources in the rest of Pacific Basin, using historical and recent
earthquakes and tsunamis. We used a hybrid finite differences–finite
volumes numerical model in this work, based on the linear and non-linear
shallow water equations, to simulate a total of 24 earthquake-generated
tsunami scenarios. Our results show that at the western Salvadorian coast,
run-up values higher than 5 m are common, while in the eastern area,
approximately from La Libertad to the Gulf of Fonseca, the run-up values are
lower. The more exposed areas to flooding are the lowlands in the Lempa River
delta and the Barra de Santiago Western Plains. The results of the empirical
approximation used for the whole country are similar to the results obtained
with the high-resolution numerical modelling, being a good and fast
approximation to obtain preliminary tsunami hazard estimations. In Acajutla
and La Libertad, both important tourism centres being actively developed,
flooding depths between 2 and 4 m are frequent, accompanied with high
and very high person instability hazard. Inside the Gulf of Fonseca the
impact of the waves is almost negligible. 2013/11/20 - 15:19

Analysis of human vulnerability to the extreme rainfall event on 21–22 July 2012 in Beijing, ChinaNatural Hazards and Earth System Science, 13, 2911-2926, 2013Author(s): J. Liu and S.-Y. WangThe aim of this study is to characterize the extreme rainfall event on
21–22 July 2012 in Beijing, and its impact on human vulnerability. Based on
the available meteorological and rainfall data from Beijing meteorological
stations and Surface Weather Observation Stations, the study draws hourly
rainfall maps to simulate the rainfall amount and spatial distribution. Using
these maps, this paper provides a quantitative analysis of the impact of the
temporal and spatial characteristics of rainfall on the vulnerability of
three population groups, according to age, gender and total number of
victims. The results of three linear regression models indicate the different
effects of extreme rainfall parameters on victims with different
characteristics. The analysis of victim data in this extreme rainfall event
represents the distribution and characteristics of victims in the eight
affected districts, and concludes that the "vulnerable group" are males and
adults in this extreme rainfall event. This paper is an initial effort to
analyze the impact of an extreme rainfall event on the vulnerability of
populations with different characteristics quantitatively, which can be used
by stakeholders to prioritize the extreme rainfall event impact issues, and
develop contingency plans to address and prevent the human and structural
damages caused by the extreme rainfall events. 2013/11/20 - 15:19

Influence of targeted observations on short-term forecasts of high-impact weather events in the MediterraneanNatural Hazards and Earth System Science, 13, 2891-2910, 2013Author(s): J. Campins, B. Navascués, C. Santos, and A. Amo-BaladrónThe influence of targeted observations on short-range forecasts is tested
over two different periods of PREVIEW (2008) and MEDEX (2009) data targeting
field campaigns for a set of Mediterranean high-impact weather events. As
targeted observations we have used not only extra radiosondes, but also
enhanced satellite data observed in singular vector (SV)-based sensitive
regions. Three parallel observing system experiments, based on the High-Resolution Limited-Area Model (HIRLAM) data assimilation and forecast
system, have been conducted. Forecasts of the three experiments have been
assessed using both verifying analyses for upper-air fields, and surface
observations for several meteorological parameters. Furthermore,
quantitative precipitation forecasts (QPF) have been objectively verified
using the novel feature oriented Structure–Amplitude–Location (SAL) method.

The results obtained show that extra radiosondes have an overall positive
impact on the forecasts (average improvement of all upper-air variables and
vertical levels studied is 3.6%). When in addition to extra radiosonde
data also enhanced satellite data are assimilated, the overall forecast
skill is almost doubled. However, a distinct behaviour is found between the
PREVIEW and MEDEX cases. While for MEDEX cases the improvement is slight,
for PREVIEW cases the improvement is significant (average improvements of 1.7% and
8.9%, respectively, for the experiment with enhanced satellite data). It is
suggested that this is due to the location of the target areas and the
spatial distribution of the composite observing system and to the different
atmospheric predictability in these two periods. 2013/11/20 - 15:19

Flood risk management in Italy: challenges and opportunities for the implementation of the EU Floods Directive (2007/60/EC)Natural Hazards and Earth System Science, 13, 2883-2890, 2013Author(s): J. Mysiak, F. Testella, M. Bonaiuto, G. Carrus, S. De Dominicis, U. Ganucci Cancellieri, K. Firus, and P. GrifoniItaly's recent history is punctuated with devastating flood disasters
claiming high death toll and causing vast but underestimated economic, social
and environmental damage. The responses to major flood and landslide
disasters such as the Polesine (1951), Vajont (1963), Firenze (1966),
Valtelina (1987), Piedmont (1994), Crotone (1996), Sarno (1998), Soverato
(2000), and Piedmont (2000) events have contributed to shaping the country's
flood risk governance. Insufficient resources and capacity, slow
implementation of the (at that time) novel risk prevention and protection
framework, embodied in the law 183/89 of 18 May 1989, increased the reliance
on the response and recovery operations of the civil protection. As a result,
the importance of the Civil Protection Mechanism and the relative body of
norms and regulation developed rapidly in the 1990s. In the aftermath of the
Sarno (1998) and Soverato (2000) disasters, the Department for Civil
Protection (DCP) installed a network of advanced early warning and alerting
centres, the cornerstones of Italy's preparedness for natural hazards and a
best practice worth following. However, deep convective clouds, not uncommon
in Italy, producing intense rainfall and rapidly developing localised floods
still lead to considerable damage and loss of life that can only be reduced
by stepping up the risk prevention efforts. The implementation of the EU
Floods Directive (2007/60/EC) provides an opportunity to revise the model of
flood risk governance and confront the shortcomings encountered during more
than 20 yr of organised flood risk management. This brief communication
offers joint recommendations towards this end from three projects funded by
the 2nd CRUE ERA-NET ( Funding Initiative:
FREEMAN, IMRA and URFlood. 2013/11/20 - 15:19

Preface: 11th Plinius Conference on Mediterranean StormsNatural Hazards and Earth System Science, 13, 2871-2882, 2013Author(s): M.-C. Llasat, G. Boni, R. Deidda, A. Mugnai, and J. Salat 2013/11/16 - 15:28

A wavefront orientation method for precise numerical determination of tsunami travel timeNatural Hazards and Earth System Science, 13, 2863-2870, 2013Author(s): I. V. Fine and R. E. ThomsonWe present a highly accurate and computationally efficient method (herein,
the "wavefront orientation method") for determining the travel time of
oceanic tsunamis. Based on Huygens' Principle, the method uses an eight-point
grid-point pattern and the most recent information on the orientation of the
advancing wavefront to determine the time for a tsunami to travel to a
specific oceanic location. The method is shown to provide improved accuracy
and reduced anisotropy compared with the conventional multiple grid-point
method presently in widespread use. 2013/11/16 - 15:28

Pre-, co-, and post- rockslide analysis with ALOS/PALSAR imagery: a case study of the Jiweishan rockslide, ChinaNatural Hazards and Earth System Science, 13, 2851-2861, 2013Author(s): C. Zhao, Q. Zhang, Y. Yin, Z. Lu, C. Yang, W. Zhu, and B. LiOn 5 June 2009, a catastrophic rockslide debris flow occurred at the crest
of the Jiweishan range, Chongqing Municipality, China, killing 74 people and
injuring an additional eight. We use L-band ALOS/PALSAR imagery to address
landslide processes before, during and after the slide. We employ three
different SAR methods, i.e., short baseline subsets (SBAS) interferometric
SAR (InSAR), SAR backscattering intensity change, and InSAR stacking
algorithm, to study any ground deformation before the rockslide, investigate
the affected area, and calculate the topographic change by this slide,
respectively. First, continuous deformation has been observed based on the
available ALOS/PALSAR InSAR imagery during June and December 2007. Second,
the area affected by the landslide can be inferred based on changes in SAR
backscattering intensity as well as surface topography, with an estimated
area of 0.47 million m2. Last, an InSAR-derived post-slide digital
elevation model has allowed us to estimate surface height changes due to the
slide, reaching about −80 m at the source region and about 60 m in the
deposit region, respectively. Our InSAR-derived estimates have been
validated using in situ data and 3-D lidar measurements. 2013/11/15 - 14:07

Landslide and debris flow susceptibility zonation using TRIGRS for the 2011 Seoul landslide eventNatural Hazards and Earth System Science, 13, 2833-2849, 2013Author(s): D. W. Park, N. V. Nikhil, and S. R. LeeThis paper presents the results from the application of a regional,
physically based stability model: Transient Rainfall Infiltration and
Grid-based Regional Slope-stability analysis (TRIGRS) for a region on
Woomyeon Mountain, Seoul, South Korea. This model couples an infinite-slope
stability analysis with a one-dimensional analytical solution to predict the
transient pore pressure response to the infiltration of rainfall. TRIGRS
also adopts the geographic information system (GIS) framework for
determining the whole behaviour of a slope. In this paper, we suggest an
index for evaluating the results produced by the model. Particular attention
is devoted to the prediction of routes of debris flow, using a runoff

In this context, the paper compares observed landslide and debris flow
events with those predicted by the TRIGRS model. The TRIGRS model,
originally developed to predict shallow landslides, has been extended in
this study for application to debris flows. The results predicted by the
TRIGRS model are presented as safety factor (FS) maps corresponding to
transient rainfall events, and in terms of debris flow paths using methods
proposed by several researchers in hydrology.

In order to quantify the effectiveness of the model, we proposed an index
called LRclass (landslide ratio for each predicted FS class). The
LRclass index is mainly applied in regions where the
landslide scar area is not well defined (or is unknown), in order to avoid
overestimation of the model results. The use of the TRIGRS routing module
was proposed to predict the paths of debris flow, especially in areas where
the rheological properties and erosion rates of the materials are difficult
to obtain. Although an improvement in accuracy is needed, this module is
very useful for preliminary spatio-temporal assessment over wide areas. In
summary, the TRIGRS model is a powerful tool of use to decision makers for
susceptibility mapping, particularly when linked with various advanced
applications using GIS spatial functions. 2013/11/15 - 14:07

Landslide susceptibility estimation by random forests technique: sensitivity and scaling issuesNatural Hazards and Earth System Science, 13, 2815-2831, 2013Author(s): F. Catani, D. Lagomarsino, S. Segoni, and V. TofaniDespite the large number of recent advances and developments in landslide
susceptibility mapping (LSM) there is still a lack of studies focusing on
specific aspects of LSM model sensitivity. For example, the influence of
factors such as the survey scale of the landslide conditioning variables
(LCVs), the resolution of the mapping unit (MUR) and the optimal number and
ranking of LCVs have never been investigated analytically, especially on
large data sets.

In this paper we attempt this experimentation concentrating on the impact of
model tuning choice on the final result, rather than on the comparison of
methodologies. To this end, we adopt a simple implementation of the random
forest (RF), a machine learning technique, to produce an ensemble of
landslide susceptibility maps for a set of different model settings, input
data types and scales. Random forest is a combination of Bayesian trees that
relates a set of predictors to the actual landslide occurrence. Being it a
nonparametric model, it is possible to incorporate a range of numerical or
categorical data layers and there is no need to select unimodal training
data as for example in linear discriminant analysis. Many widely
acknowledged landslide predisposing factors are taken into account as mainly
related to the lithology, the land use, the geomorphology, the structural
and anthropogenic constraints. In addition, for each factor we also include
in the predictors set a measure of the standard deviation (for numerical
variables) or the variety (for categorical ones) over the map unit.

As in other systems, the use of RF enables one to estimate the relative
importance of the single input parameters and to select the optimal
configuration of the classification model. The model is initially applied
using the complete set of input variables, then an iterative process is
implemented and progressively smaller subsets of the parameter space are
considered. The impact of scale and accuracy of input variables, as well as
the effect of the random component of the RF model on the susceptibility
results, are also examined. The model is tested in the Arno River basin
(central Italy). We find that the dimension of parameter space, the mapping
unit (scale) and the training process strongly influence the classification
accuracy and the prediction process.

This, in turn, implies that a careful sensitivity analysis making use of
traditional and new tools should always be performed before producing final
susceptibility maps at all levels and scales. 2013/11/14 - 09:32

Wind-wave amplification mechanisms: possible models for steep wave events in finite depthNatural Hazards and Earth System Science, 13, 2805-2813, 2013Author(s): P. Montalvo, R. Kraenkel, M. A. Manna, and C. KharifWe extend the Miles mechanism of wind-wave generation to finite
depth. A β-Miles linear growth rate depending on the depth
and wind velocity is derived and allows the study of linear growth
rates of surface waves from weak to moderate winds in finite depth
h. The evolution of β is plotted, for several values of the
dispersion parameter kh with k the wave number. For
constant depths we find that no matter what the values of wind
velocities are, at small enough wave age the β-Miles linear
growth rates are in the known deep-water limit. However winds of
moderate intensities prevent the waves from growing beyond
a critical wave age, which is also constrained by the water depth
and is less than the wave age limit of deep water. Depending on
wave age and wind velocity, the Jeffreys and Miles mechanisms are
compared to determine which of them dominates. A wind-forced
nonlinear Schrödinger equation is derived and the Akhmediev,
Peregrine and Kuznetsov–Ma breather solutions for weak wind inputs
in finite depth h are obtained. 2013/11/08 - 13:42

Cold fronts in the Colombian Caribbean Sea and their relationship to extreme wave eventsNatural Hazards and Earth System Science, 13, 2797-2804, 2013Author(s): J. C. Ortiz-Royero, L. J. Otero, J. C. Restrepo, J. Ruiz, and M. CadenaExtreme ocean waves in the Caribbean Sea are commonly related to the effects
of storms and hurricanes during the months of June through November. The
collapse of 200 m of the Puerto Colombia pier in March 2009 revealed the
effects of meteorological phenomena other than storms and hurricanes that may
be influencing the extreme wave regime in the Colombian Caribbean. The marked
seasonality of these atmospheric fronts was established by analyzing the
meteorological–marine reports of the Instituto de Hidrología,
Meteorología y Estudios Ambientales of Colombia (IDEAM, based on its
initials in Spanish) and the Centro de Investigación en Oceanografía
y Meteorología of Colombia (CIOH, based on its initials in Spanish)
during the last 16 yr. The highest number of cold fronts was observed during
the months of January, February, and March, with 6 fronts occurring per year.
An annual trend was observed and the highest number of fronts occurred in
2010 (20 in total); moreover, an annual strong relationship between the
maximum average wave values and the cold fronts in the central zone of the
Colombian Caribbean during the first three months of the year was
established. In addition, the maximum values of the significant height
produced by the passage of cold fronts during the last 16 yr were

Although the Colombian Caribbean has been affected by storms and hurricanes
in the past, this research allows us to conclude that there is a strong
relationship between cold fronts and the largest waves in the Colombian
Caribbean during the last 16 yr, which have caused damage to coastal
infrastructure. We verified that the passage of a cold front corresponded to
the most significant extreme wave event of the last two decades in the
Colombian Caribbean, which caused the structural collapse of the Puerto
Colombia pier, located near the city of Barranquilla, between 5 and
10 March 2009. This information is invaluable when evaluating average and
extreme wave regimes for the purpose of informing the design of structures in
this region of the Caribbean. 2013/11/08 - 13:42

Regional-scale analysis of high-mountain multi-hazard and risk indicators in the Pamir (Tajikistan) with GRASS GISNatural Hazards and Earth System Science, 13, 2779-2796, 2013Author(s): F. E. Gruber and M. MergiliWe present a model framework for the regional-scale analysis of high-mountain
multi-hazard and -risk indicators, implemented with the open-source software
package GRASS GIS. This framework is applied to a 98 300 km2 study
area centred in the Pamir (Tajikistan). It includes (i) rock slides, (ii) ice
avalanches, (iii) periglacial debris flows and (iv) lake outburst floods.
First, a hazard indicator is assigned to each relevant object (steep rock
face, glacier or periglacial slope, lake). This indicator depends on the
susceptibility and on the possible event magnitude. Second, the possible
travel distances, impact areas and, consequently, impact hazard indicators
for all types of processes are computed using empirical relationships. The
impact hazard indicators are finally superimposed with an exposure indicator
derived from the type of land use, resulting in a raster map of risk
indicators finally discretized at the community level. The analysis results
are presented and discussed at different spatial scales. The major outcome of
the study, a set of comprehensive regional-scale hazard and risk indication
maps, shall represent an objective basis for the prioritization of target
communities for further research and risk mitigation measures. 2013/11/08 - 13:42

Dynamic risk simulation to assess natural hazards risk along roadsNatural Hazards and Earth System Science, 13, 2763-2777, 2013Author(s): J. Voumard, O. Caspar, M.-H. Derron, and M. JaboyedoffRisk generated by natural hazards on roads is usually calculated with
equations integrating various parameters related to hazard and traffic.
These are static variables, like an average number of vehicles crossing this
section every day and an average vehicle speed. This methodology cannot take
into account dynamic variations of traffic and interactions between vehicles
such as speed modifications due to windy roads, slowdowns resulting from
saturated traffic or vehicle tailbacks forming in front of traffic lights.

Here we show, by means of a dynamic traffic simulator, that traffic
variations may greatly influence the risk estimation over time. The risk is
analysed on several sections of an Alpine road in Switzerland using a
dynamic vehicles approach, and compared with the results of the static
methodology. It demonstrates that risk can significantly increase on sinuous
sections because of decreasing vehicle speed. For example, along an 800 m-long section of road containing two hairpin bends, the dynamic risk is about
50% higher than the static one. Badly placed signalization, slowing down,
or stopping the vehicles in a hazardous area may increase the risk by about
150% (i.e. 2.5 times higher) along a straight road section where vehicles
speed is high.

A more realistic risk can thus be obtained from a dynamic approach,
especially on mountain roads. The dynamic traffic simulator developed for
this work appears to be a helpful tool to support decision-making in
reducing risk on mountain roads and it shows the importance of keeping the
traffic moving as freely as possible. 2013/11/06 - 20:06

Using volunteered geographical information to map the November 2012 floods in SloveniaNatural Hazards and Earth System Science, 13, 2753-2762, 2013Author(s): M. Triglav-Čekada and D. RadovanVolunteered geographical information represents a promising field in the
monitoring and mapping of natural disasters. The contributors of volunteered
geographical information have the advantage that they are at the location of
the natural disaster at exactly the time when the disaster happened.
Therefore, they can provide the most complete account of the extent of the
damage. This is not always possible when applying photogrammetric or
remote-sensing methods, as prior to the data acquisition an order to carry
out the measurements has to be made. On 5 and 6 November 2012 almost half of
Slovenia was badly affected by floods. The gathering of volunteered
geographical information in the form of images and videos of these floods is
presented. Two strategies were used: (1) a public call for volunteered
contributions and (2) a web search for useful images and their authors. The
authorship of these images was verified with every contributor. In total, 15
contributors provided 102 terrestrial and aerial images and one aerial video,
with 45% classified as potentially useful. For actual flood mapping 22
images and 12 sequences from video were used. With the help of the
volunteered images 12% of the most severely affected river sections were
mapped. Altogether, 1195.3 ha of flooded areas outside of the usual
river beds along a total river length of 48 km were mapped. The
results are compared with those from satellite mapping of the same floods,
which successfully covered 18% of the most affected river sections. 2013/11/06 - 20:06

Resonance phenomena at the long wave run-up on the coastNatural Hazards and Earth System Science, 13, 2745-2752, 2013Author(s): A. Ezersky, D. Tiguercha, and E. PelinovskyRun-up of long waves on a beach consisting of three pieces of constant but
different slopes is studied. Linear shallow-water theory is used for incoming
impulse evolution, and nonlinear corrections are obtained for the run-up
stage. It is demonstrated that bottom profile influences the run-up
characteristics and can lead to resonance effects: increase of wave height,
particle velocity, and number of oscillations. Simple parameterization of
tsunami source through an earthquake magnitude is used to calculate the
run-up height versus earthquake magnitude. It is shown that resonance effects
lead to the sufficient increase of run-up heights for the weakest
earthquakes, and a tsunami wave does not break on chosen bottom relief if the
earthquake magnitude does not exceed 7.8. 2013/11/06 - 20:06

Temporary seismic monitoring of the Sulmona area (Abruzzo, Italy): a quality study of microearthquake locationsNatural Hazards and Earth System Science, 13, 2727-2744, 2013Author(s): M. A. Romano, R. de Nardis, M. Garbin, L. Peruzza, E. Priolo, G. Lavecchia, and M. RomanelliThanks to the installation of a temporary seismic network, a microseismicity
study has been conducted in the Sulmona area (Abruzzo, Italy) with the aim
of increasing the knowledge of seismogenic potential of existing active
faults. In this work the first 7 months (from 27 May to 31 December
2009) of recorded data have been analysed over a total period of
acquisition of about 30 months. Using a semi-automatic procedure, more than
800 local earthquakes have been detected, which highlights the previously unknown background
seismicity. About 70% of these events have been
relocated using a 1-D velocity model estimated specifically for the Sulmona
area. The integration of temporary network data with all the other data
available in the region enables us to obtain a statistically more robust
data set of earthquake locations. Both the final hypocentral solutions and
phase pickings are released as a supplement; an appendix also
describes phase readings' quality with respect to weighting schemes used by
location algorithms. Local magnitude values of the newly detected
events range between −1.5 and 3.7 and the completeness magnitude for the
Sulmona area during the study period is about 1.1. Duration magnitude
coefficients have been estimated as well for comparison/integration
purposes. The local Gutenberg–Richter relationship, estimated from the
microseismic data, features a low b value, tentatively suggesting that the
Sulmona area may be currently undergoing high-stress conditions, in
agreement with other recent studies. The time–space distribution of the
seismic activity with respect to the known active faults as well the
seismogenic layer thickness are preliminarily investigated. 2013/11/06 - 20:06

The role of GIS in urban seismic risk studies: application to the city of Almería (southern Spain)Natural Hazards and Earth System Science, 13, 2717-2725, 2013Author(s): A. Rivas-Medina, J. M. Gaspar-Escribano, B. Benito, and M. A. BernabéThis work describes the structure and characteristics of the geographic
information system (GIS) developed for the urban seismic risk study of the
city of Almería (southern Spain), identifying the stages in which the
use of this tool proved to be very beneficial for adopting informed decisions
throughout the execution of the work.

After the completion of the regional emergency plans for seismic risk in
Spain and its subsequent approval by the National Civil Defence Commission,
the municipalities that need to develop specific local seismic risk plans
have been identified. Hence, the next action is to develop urban seismic
risk analyses at a proper scale (Urban Seismic Risk Evaluation – Risk-UR).

For this evaluation, different factors influencing seismic risk such as
seismic hazard, geotechnical soil characteristics, vulnerability of
structures of the region, reparation costs of damaged buildings and exposed
population are combined. All these variables are gathered and analysed
within a GIS and subsequently used for seismic risk estimation. The GIS
constitutes a highly useful working tool because it facilitates data
interoperability, making the great volume of information required and the
numerous processes that take part in the calculations easier to handle,
speeding up the analysis and the interpretation and presentation of the
results of the different working phases.

The result of this study is based on a great set of variables that provide a
comprehensive view of the urban seismic risk, such as the damage
distribution of buildings and dwellings of different typologies, the mean
damage and the number of uninhabitable buildings for the expected seismic
motion, the number of dead and injured at different times of the day, the
cost of reconstruction and repair of buildings, among others. These results
are intended for interpretation and decision making in emergency management
by unspecialised users (Civil Defence technicians and managers). 2013/11/06 - 20:06

Resilience and disaster risk reduction: an etymological journeyNatural Hazards and Earth System Science, 13, 2707-2716, 2013Author(s): D. E. AlexanderThis paper examines the development over historical time of the meaning and
uses of the term resilience. The objective is to deepen our understanding of
how the term came to be adopted in disaster risk reduction and resolve some
of the conflicts and controversies that have arisen when it has been used.
The paper traces the development of resilience through the sciences,
humanities, and legal and political spheres. It considers how mechanics
passed the word to ecology and psychology, and how from there it was adopted
by social research and sustainability science. As other authors have noted,
as a concept, resilience involves some potentially serious conflicts or
contradictions, for example between stability and dynamism, or between
dynamic equilibrium (homeostasis) and evolution. Moreover, although the
resilience concept works quite well within the confines of general systems
theory, in situations in which a systems formulation inhibits rather than
fosters explanation, a different interpretation of the term is warranted.
This may be the case for disaster risk reduction, which involves
transformation rather than preservation of the "state of the system". The
article concludes that the modern conception of resilience derives benefit
from a rich history of meanings and applications, but that it is
dangerous – or at least potentially disappointing – to read to much into the
term as a model and a paradigm. 2013/11/06 - 20:06

Definition and impact of a quality index for radar-based reference measurements in the H-SAF precipitation product validationNatural Hazards and Earth System Science, 13, 2695-2705, 2013Author(s): A. Rinollo, G. Vulpiani, S. Puca, P. Pagliara, J. Kaňák, E. Lábó, L'. Okon, E. Roulin, P. Baguis, E. Cattani, S. Laviola, and V. LevizzaniThe EUMETSAT Satellite Application Facility on Support to Operational
Hydrology and Water Management (H-SAF) provides rainfall estimations based
on infrared and microwave satellite sensors on board polar and geostationary
satellites. The validation of these satellite estimations is performed
by the H-SAF Precipitation Product Validation Group (PPVG). A common validation
methodology has been defined inside the PPVG in order to make validation
results from several institutes comparable and understandable.

The validation of the PR-OBS-3 (blended infrared–microwave (IR–MW) instantaneous rainfall
estimation) product using radar-based rainfall estimations as ground
reference is described herein. A network of C-band and Ka-band radars
throughout Europe ensures a wide area coverage with different orographic
configurations and climatological regimes, but the definition of a quality
control protocol for obtaining consistent ground precipitation fields across
several countries is required.

Among the hydro-meteorological community, the evaluation of the data quality
is a quite consolidated practice, even though a unique definition of a
common evaluation methodology between different countries and institutions
has not been set up yet.

Inside H-SAF, the first definition of the quality index of the radar
rainfall observations has been introduced at the Italian Civil Protection Department (DPC). In the evaluation of the DPC quality index, several
parameters are considered, some measured by the radar itself (static clutter
map, range distance, radial velocity, texture of differential reflectivity,
texture of co-polar correlation coefficient and texture of differential
phase shift) and some obtained by external sources (digital elevation model,
freezing layer height). In some cases, corrections were applied for clutter
and beam blocking.

The DPC quality index was calculated and applied to some relevant
meteorological events reported by a radar test site in Italy. The
precipitation field derived by radar data was compared with the PR-OBS-3
precipitation product, with varying thresholds of quality index: the impact
of the introduction of the quality index defined on the statistical results
of the satellite product validation as well as their sensitivity to the threshold
choice were thus evaluated. Results show that PR-RMSE (a relative RMSE here
introduced) is reduced from values between 2.5 and 3 to values around 1 when
the quality threshold is increased from 0 (no threshold) to 0.8. Fractional
standard error also decreases, from values around 2 to values around 1.5 in
the same span of the quality threshold. 2013/10/28 - 15:16

Direct and indirect economic impacts of drought in the agri-food sector in the Ebro River basin (Spain)Natural Hazards and Earth System Science, 13, 2679-2694, 2013Author(s): M. Gil, A. Garrido, and N. Hernández-MoraThe economic evaluation of drought impacts is essential in order to define
efficient and sustainable management and mitigation strategies. The aim of
this study is to evaluate the economic impacts of a drought event on the
agricultural sector and measure how they are transmitted from primary
production to industrial output and related employment. We fit econometric
models to determine the magnitude of the economic loss attributable to water
storage. The direct impacts of drought on agricultural productivity are
measured through a direct attribution model. Indirect impacts on agricultural
employment and the agri-food industry are evaluated through a nested indirect
attribution model. The transmission of water scarcity effects from
agricultural production to macroeconomic variables is measured through
chained elasticities. The models allow for differentiating the impacts
deriving from water scarcity from other sources of economic losses. Results
show that the importance of drought impacts are less relevant at the
macroeconomic level, but are more significant for those activities directly
dependent on water abstractions and precipitation. From a management
perspective, implications of these findings are important to develop
effective mitigation strategies to reduce drought risk exposure. 2013/10/28 - 15:16

Preface "Natural hazard resilient cities"Natural Hazards and Earth System Science, 13, 2675-2678, 2013Author(s): D. Serre and B. Barroca 2013/10/24 - 20:19

Experiences from site-specific landslide early warning systemsNatural Hazards and Earth System Science, 13, 2659-2673, 2013Author(s): C. Michoud, S. Bazin, L. H. Blikra, M.-H. Derron, and M. JaboyedoffLandslide early warning systems (EWSs) have to be implemented in areas with
large risk for populations or infrastructures when classical structural
remediation measures cannot be set up. This paper aims to gather experiences
of existing landslide EWSs, with a special focus on practical requirements
(e.g., alarm threshold values have to take into account the smallest detectable
signal levels of deployed sensors before being established) and specific
issues when dealing with system implementations. Within the framework of the
SafeLand European project, a questionnaire was sent to about one-hundred
institutions in charge of landslide management. Finally, we interpreted
answers from experts belonging to 14 operational units related to 23
monitored landslides. Although no standard requirements exist for designing
and operating EWSs, this review highlights some key elements, such as the
importance of pre-investigation work, the redundancy and robustness of
monitoring systems, the establishment of different scenarios adapted to
gradual increasing of alert levels, and the necessity of confidence and
trust between local populations and scientists. Moreover, it also confirms
the need to improve our capabilities for failure forecasting, monitoring
techniques and integration of water processes into landslide conceptual
models. 2013/10/23 - 17:30

A first-order second-moment calculation for seismic hazard assessment with the consideration of uncertain magnitude conversionNatural Hazards and Earth System Science, 13, 2649-2657, 2013Author(s): J. P. Wang, X. Yun, and Y.-M. WuEarthquake size can be described with different magnitudes
for different purposes. For example, local magnitude ML is usually
adopted to compile an earthquake catalog, and moment magnitude Mw is
often prescribed by a ground motion model. Understandably, when inconsistent
units are encountered in an earthquake analysis, magnitude conversion needs
to be performed beforehand. However, the conversion is not expected at full
certainty owing to the model error of empirical relationships. This paper
introduces a novel first-order second-moment (FOSM) calculation to estimate
the annual rate of earthquake motion (or seismic hazard) on a probabilistic
basis, including the consideration of the uncertain magnitude conversion and
three other sources of earthquake uncertainties. In addition to the
methodology, this novel FOSM application to engineering seismology is
demonstrated in this paper with a case study. With a local ground motion
model, magnitude conversion relationship and earthquake catalog, the
analysis shows that the best-estimate annual rate of peak ground acceleration (PGA) greater than
0.18 g
(induced by earthquakes) is 0.002 per year at a site in Taipei, given the
uncertainties of magnitude conversion, earthquake size, earthquake location,
and motion attenuation. 2013/10/23 - 17:30