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Natural Hazards

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ISSN (Print) 1573-0840 - ISSN (Online) 0921-030X
Published by Springer-Verlag

[2216 journals]

US billion-dollar weather and climate disasters: data sources, trends, accuracy and biases
- Abstract: Abstract This paper focuses on the US Billion-dollar Weather/Climate Disaster report by the National Oceanic and Atmospheric Administration’s National Climatic Data Center. The current methodology for the production of this loss dataset is described, highlighting its strengths and limitations including sources of uncertainty and bias. The Insurance Services Office/Property Claims Service, the US Federal Emergency Management Agency’s National Flood Insurance Program and the US Department of Agriculture’s crop insurance program are key sources of quantified disaster loss data, among others. The methodology uses a factor approach to convert from insured losses to total direct losses, one potential limitation. An increasing trend in annual aggregate losses is shown to be primarily attributable to a statistically significant increasing trend of about 5 % per year in the frequency of billion-dollar disasters. So the question arises of how such trend estimates are affected by uncertainties and biases in the billion-dollar disaster data. The net effect of all biases appears to be an underestimation of average loss. In particular, it is shown that the factor approach can result in a considerable underestimation of average loss of roughly 10–15 %. Because this bias is systematic, any trends in losses from tropical cyclones appear to be robust to variations in insurance participation rates. Any attribution of the marked increasing trends in crop losses is complicated by a major expansion of the federally subsidized crop insurance program, as a consequence encompassing more marginal land. Recommendations concerning how the current methodology can be improved to increase the quality of the billion-dollar disaster dataset include refining the factor approach to more realistically take into account spatial and temporal variations in insurance participation rates.
  PubDate: 2013-06-01
The role of soil surface water regimes and raindrop impact on hillslope soil erosion and nutrient losses
- Abstract: Abstract Few investigations have addressed the interaction between soil surface water regimes and raindrop impact on nutrient losses, especially under artesian seepage condition. A simulation study was conducted to examine the effects on nitrogen and phosphorus losses. Four soil surface water regimes were designed: free drainage, saturation with rainfall, artesian seepage without rainfall, and artesian seepage with rainfall. These water regimes were subjected to two surface treatments: with and without raindrop impact through placing nylon net over soil pan. The results showed saturation and seepage with rainfall conditions induced greater soil loss and nutrient losses than free drainage condition. Nutrient concentrations in runoff from artesian seepage without rainfall condition were 7.3–228.7 times those from free drainage condition. Nutrient losses by runoff from saturation and seepage with rainfall conditions increased by factors of 1.30–9.38 and 2.81–40.11 times, and the corresponding losses with eroded sediment by 1.37–7.67 and 1.75–9.0 times, respectively, relative to those from free drainage condition. Regardless of different soil surface water regimes, raindrop impact increased 20.90–94.0 % nutrient losses with eroded sediment by promoting soil loss, but it only significantly enhanced nutrient transport to runoff under free drainage condition.
  PubDate: 2013-06-01
Assessment of physical vulnerability to agricultural drought in China
- Abstract: Abstract Food security has drawn great attention from both researchers and practitioners in recent years. Global warming and its resultant extreme drought events have become a great challenge to crop production and food price stability. This study aimed to establish a preliminary theoretical methodology and an operational approach for assessing the physical vulnerability of two wheat varieties (“Yongliang #4” and “Wenmai #6”) to agricultural drought using Environmental Policy Integrated Climate model (EPIC). Drought hazard index was set up based on output variables of the EPIC water stress (WS), including the magnitude and duration of WS during the crop-growing period. The physical vulnerability curves of two wheat varieties to drought were calculated by the simulated drought hazard indexes and loss ratios. And the curve’s effect on drought disaster risk was defined as A, B and C sections, respectively. Our analysis results showed that (a) physical vulnerability curves varied between two wheat varieties, which were determined by genetic parameters of crops; (b) compared with spring wheat “Yongliang 4#” winter wheat “Wenmai 6#” was less vulnerable to drought under the same drought hazard intensity scenario; (c) the wheat physical vulnerability curve to drought hazard displayed a S shape, suggesting a drought intensity–dependent magnifying or reducing effect of the physical vulnerability on drought disasters; (d) the reducing effect was mainly in the low-value area of vulnerability curve, whereas the magnifying effect was in the middle-value area, and the farming-pastoral zone and the Qinling Mountain–Huaihe River zone formed important spatial division belts.
  PubDate: 2013-06-01
Beijing storm of July 21, 2012: observations and reflections
- PubDate: 2013-06-01
A comparative analysis of interface erosion tests
- Abstract: Abstract Interface erosion is one of the main phenomena in dams, dikes and their foundations which may increase their failure risk. In laboratories, the jet erosion test (JET) and the hole erosion test (HET) are commonly used for the evaluation of the sensibility of interface erosion of fine soils. The results are interpreted by two distinct methods that are valid for one test only. A new energy analysis of the tests is developed, relating the total eroded mass to the dissipated fluid energy, and a new erosion resistance index is proposed. Seven naturally occurring fine-grained soils, covering a large range of erodibility, are compacted with the Proctor protocol, and they are tested with the two devices. It was shown that by using the commonly used methods, the values of the erosion coefficient are systematically higher with the JET than with the HET and the HET critical shear stress is about fifty times higher than the JET critical shear stress. Thus, the relative soil classifications yielded by the two erodimeters are not exactly the same. Based on energy analysis, values of erosion resistance index are roughly the same for each tested soil with the two apparatuses and a single classification of soil erodibility is obtained.
  PubDate: 2013-06-01
Spatial distribution of the extreme hydrological events in Xinjiang, north-west of China
- Abstract: Abstract We examined spatial distribution characteristics of extreme hydrological events in Xinjiang, China, using district data from 1901 to 2010. Frequency distribution showed a general symmetry along the Tianshan Mountains, with even distribution in Junggar Basin and Tarim Basin. Frequency was more in the north-west than in the south-east. The maximum incidence was in west Tianshan Mountains and generally decreased south-eastward. There were significant regional variations in type distribution. Rainstorm floods were more common in central Xinjiang. Hailstorms mainly occurred in the central Junggar Basin, the southern slope of the western Tianshan Mountains and north-west of Tarim Basin. Debris flow was mainly distributed in Ili Valley and the central northern Tianshan Mountains. Glacier lake outburst floods were more common in the Karakorum Mountains and southern slopes of the western Tianshan Mountains. Ice floods were mainly distributed in the western Tianshan Mountains. Snow hazards were mainly distributed in the wide northern areas, especially the Altai Mountains and Hamilton Basin. Snowmelt floods were mainly distributed in the Tacheng Basin and Ili Valley. The incidence of extreme hydrological events was greatly affected by weather systems and terrain features.
  PubDate: 2013-06-01
A new model for calculating the design wave height in typhoon-affected sea areas
- Abstract: Abstract High precision design wave height is required in extreme marine environments in typhoon-affected sea areas. A new model is built under typhoon effect to calculate the design wave heights. The new model has multiple undetermined parameters, and it is able to fit observed data more flexibly and accurately. In addition, the distribution functions of this new model are based on the maximum entropy principle. Therefore, they can avoid the apriority, which means arbitrarily assigning Poisson distribution to describe the distribution of typhoon occurrence frequency and assigning Gumbel distribution or Pearson-III distribution to describe the distribution of extreme events in the process of applying the compound distribution to deduce the design elevations. The observed data of 18-year (1984–2001) extreme wave heights and the corresponding typhoon events in Maidao are used to test the model. Test results show that the new model is theoretically more stable and more precise when predicting the design wave heights under the typhoon-affected sea areas.
  PubDate: 2013-06-01
Urbanization process and induced environmental geological hazards in China
- Abstract: Abstract Urbanization is a common development trend of countries all over the world, which is a mark of civilization and progress of human beings. The number of urbanization-induced environmental geological hazards has grown steadily in recent years and is receiving increased attention throughout the world. The purpose of this paper is to generalize China’s urbanization process and induced environmental geological hazards. Driving forces and characteristics of urbanization are briefly introduced in this study; specifically, the distribution of urban agglomerations is principally related to water resources, transportation and energy. Common geological hazards and particular ones in mountain city, mining city and coastal city are also summarized. The type and severity of hazards are different due to the differences of natural conditions and various urban functions. Main environmental geological hazards in cities are land subsidence, landslide and seawater intrusion, etc. Accordingly, reasons for these urbanization-induced geological hazards in different type of cities are analyzed and discussed. The research results may provide a clear perspective for urban geological hazard prevention, and suggestions for urban geological hazard control are pointed out.
  PubDate: 2013-06-01
Debris flow prediction models based on environmental factors and susceptible subarea classification in Sichuan, China
- Abstract: Abstract Environmental factors account for the occurrence of debris flow, as well as different weights of subareas with different risk levels. Considering the relationship between debris flow and rainfall (including the intraday rainfall and the effective rainfall of the previous 10 days), seven environmental factors, including elevation, slope, aspect, flow accumulation, vegetation coverage, soil, and land use, were added in this study. The whole area of Sichuan Province was divided into subareas according to different risk levels. Debris flow prediction models were then established by using a logistic regression model. Results showed that the prediction accuracy was decreased approximately by 3 % after the environmental factors were introduced to the entire study area. The prediction accuracy of the prediction models that comprised the introduced environmental factors was increased by 22.2, 9.7, and 14.3 % in different susceptible areas (moderately susceptible, highly susceptible, very highly susceptible), respectively, compared with that of the prediction models in which rainfall was only considered. Therefore, the research method that introduced the environmental factors may be used to improve the accuracy of debris flow prediction models based on susceptible area classification.
  PubDate: 2013-06-01
Use of remote sensing-derived variables in developing a forest fire danger forecasting system
- Abstract: Abstract Our aim was to develop a remote sensing-based forest fire danger forecasting system (FFDFS) and its implementation in forecasting 2011 fire season in the Canadian province of Alberta. The FFDFS used Moderate Resolution Imaging Spectroradiometer (MODIS)-derived 8-day composites of surface temperature, normalized multiband drought index, and normalized difference vegetation index as input variables. In order to eliminate the data gaps in the input variables, we propose a gap-filling technique by considering both of the spatial and temporal dimensions. These input variables were calculated during the i period and then integrated to forecast the fire danger conditions into four categories (i.e., very high, high, moderate, and low) during the i + 1 period. It was observed that 98.19 % of the fire fell under “very high” to “moderate” danger classes. The performance of this system was also demonstrated its ability to forecast the worst fires occurred in Slave Lake and Fort McMurray region during mid-May 2011. For example, 100 and 94.0 % of the fire spots fell under “very high” to “high” danger categories for Slave Lake and Fort McMurray regions, respectively.
  PubDate: 2013-06-01
Evaluation of allowable withdrawn volume of groundwater based on observed data
- Abstract: Abstract To control land subsidence due to groundwater withdrawal, it is important to estimate allowable withdrawn volume of groundwater in a soft deposit. This technical note presents a simple approach for estimating the allowable withdrawn volume of a deposit. A regression analysis method was used based on measured land subsidence and recorded net withdrawn volume. This approach was proposed based on the principle of soil compression at different effective stresses, i.e. the soil compression is small when the consolidation stress is lower than the yield stress of the deposit, but large when the consolidation stress is higher than the yield stress. Two case studies are presented in this technical paper to demonstrate how to use the simple approach to estimate the allowable withdrawn volume.
  PubDate: 2013-06-01
Comparison of debris-flow volume and activity under different formation conditions
- Abstract: Abstract Debris flows frequently occurred in Wenchuan earthquake region from 2008 to 2010, resulting in great damage to localities and being a prolonged threat to reconstruction. Forty three events' data including debris-flow volume, sediment volume and watershed area are analyzed and compared with other debris-flow events in Eastern Italian Alps, burned areas in USA and in Taiwan. The analysis reveals that there is a strong empirical relationship between debris-flow volume and loose materials volume in the earthquake region. In addition, the relationship between debris-flow volume and watershed area in the earthquake region has a wider variation range than that in other three regions while the debris volume also appears to be larger than that in the other three regions, which implies the volume of debris flows with strong influence of earthquakes is larger than that with no such influence and it is hard to predict the post-quake volume only by the watershed area. The comparison of the maximal debris-flow erosion modulus in the Wenchuan region and in Taiwan indicates that debris flows will be very active in a short time after strong earthquake.
  PubDate: 2013-06-01
The 2010 Zhouqu mudflow disaster: possible causes, human contributions, and lessons learned
- Abstract: Abstract On August 7, 2010, a giant mudflow occurred in Zhouqu County, in China’s Gansu Province. It killed at least 1,467 people and destroyed many buildings. The extensive damage resulted partially from the impact of the swift mudflow, and partially from subsequent flooding caused by damming of the Bailong River, creating a lake. The mudflow had both internal and external causes. We discuss these in detail from the perspective of their relationship to human activities, with the goal of helping to provide advance warning of such disasters in the future.
  PubDate: 2013-06-01
A new type of human-made disaster from the frequent school bus accidents in China
- PubDate: 2013-06-01
Is it possible to rank hurricanes in a unique manner'
- Abstract: Abstract This paper demonstrates that there is no unique manner in which hurricanes can be ranked. Land-falling hurricanes during the period 1960–2012 on the east coast of the United States were considered in the research. Hurricanes can be ranked using various criteria, and therefore, ranking can be different according to the criterion used. A total of 30 hurricanes were found to stand out using ten different criteria to define the severity of the hurricanes.
  PubDate: 2013-06-01
Hydrological modeling of typhoon-induced extreme storm runoffs from Shihmen watershed to reservoir, Taiwan
- Abstract: Abstract Typhoon-induced extreme storm runoffs often cause flood hazards. In this study, a hydrological model (HEC-HMS) was applied to Shihmen watershed located in Taiwan. Three typhoon-induced storm events, with return period ranging from 1 to 90 years, were used in case studies to characterize storm runoff. With a 5-year storm for model calibration, model parameters were carefully calibrated through the comparison between model simulated and observed flows at a stream gage station. The calibrated model was then verified for a 90-year storm and a 1-year storm event. Results indicate that the calibrated and verified HEC-HMS hydrological model is capable of providing satisfactory predictions of the typhoon-induced extreme storm runoff to support reservoir operation and flood hazard mitigation. Based on model simulations, typhoon-induced water table increases for different initial water volumes at Shihmen Reservoir was derived by adding storm-runoff volume to the reservoir’s initial elevation-volume rating curve. Water tables above the top elevation of the dam in the reservoir indicate the need for immediate water releases to avoid the risk of overflow over the dam.
  PubDate: 2013-06-01
Evaluation of real-time flash flood forecasts for Haiti during the passage of Hurricane Tomas, November 4–6, 2010
- Abstract: Abstract The January 2010 earthquake that devastated Haiti left its population ever more vulnerable to rainfall-induced flash floods. A flash flood guidance system has been implemented to provide real-time information on the potential of small (~70 km2) basins for flash flooding throughout Haiti. This system has components for satellite rainfall ingest and adjustment on the basis of rain gauge information, dynamic soil water deficit estimation, ingest of operational mesoscale model quantitative precipitation forecasts, and estimation of the times of channel flow at bankfull. The result of the system integration is the estimation of the flash flood guidance (FFG) for a given basin and for a given duration. FFG is the amount of rain of a given duration over a small basin that causes minor flooding in the outlet of the basin. Amounts predicted or nowcasted that are higher than the FFG indicate basins with potential for flash flooding. In preparation for Hurricane Tomas’ landfall in early November 2010, the FFG system was used to generate 36-h forecasts of flash flood occurrence based on rainfall forecasts of the nested high-resolution North American Model of the National Centers for Environmental Prediction. Assessment of the forecast flood maps and forecast precipitation indicates the utility and value of the forecasts in understanding the spatial distribution of the expected flooding for mitigation and disaster management. It also highlights the need for explicit uncertainty characterization of forecast risk products due to large uncertainties in quantitative precipitation forecasts on hydrologic basin scales.
  PubDate: 2013-06-01
Seismic damage to urban areas due to failed buried fuel pipelines case study: fire following earthquake in the city of Kermanshah, Iran
- Abstract: Abstract Oil Pipeline and Telecommunication Company of West Region is one of the eleven regional branches of Iranian Oil Pipeline and Telecommunication Companies (IOPTC) and is responsible for the transfer of crude oil and oil products through 129, 236, and 179 km pipelines in the western region of Iran in the provinces of Kermanshah, Kurdestan, and Ilam and Lorestan, respectively. This paper, in respect of damage analysis, concentrates on the assessment of fuel pipeline systems buried underneath the city of Kermanshah, failure in pipelines and post-earthquake fires. In order to assess the seismic damage to buried fuel pipelines of Kermanshah with the help of characteristics and information of network components, PGA and PGV values are initially determined for two probable earthquake scenarios in the study area, using the attenuation relations derived for the same area. Then, using the repair rate relations, damage to pipelines is estimated. Furthermore, the consequences of the release of oil materials from the pipelines and their ignition are analyzed using the logic tree. The probability distribution function for the area, the population, and the number of houses exposed to fire and explosion after the earthquake are calculated using the Monte Carlo simulation method through numerous repetitions (10,000 times). All the steps of damage assessment for buried pipelines were written in a GIS environment. Two proposed mitigation strategies for fire damage reduction in the Kermanshah area are investigated in the second stage, and the damage is investigated by repeating the process. In order to give a better description of the output results, the probability distribution functions for each output are provided. In summary, the damage inflicted on the fuel pipelines of Kermanshah is equal to 17 leaks, 5 breaks, and 21 ignitions for earthquake scenario 1, which was reduced to 2 ignitions after mitigation strategy 1. Comparing mitigation strategies 1 and 2 in earthquake scenario 1, it is concluded that although the ratio of assumed reduction of ignition probabilities of strategy 2 to strategy 1 is 0.5, the relative reductions gained in the strategy 2 are 78.95, 75.98, 83.83, and 78.90 % with respect to strategy 1 for number of ignitions, affected area, number of fatalities, and number of buildings exposed to explosion, respectively. The proposed method could be used in other similar cases and also as a platform for further supplementary analyses.
  PubDate: 2013-06-01
Application of a feature-based approach to debris flow detection by numerical simulation
- Abstract: Abstract A debris flow is a serious natural disaster which can occur anywhere whether in a valley or on a mountain slope, destroying everything it passes through. Debris flows can occur suddenly and cause residents in the path to suffer casualties and property loss. An early warning system is necessary to reduce the damage in order to protect human life and personal property. However, most debris flow detection systems, like wireless sensors, satellite images and radar, are not suitable for general public use. Vision surveillance systems are generally erected in Taiwan as public devices for security. Therefore, we propose a novel debris early warning system that uses a computer vision technique and build a simulation environment to prove the feasibility.
  PubDate: 2013-06-01
Meteorological drought over the Chinese Loess Plateau: 1971–2010
- Abstract: Abstract In this study, the Variable Infiltration Capacity model and Palmer Drought Severity Index (PDSI) were combined for drought identification on the Loess Plateau. The calibration method of climatic characteristic (K j ) in PDSI was improved. Land cover datasets in 1980 and 2005 were used to drive the model. The driest periods over the past four decades of the study region emerged in 1976–1982, 1997–2001 and 2003–2008. Regardless of ranking by duration, spatial extent or severity, most of the prominent droughts occurred in the detected driest periods. The drought severity and area over the upper reaches of the Yellow River were higher than other domains. A total of 53 droughts with area greater than the 25,000 km2 threshold were identified with durations longer than 3 months using clustering algorithm. Most regions of the study area exhibited spatially increasing trends in drought severity and frequency, indicating that the Loess Plateau has experienced apparent drying and warming processes between 1971 and 2010.
  PubDate: 2013-06-01