共查询到20条相似文献，搜索用时 31 毫秒
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Drought events are increasing worldwide. Socio-economic drought is the least investigated type of drought, and is the only type for which water demand is taken into consideration. In this research, socio-economic drought was studied in Lake Mead, USA, using a multivariate standardized water-scarcity index (MSWSI) over the period 1990–2014, combining two water-scarcity indices based on time series of inflow, outflow, reservoir storage, and water demand. The inflow and outflow were determined from streamgage data, and reservoir storage from lake level data; demand was based on water pumped by the Southern Nevada Water Authority. Missing observations in input streamgage data were filled through regression modeling. The results indicate that Lake Mead has been in socio-economic drought since 2000, with the most severe drought occurring between 2006 and 2012, and the highest intensity drought in April–July 2014. The Lake Mead droughts revealed through the MSWSI are consistent with those reported in US Drought Monitor (USDM) products. The temporal behavior of MSWSI provides an insight into the socio-economic effects of droughts not captured by USDM products. 相似文献
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D. E. Villalta L. Bravo de Guenni A. M. Sajo-Castelli 《Stochastic Environmental Research and Risk Assessment (SERRA)》2020,34(3):513-529
Extreme environmental events have considerable impacts on society.
Preparation to mitigate or forecast accurately these events is a growing concern for governments. In this regard, policy and decision makers require accurate tools for risk estimation in order to take informed decisions. This work proposes a Bayesian framework for a unified treatment and statistical modeling of the main components of risk: hazard, vulnerability and exposure. Risk is defined as the expected economic loss or population affected as a consequence of a hazard event. The vulnerability is interpreted as the loss experienced by an exposed population due to hazard events. The framework combines data of different spatial and temporal supports. It produces a sequence of temporal risk maps for the domain of interest including a measure of uncertainty for the hazard and vulnerability. In particular, the considered hazard (rainfall) is interpolated from point-based measured rainfall data using a hierarchical spatio-temporal Kriging model, whose parameters are estimated using the Bayesian paradigm. Vulnerability is modeled using zero-inflated distributions with parameters dependent on climatic variables at local and large scales. Exposure is defined as the total population settled in the spatial domain and is interpolated using census data. The proposed methodology was applied to the Vargas state of Venezuela to map the spatio-temporal risk for the period 1970–2006. The framework highlights both high and low risk areas given extreme rainfall events. 相似文献
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An insight into the Palmer drought mechanism based indices: comprehensive comparison of their strengths and limitations 总被引：2，自引：2，他引：0
Yi Liu Liliang Ren Mingwei Ma Xiaoli Yang Fei Yuan Shanhu Jiang 《Stochastic Environmental Research and Risk Assessment (SERRA)》2016,30(1):119-136
Considering the drawbacks of the original Palmer drought severity index (PDSI) in terms of its simplified hydrologic algorithm and spatio-temporal inconsistency, we compare six variants of PDSI derived from different combinations of two hydrologic algorithms and three standard processes so as to provide deep insights into the individual impacts of hydrological processing and standardization on final PDSI values as well as their combined effects. Investigations are conducted in whole Yellow River basin. On basis of 52 years’ (1961–2012) hydro-meteorological data, comprehensive analysis on multiple drought characteristics are carried out for each PDSI variant, combined with comparison of three crucial intermediate variables of PDSI. Results show that variable infiltration capacity (VIC) model based modification in the hydrologic accounting section significantly improve drought trends with more reasonable spatial distributions presented. For the statistical characteristics of drought areas and frequency, comparable performance is found between VIC-based modification and self-calibrating standard procedure-based modification, though they are derived from different mechanisms. However, in case of the coupling of these two modifications, indices derived from combined modifications perform poorly than single modification-based indices with unexpected high frequency of extreme events detected in certain regions. This reflects the complicated mechanism of PDSI and it is essential to propose an appropriate standardization to match the hydrological algorithm and further improve the performance of relevant drought index. With the crucial findings mentioned above, this study is promising to provide some theoretical supports and serve as a competent reference for future PDSI based researches. 相似文献
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Multivariate drought characteristics using trivariate Gaussian and Student t copulas 总被引：4，自引：0，他引：4
This study aims to investigate the changing properties of drought events in Weihe River basin, China, by modeling the multivariate joint distribution of drought duration, severity and peak using trivariate Gaussian and Student t copulas. Monthly precipitations of Xi'an gauge are used to illustrate the meta‐elliptical copula‐based methodology for a single‐station application. Gaussian and Student t copulas are found to produce a better fit comparing with other six symmetrical and asymmetrical Archimedean copulas, and, checked by the goodness‐of‐fit tests based on a modified bootstrap version of Rosenblatt's transformation, both of them are acceptable to model the multivariate joint distribution of drought variables. Gaussian copula, the best fitting, is employed to construct the dependence structures of positively associated drought variables so as to obtain the multivariate joint and conditional probabilities of droughts. A Kendall's return period (KRP) introduced by Salvadori and De Michele (2010) is then adopted to assess the multivariate recurrent properties of drought events, and its spatial distributions indicate that prolonged droughts are likely to break out with rather short recurrence intervals in the whole region, while drought status in the southeast seems to be severer than the northwest. The study is of some merits in terms of multivariate drought modeling using a preferable copula‐based method, the results of which could serve as a reference for regional drought defense and water resources management. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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ABSTRACTThe estimation of drought at certain temporal and spatial scales is useful for research on climate change and global warming. Greece is often affected by droughts, which are widespread spatially and temporally due to the complex topography. Within the Greek territory, various complex microclimates are created, linked with the spatial variances in drought phenomena. In this paper an estimation of drought in the Sperchios River basin was conducted using the Aridity Index (AI). Additionally, a seasonal analysis of drought was performed. Meteorological data from the Hellenic National Meteorological Service (HNMS) were used as inputs for the AI equation. Spatial interpolation of AI for the Sperchios River basin was performed using a kriging method by the application of ArcGIS 9.3. In order to produce required input data, several models (EmPEst, RayMan) and techniques (linear regression, interpolation) were combined. Finally, the meteorological data series were randomly separated into two periods and AI was estimated for these sub-periods, in order to test the effectiveness of the drought index used. The results indicate that the conditions prevailing in the area are humid, mostly affected by increased rainfall occurring in the mountainous section of the basin. Broadly, the humid environment in the upstream of Sperchios River prevents drought occurring in the lowlands of Sperchios River valley. Nevertheless, some differentiation appeared during the summer period, to which special attention needs to be given in order to prevent drought conditions.
Editor Z. W. Kundzewicz Associate editor not assigned 相似文献
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MIKE BONELL 《水文科学杂志》2013,58(5):809-810
Abstract Since droughts are natural phenomena, their occurrence cannot be predicted with certainty and thus it must be treated as a random variable. Once drought duration and magnitude have been found objectively, it is possible to plan for the transport of water in known quantities to drought-stricken areas either from alternative water resources or from water stored during wet periods. The summation of deficits over a particular period is referred to as the drought magnitude. Drought intensity is the ratio of drought magnitude to its duration. These drought properties at different truncation levels provide significant hydrological and hydrometeorological design quantities. In this study, the run analysis and z-score are used for determining drought properties of given hydrological series. In addition, kriging is used as a spatial drought analysis for mapping. This study is applied to precipitation records for Istanbul, Edirne, Tekirdag and Kirklareli in the Trakya region, Turkey and then the drought period, magnitude and standardized precipitation index (SPI) values are presented to depict the relationships between drought duration and magnitude. 相似文献
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极端干旱事件中洞庭湖水面变化过程及成因 总被引：2，自引：0，他引：2
干旱是洞庭湖区长期以来面临的严重自然灾害之一,给周边人们的生产生活造成了极大的影响.针对2006和2011年洞庭湖区发生的极端干旱事件,借助遥感影像大范围、时空连续的优势,结合湖区水文气象等观测资料,从时空两方面阐释了洞庭湖在典型干旱年份水域分布及变化过程,进一步从温度、降水、径流以及蓄水量等方面对比分析不同干旱事件发生、发展过程的一致性和差异性.研究结果表明:2006年干旱大致从7月开始,至12月结束.水面淹没范围由湖心向周边扩展,到7月达到最大值,8月提前进入枯水期,减小范围主要集中在东洞庭湖外围和南洞庭湖的北边.2006年干旱属于由入湖径流减少主导的水文干旱事件;2011年的干旱则从4月开始,至11月结束,在9月以后干旱继续加重.水面淹没范围在6月急剧增大且一直到8月都维持在较高的水平,涨水期水面由中心向四周淹没,退水期水面变化范围与涨水期相反.2011年干旱是由流域降水减少引起的水文和气象干旱事件.研究结果揭示了洞庭湖区干旱成因的多样性和复杂性,对于制定科学合理的干旱灾害防范措施,减缓区域的生态环境问题等具有一定的指导和借鉴意义. 相似文献
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In Part 1 we demonstrated the applicability of stochastic models to predicting the characteristics of point drought events within any planning period by means of a case study (Mohan S, Sahoo PK (2007) Hydrological Processes 21 : this issue). In addition, studies on regional droughts are important in the context of regional level planning and evolving management strategies. The small number of drought events from a particular streamflow or rainfall series, when subjected to statistical analysis in order to predict future occurrences, produces results that are not very reliable. To overcome this difficulty, we propose using a long sequence of synthetically generated annual rainfall series at various rain‐gauge stations of a region, and multiyear regional droughts were derived from both historic and generated series. The key parameters for a successful regional multiyear drought study are the critical area ratio and the critical level, and the area affected by the drought can be ascertained using these parameters. The important regional drought parameters were determined and their suitable probability distributions were arrived at by studying a total of nine possible probability models; these models can be used in predicting the longest regional drought duration and the greatest regional drought severity with a given return period. The effect of change of critical parameters on the regional drought parameters is also studied and reported. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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Development of an operational low-flow index for hydrological drought monitoring over Europe 总被引：1，自引：1，他引：0
Near real-time monitoring of hydrological drought requires the implementation of an index capable of capturing the dynamic nature of the phenomenon. Starting from a dataset of modelled daily streamflow data, a low-flow index was developed based on the total water deficit of the discharge values below a certain threshold. In order to account for a range of hydrological regimes, a daily 95th percentile threshold was adopted, which was computed by means of a 31-day moving window. The observed historical total water deficits were statistically fitted by means of the exponential distribution and the corresponding probability values were used as a measure of hydrological drought severity. This approach has the advantage that it directly exploits daily streamflow values, as well as allowing a near real-time update of the index at regular time steps (i.e. 10 days, or dekad). The proposed approach was implemented on discharge data simulated by the LISFLOOD model over Europe during the period 1995–2015; its reliability was tested on four case studies found within the European drought reference database, as well as against the most recent summer drought observed in Central Europe in 2015. These validations, even if only qualitative, highlighted the ability of the index to capture the timing (starting date and duration) of the main historical hydrological drought events, and its good performance in comparison with the commonly used standardized runoff index (SRI). Additionally, the spatial evolution of the most recent event was captured well in a simulated near real-time test case, suggesting the suitability of the index for operational implementation within the European Drought Observatory. 相似文献
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Multi-scale analysis of meteorological drought risks based on a Bayesian interpolation approach in Huai River basin,China 总被引：4，自引：4，他引：0
Kai Duan Weihua Xiao Yadong Mei Dedi Liu 《Stochastic Environmental Research and Risk Assessment (SERRA)》2014,28(8):1985-1998
A scheme for meteorological drought analysis at various temporal and spatial scales based on a spatial Bayesian interpolation of drought severity derived from Standardized Precipitation Index (SPI) values at observed stations is presented and applied to the Huai River basin of China in this paper, using monthly precipitation record from 1961 to 2006 in 30 meteorological stations across the basin. After dividing the study area into regular grids, drought condition in gauged sites are classified into extreme, severe, moderate and non drought according to SPIs at month, seasonal and annual time scales respectively while that in ungauged grids are explained as risks of various drought severities instead of single state by a Bayesian interpolation. Subsequently, temporal and spatial patterns of drought risks are investigated statistically. Main conclusions of the research are as follows: (1) drought at seasonal scale was more threatening than the other two time scales with a larger number of observed drought events and more notable variation; (2) results of the Mann–Kendall test revealed an upward trend of drought risk in April and September; (3) there were larger risks of extreme and severe drought in southern and northwestern parts of the basin while the northeastern areas tended to face larger risks of moderate drought. The case study in Huai River basin suggests that the proposed approach is a viable and flexible tool for monitoring meteorological drought at multiple scales with a more specific insight into drought characteristics at each severity level. 相似文献
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M. Janga Reddy Vijay P. Singh 《Stochastic Environmental Research and Risk Assessment (SERRA)》2014,28(3):475-489
This study investigated the utility of two meta-heuristic algorithms to estimate parameters of copula models and for derivation of drought severity–duration–frequency (S–D–F) curves. Drought is a natural event, which has huge impact on both the society and the natural environment. Drought events are mainly characterized by their severity, duration and intensity. The study adopts standardized precipitation index for drought characterization, and copula method for multivariate risk analysis of droughts. For accurate estimation of copula model parameters, two meta-heuristic methods namely genetic algorithm and particle swarm optimization are applied. The proposed methodology is applied to a case study in Trans Pecos, an arid region in Texas, USA. First, drought severity and duration are separately modeled by various probability distribution functions and then the best fitted models are selected for copula modeling. For modeling the joint dependence of drought variables, different classes of copulas, namely, extreme value copulas, Plackett and Student’s t copulas are employed and their performance is evaluated using standard performance measures. It is found that for the study region, the Gumbel–Hougaard copula is the best fitted copula model as compared to the others and is used for the development of drought S–D–F curves. Results of the study suggest that the meta-heuristic methods have greater utility in copula-based multivariate risk assessment of droughts. 相似文献
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Heilongjiang Province is a major grain production base in China, and its agricultural development plays an important role in China’s social economy. Drought and flood events are the primary disasters in Heilongjiang Province and have considerable impacts on agriculture. In this study, relatively complete monthly precipitation data from 26 meteorological stations in Heilongjiang Province during the period of 1958–2013 were analyzed using the standardized precipitation index (SPI) combined with principal component analysis, Mann–Kendall trend analysis and Morlet wavelet analysis to determine the spatial and temporal distributions of drought and flood events in this province. The results were as follows: (1) the whole of Heilongjiang exhibited an aridity trend. In northern Heilongjiang, spring and summer experienced a wetting trend, and autumn and winter experienced an aridity trend. (2) The SPI3 exhibited 8- and 16-year periodic variation characteristics in spring, 10- and 22-year periodic variation characteristics in summer, and 10- and 32-year periodic variation characteristics in autumn. In addition to the 10-year periodic variation characteristics in winter, other periodic variation characteristics were observed. (3) The increasing trend in the percentage of stations affected by flood was more obvious than that affected by drought. Therefore, Heilongjiang Province is more vulnerable to flooding. (4) The influence of drought and flood disasters in Heilongjiang Province showed a growth trend, but the flood effect was more remarkable. (5) The agricultural area affected by drought and flood disasters in Heilongjiang Province showed an increasing trend. Although there was a greater increase in flood disaster area, the main types of disasters were drought-dominated. 相似文献
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2009年秋至2010年春我国西南地区干旱及与历史场次干旱对比分析 总被引：4，自引：0，他引：4
2009年10月至2010年4月,我国西南地区由于受厄尔尼诺影响,气温偏高、降雨偏少,发生了秋冬春三季连旱,耕地受旱面积占全国同期耕地受旱面积的78%,受灾人口和大牲畜饮水困难头数都达到了近十年来该地区的最高水平。通过对比本次和历史场次干旱发现,西南干旱并非稀遇现象,1951~1990年的40年间该地区曾发生干旱12次,且1949年以来,干旱有缓慢加重的趋势;本次旱灾与1963年旱灾在时空分布、灾害成因和灾情方面较为相似,但从气象干旱的角度来看,虽然1963年部分受旱地区无有效降雨历时为11个月,高于本次旱灾的6个月,但本次受灾率和成灾率均为1949年以来的最大值,说明在快速发展背景下,经济社会面对干旱显得更为脆弱。这些结论对于认清西南地区干旱特性与旱灾演变规律,加强抗旱减灾体系建设,具有重要的参考价值。 相似文献
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António M. Lopes J. A. Tenreiro Machado C. M. A. Pinto A. M. S. F. Galhano 《Journal of Seismology》2014,18(1):163-179
Earthquakes are associated with negative events, such as large number of casualties, destruction of buildings and infrastructures, or emergence of tsunamis. In this paper, we apply the Multidimensional Scaling (MDS) analysis to earthquake data. MDS is a set of techniques that produce spatial or geometric representations of complex objects, such that, objects perceived to be similar/distinct in some sense are placed nearby/distant on the MDS maps. The interpretation of the charts is based on the resulting clusters since MDS produces a different locus for each similarity measure. In this study, over three million seismic occurrences, covering the period from January 1, 1904 up to March 14, 2012 are analyzed. The events, characterized by their magnitude and spatiotemporal distributions, are divided into groups, either according to the Flinn–Engdahl seismic regions of Earth or using a rectangular grid based in latitude and longitude coordinates. Space-time and Space-frequency correlation indices are proposed to quantify the similarities among events. MDS has the advantage of avoiding sensitivity to the non-uniform spatial distribution of seismic data, resulting from poorly instrumented areas, and is well suited for accessing dynamics of complex systems. MDS maps are proven as an intuitive and useful visual representation of the complex relationships that are present among seismic events, which may not be perceived on traditional geographic maps. Therefore, MDS constitutes a valid alternative to classic visualization tools, for understanding the global behavior of earthquakes. 相似文献
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Ognjen Bonacci 《水文研究》1993,7(3):249-262
The problem of drought identification is considered from a primarily hydrological viewpoint. The problems related to the definition, identification and prediction of drought have not yet been solved. Although rainfall data are analysed as the main indicator and characteristic of drought, other characteristics resulting from a rainfall deficit are also important. A time unit of one month was selected as the most suitable for analysis. Special attention was paid to the selection of truncation levels with respect to their influence on the results of drought identification. Three methods for drought identification were applied to a series of monthly rainfall data in Osijek from January 1882 to December 1990: (1) run analysis; (2) a discrete Markov process; and (3) the percentile method. Although the results of these three methods are encouraging, different methods yielded similar results. Some drawbacks of the application of distribution curves are discussed. Drought events should be identified using a number of different procedures. 相似文献
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Droughts are natural phenomena that severely affect socio economic and ecological systems. In Chile, population and economic activities are highly concentrated in its central region (i.e. between latitudes 29°S and 40°S), which periodically suffers from severe droughts affecting agriculture, hydropower, and mining. Understanding the dynamics of droughts and large-scale atmospheric processes that influence the occurrence of dry spells is essential for forecasting and efficient early detection of drought events. Central Chile's climate is marked by a significant El Niño Southern Oscillation (ENSO) influence that might help to better characterize droughts as well as to identify the effects of ENSO on the spatial and temporal characteristics of meteorological and hydrological droughts in the region. We analysed the behaviour of the Standardized Precipitation Evapotranspiration Index (SPEI) and Standardized Streamflow Index (SSI) time series for 6-month accumulation periods over the austral winter and summer seasons. Multiple linear regression (MLR) and Generalized Linear Models (GLM) showed a significant ENSO influence on dry events for SPEI-6 and SSI-6 during winter and summer. We found that the magnitude of correlation between ENSO and SPEI-6 has changed over the last decades becoming weaker in winter periods and increasing in spring summer periods. Increasing trends in meteorological and hydrological drought events were also identified, along all latitudes, with significant trends during winter in the southern latitudes, and during summer in the semi-arid and Mediterranean zones. These results indicate that drought mitigation actions and policies are necessary to overcome their adverse effects. Given the monthly persistence of ENSO and its relationship to drought indices, there are opportunities for drought monitoring and seasonal forecasting that could become part of national drought management systems. 相似文献
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Khouloud Gader Ahlem Gara Marnik Vanclooster Slaheddine Khlifi Mohamed Slimani 《水文科学杂志》2020,65(8):1300-1315
ABSTRACT Predicting the impacts of climate change on water resources remains a challenging task and requires a good understanding of the dynamics of the forcing terms in the past. In this study, the variability of precipitation and drought patterns is studied over the Mediterranean catchment of the Medjerda in Tunisia based on an observed rainfall dataset collected at 41 raingauges during the period 1973–2012. The standardized precipitation index and the aridity index were used to characterize drought variability. Multivariate and geostatistical techniques were further employed to identify the spatial variability of annual rainfall. The results show that the Medjerda is marked by a significant spatio-temporal variability of drought, with varying extreme wet and dry events. Four regions with distinct rainfall regimes are identified by utilizing the K-means cluster analysis. A principal component analysis identifies the variables that are responsible for the relationships between precipitation and drought variability. 相似文献
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Yue-Ping Xu Martijn J. Booij Yang-Bin Tong 《Stochastic Environmental Research and Risk Assessment (SERRA)》2010,24(5):567-578
With the increase of both magnitude and frequency of hydrological extreme events such as drought and flooding, the significance
of adequately modeling hydrological extreme events is fully recognized. Estimation of extreme rainfall/flood for various return
periods is of prime importance for hydrological design or risk assessment. However, due to knowledge and data limitation,
uncertainty involved in extrapolating beyond available data is huge. In this paper, different sources of uncertainty in statistical
modeling of extreme hydrological events are studied in a systematic way. This is done by focusing on several key uncertainty
sources using three different case studies. The chosen case studies highlight a number of projects where there have been questions
regarding the uncertainty in extreme rainfall/flood estimation. The results show that the uncertainty originated from the
methodology is the largest and could be >40% for a return period of 200 years, while the uncertainty caused by ignoring the
dependence among multiple hydrological variables seems the smallest. In the end, it is highly recommended that uncertainty
in modeling extreme hydrological events be fully recognized and incorporated into a formal hydrological extreme analysis. 相似文献