Climate extreme and its linkage to regional drought over Idaho, USA   总被引：2，自引：0，他引：2  

Mohammad M. Sohrabi  Jae H. Ryu  John Abatzoglou  John Tracy 《Natural Hazards》2013,65(1):653-681

To investigate consequences of climate extreme and variability on agriculture and regional water resource, twenty-seven climatic indices of temperature and precipitation over Idaho, USA, were computed. Precipitation, mean temperature and maximum temperature, self-calibrated Palmer Drought Index and Standardized Precipitation Index for 1-, 3-, 6- and 12-month time scales were used to identify spatial and temporal distribution of climatic extreme and variability as well as drought frequency and magnitude. Seven oceanic indices were also used to detect teleconnections between climatic indices and regional droughts. The analyses were conducted for 56 meteorological stations, during 1962?C2008, characterized by a long-term and high-quality data set. The result indicates that decreasing trends and increasing trends are identified for precipitation and temperature, respectively. Consequently, it appears that frost and ice days dwindle as growing season (May?CAugust) length, tropical nights and summer days increase. Given current climate conditions, the results also imply that these trends will continue in the future possibly driven by uncertain climate variability. We anticipate that these indices explained by teleconnections will improve drought-forecasting capability in this region.  相似文献   

Application of factor analysis in defining drought prone areas in Lake Urmia Basin     

Marzie Ghorbani-Aghdam  Yagob Dinpashoh  Ali Mostafaeipour 《Natural Hazards》2013,69(1):267-277

Data reduction methods such as principal components analysis and factor analysis can be used to define drought prone areas of a basin. In this study, factor analysis method applied for the purpose of projecting the information space on the few dominant axes. The main aim of this study is regionalization of Lake Urmia Basin from the view of drought using factor analysis. For this purpose, monthly precipitation data of 30 weather stations in the period 1972–2009 were used. For each of the selected stations, 3- and 12-month Standardized Precipitation Index (SPI) values were calculated. Factor analysis conducted on SPI values to delineate the study area with respect to drought characteristics. Homogeneity of obtained regions tested using the S statistics proposed by Wiltshire. Results of factor analysis of 3- and 12-month SPI values showed that 5 (6) factors having eigenvalues >1 accounted for 68.08 (78.88) % of total variance. The Lake Urmia Basin was delineated into the five distinct homogeneous regions using the 3-month SPI time series. This was six in the case of the 12-month SPI time series. It can be concluded that there are different distinct regions in Lake Urmia Basin according to drought characteristics. The map of regions defined using the 3- and 6-month SPI time series presented in this paper for Lake Urmia Basin.  相似文献   

Evaluation of liquefaction in Karasu River floodplain after the October 23, 2011, Van (Turkey) earthquake     

Akin  Mutluhan  Ozvan  Ali  Akin  Muge K.  Topal  Tamer 《Natural Hazards》2013,69(3):1551-1575

Natural Hazards - The eastern shore of Lake Van was shaken by a powerful earthquake (M w 7.2) on October 23, 2011. The epicenter of the earthquake was located at about 30 km north of the...  相似文献   

Forecasting of meteorological drought using Wavelet-ANFIS hybrid model for different time steps (case study: southeastern part of east Azerbaijan province, Iran)     

Bagher Shirmohammadi  Hamidreza Moradi  Vahid Moosavi  Majid Taie Semiromi  Ali Zeinali 《Natural Hazards》2013,69(1):389-402

Drought is accounted as one of the most natural hazards. Studying on drought is important for designing and managing of water resources systems. This research is carried out to evaluate the ability of Wavelet-ANN and adaptive neuro-fuzzy inference system (ANFIS) techniques for meteorological drought forecasting in southeastern part of East Azerbaijan province, Iran. The Wavelet-ANN and ANFIS models were first trained using the observed data recorded from 1952 to 1992 and then used to predict meteorological drought over the test period extending from 1992 to 2011. The performances of the different models were evaluated by comparing the corresponding values of root mean squared error coefficient of determination (R ²) and Nash–Sutcliffe model efficiency coefficient. In this study, more than 1,000 model structures including artificial neural network (ANN), adaptive neural-fuzzy inference system (ANFIS) and Wavelet-ANN models were tested in order to assess their ability to forecast the meteorological drought for one, two, and three time steps (6 months) ahead. It was demonstrated that wavelet transform can improve meteorological drought modeling. It was also shown that ANFIS models provided more accurate predictions than ANN models. This study confirmed that the optimum number of neurons in the hidden layer could not be always determined using specific formulas; hence, it should be determined using a trial-and-error method. Also, decomposition level in wavelet transform should be delineated according to the periodicity and seasonality of data series. The order of models with regard to their accuracy is as following: Wavelet-ANFIS, Wavelet-ANN, ANFIS, and ANN, respectively. To the best of our knowledge, no research has been published that explores coupling wavelet analysis with ANFIS for meteorological drought and no research has tested the efficiency of these models to forecast the meteorological drought in different time scales as of yet.  相似文献   

A study on selection of probability distributions for at-site flood frequency analysis in Australia   总被引：1，自引：0，他引：1  

Ayesha S. Rahman  Ataur Rahman  Mohammad A. Zaman  Khaled Haddad  Amimul Ahsan  Monzur Imteaz 《Natural Hazards》2013,69(3):1803-1813

The most direct method of design flood estimation is at-site flood frequency analysis, which relies on a relatively long period of recorded streamflow data at a given site. Selection of an appropriate probability distribution and associated parameter estimation procedure is of prime importance in at-site flood frequency analysis. The choice of the probability distribution for a given application is generally made arbitrarily as there is no sound physical basis to justify the selection. In this study, an attempt is made to investigate the suitability of as many as fifteen different probability distributions and three parameter estimation methods based on a large Australian annual maximum flood data set. A total of four goodness-of-fit tests are adopted, i.e., the Akaike information criterion, the Bayesian information criterion, Anderson–Darling test, and Kolmogorov–Smirnov test, to identify the best-fit probability distributions. Furthermore, the L-moments ratio diagram is used to make a visual assessment of the alternative distributions. It has been found that a single distribution cannot be specified as the best-fit distribution for all the Australian states as it was recommended in the Australian rainfall and runoff 1987. The log-Pearson 3, generalized extreme value, and generalized Pareto distributions have been identified as the top three best-fit distributions. It is thus recommended that these three distributions should be compared as a minimum in practical applications when making the final selection of the best-fit probability distribution in a given application in Australia.  相似文献   

Investigation of spatio-temporal patterns of seasonal streamflow droughts in a semi-arid region     

Saadat  Samane  Khalili  Davar  Kamgar-Haghighi  Ali Akbar  Zand-Parsa  Shahrokh 《Natural Hazards》2013,69(3):1697-1720

Natural Hazards - Spatio-temporal patterns of seasonal streamflow droughts were investigated for the semi-arid Karkheh watershed, located in western Iran with an area of 41,470 km2,...  相似文献   

Nature and onset age of neotectonic regime in the northern core of Isparta Angle,SW Turkey     

Ali Koçyiğit  Şule Gürboğa  Doğan Kalafat 《Geodinamica Acta》2013,26(1-2):52-85

The Isparta Angle (IA) is a reverse Λ-shaped morphotectonic structure located to the north of Antalya Gulf in the Eastern Mediterranean Sea. It resulted from the northward curvature of the originally E–W-trending Tauride orogenic belt owing to the nappe emplacements and related clockwise and anti-clockwise rotations in a time period of Early Paleocene to Early Pliocene. The IA is included in the southwest Anatolian tensional neotectonic domain and characterized by a series of grabens and horsts bounded by active normal faults of dissimilar length and trend. The evolutionary history of the graben-horst system is episodic. It is evidenced by two graben fills. These are older and modern (younger) graben fills separated by an intervening angular unconformity. The modern graben fill is nearly flat-lying (non-deformed) whereas older graben fill was deformed into a series of anticlines and synclines with ENE-trending curvi-linear axes by a short-term compressive tectonic regime operated in NNW–SSE direction during Late Pliocene. The diagnostic structures taking a part in the development of grabens and shaping the northern section of the IA are the margin-boundary normal faults. They occur in numerous single and several fault zones displaying a basin ward facing step-like land shape. Most of fault segments, particularly the master faults, are active and have a capacity of creating destructive earthquakes with a magnitude (up to Mw?=?7.0). This is evidenced by both the historical and instrumental period earthquakes. Both the focal mechanism solution of earthquakes and the stereographic plots of slip-plane data, measured on the active margin-boundary faults of various grabens comprising the IA, on the Schmidt lower hemisphere net obviously reveal that the IA is under the influence of the tensional neotectonic regime, not a compressive tectonic regime, i.e. the sinistral strike-slip shearing along the Pliny arc has not propagated yet onshore, and its commencement age is Early Quaternary.  相似文献   

Approximate formulas for rotational effects in earthquake engineering   总被引：1，自引：0，他引：1  

Mohammad Reza Falamarz-Sheikhabadi  Mohsen Ghafory-Ashtiany 《Journal of Seismology》2012,16(4):815-827

The paper addresses the issue of researching into the engineering characteristics of rotational strong ground motion components and rotational effects in structural response. In this regard, at first, the acceleration response spectra of rotational components are estimated in terms of translational ones. Next, new methods in order to consider the effects of rotational components in seismic design codes are presented by determining the effective structural parameters in the rotational loading of structures due only to the earthquake rotational components. Numerical results show that according to the frequency content of rotational components, the contribution of the rocking components to the seismic excitation of short period structures can never be ignored. During strong earthquakes, these rotational motions may lead to the unexpected overturning or local structural damages for the low-rise multi-story buildings located on soft soil. The arrangement of lateral-load resisting system in the plan, period, and aspect ratio of the system can severely change the seismic loading of wide symmetric buildings under the earthquake torsional component.  相似文献   

Effects of Operational Parameters on Decolorization of C. I. Acid Red 88 by UV/H2O2 Process: Evaluation of Electrical Energy Consumption     

Nasser Modirshahla  Mohammad A. Behnajady  Rajab Rahbarfam  Aydin Hassani 《洁净——土壤、空气、水》2012,40(3):298-302

In the present study, effects of operational parameters on the electrical energy consumption for photooxidative process (UV/H₂O₂) for the decolorization of C. I. Acid Red 88 (AR88) have been investigated. In a series of experiments, 20 mg L^?1 of AR88 solution were irradiated in the presence of different concentrations of H₂O₂ (to find out optimum amount of H₂O₂) by UV light intensity of 30 W m^?2 for certain irradiation times. The decolorization of the dye followed pseudo first‐order kinetics, and hence, the figure‐of‐merit electrical energy per order (E_EO) is appropriate for estimating the electrical energy efficiency. The electrical energy consumption was determined during the variation of some parameters such as initial H₂O₂ concentration, initial dye concentration, UV light intensity, pH, and the gap size of solution. Results showed that electrical energy could be reduced by optimizing operational parameters.  相似文献   

Bridge pier scour mitigation under steady and unsteady flow conditions   总被引：1，自引：1，他引：0  

Ali Tafarojnoruz  Roberto Gaudio  Francesco Calomino 《Acta Geophysica》2012,60(4):1076-1097

Watercourse morphology is affected by local scouring when the flow interferes with anthropic structures. Controlling the scour hole size is of predominant importance to guarantee bridge safety as well as to limit the variations of river morphology. A combined countermeasure against bridge pier scour is proposed and tested in order to reduce the maximum scour depth and deviate it away from the bridge foundation. In the first part of the laboratory campaign, combination of two countermeasures (bed-sill and collar) was evaluated for a circular pier under clear-water and live-bed steady flow conditions. The proposed combined countermeasure exhibited an efficiency of about 64% in terms of scour depth reduction. Afterwards, it was tested in unsteady flow conditions, first for a circular pier, then in the case of a rectangular pier with round nose and tail, two circular in-line piers and two rectangular in-line piers, under a hydrograph with a peak flow velocity slightly above the threshold condition of sediment motion. Results showed that the combined countermeasure had an efficiency of about 63% for a single circular pier; however, higher efficiency (about 75%) was obtained in applications to rectangular pier and two in-line circular or rectangular piers.  相似文献