Monte Carlo analysis of the effect of spatial distribution of storms on prioritization of flood source areas   总被引：1，自引：0，他引：1  

Bahram Saghafian  Saeed Golian  Mohammad Elmi  Ruhangiz Akhtari 《Natural Hazards》2013,66(2):1059-1071

Implementation of structural and non-structural flood control measures in flood-prone watersheds is on increasing demand. Different watershed areas are not necessarily hydrologically similar and impose variable effects on the outlet flow hydrograph. Meanwhile, prioritization of watershed areas in terms of flood generation is essential for economic flood control planning. Previous works have focused on the definition of a flood index that quantifies the contribution of each subwatershed unit or grid cell to the outlet flood hydrograph through the application of unit flood response (UFR) approach. In the present research, for the first time, the effect of spatial pattern of storm events on the flood index variation was assessed via a Monte Carlo uncertainty analysis. To do so, the UFR approach was carried out for a large number of randomly generated rainfall spatial pattern. The proposed methodology was adopted to the Tangrah watershed in northern Iran. The watershed is frequently hit by floods that have historically caused loss of life and properties. The results indicated that for the more frequent flood events, the flood index is quite sensitive to the spatial distribution of rainfall such that for the highest ranked subwatershed (SW6), the standardized variation of the flood index values (i.e., the uncertainty range) decreases from 1.0 to 0.5 when the rainfall depth increases from 20 to 150 mm, respectively. The results further revealed that increasing the rainfall depth from 20 to 150 mm would cause the effect of rainfall spatial distribution on subwatersheds’ flood indices to diminish. The implications are that if flood control measures are designed for more frequent floods with lower return periods, an uncertainty analysis is required to identify the range of flood index variations.  相似文献   

A dynamic prediction model for time-to-peak     

Mistaya Langridge  Ed McBean  Hossein Bonakdari  Bahram Gharabaghi 《水文研究》2021,35(1):e14032

A simplified empirical equation is developed for widespread prediction of dynamic catchment response time. This model allows for time-to-peak prediction to evolve from static, lumped models, thereby providing a single value for any storm within a given catchment, using a single set of input parameters, that can be applied to a dynamic model, thus accounting for the variability between storm sizes and catchment moisture conditions. These dynamic prediction methods are translated to North America for the first time. This allows the concepts and prediction methods for catchment response time prediction previously established for the United Kingdom (UK), to be translated to a simple empirical equation for use in North America, through the use of selected study areas in Canada and the United States. This reconfigured model is statistically successful in both the UK and North America and allows for a straightforward implementation of dynamic time-to-peak prediction. Further, the reconfigured model introduces the use of a runoff coefficient (R_c) to encompass historical catchment wetness, increasing the ease of incorporating antecedent moisture condition into predictions.  相似文献   

A new daily weather generator to preserve extremes and low-frequency variability     

Mohammad Reza Khazaei  Shahin Ahmadi  Bahram Saghafian  Bagher Zahabiyoun 《Climatic change》2013,119(3-4):631-645

This paper addresses deficiencies of stochastic Weather Generators (WGs) in terms of reproduction of low-frequency variability and extremes, as well as the unanticipated effects of changes to precipitation occurrence under climate change scenarios on secondary variables. A new weather generator (named IWG) is developed in order to resolve such deficiencies and improve WGs performance. The proposed WG is composed of three major components, including a stochastic rainfall model able to reproduce realistic rainfall series containing extremes and inter-annual monthly variability, a multivariate daily temperature model conditioned to the rainfall occurrence, and a suitable multi-variate monthly generator to fit the low-frequency variability of daily maximum and minimum temperature series. The performance of IWG was tested by comparing statistical characteristics of the simulated and observed weather data, and by comparing statistical characteristics of the simulated runoff outputs by a daily rainfall-runoff model fed by the generated and observed weather data. Furthermore, IWG outputs are compared with those of the well-known LARS-WG weather generator. The tested characteristics are a variety of different daily statistics, low-frequency variability, and distribution of extremes. It is concluded that the performance of the IWG is acceptable, better than LARS-WG in the majority of tests, especially in reproduction of extremes and low-frequency variability of weather and runoff series.  相似文献   

An ultraviolet-selected galaxy redshift survey – III. Multicolour imaging and non-uniform star formation histories     

Mark Sullivan  Marie A. Treyer  Richard S. Ellis  Bahram Mobasher 《Monthly notices of the Royal Astronomical Society》2004,350(1):21-34

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Incorporating synoptic-scale climate signals for streamflow modelling over the Mediterranean region using machine learning models     

Ozgur Kisi  Bahram Choubin  Ravinesh C. Deo 《水文科学杂志》2013,58(10):1240-1252

ABSTRACT

Understanding streamflow patterns by incorporating climate signal information can contribute remarkably to the knowledge of future local environmental flows. Three machine learning models, the multivariate adaptive regression splines (MARS), the M5 Model Tree and the least squares support vector machine (LSSVM) are established to predict the streamflow pattern over the Mediterranean region of Turkey (Besiri and Baykan stations). The structure of the predictive models is built using synoptic-scale climate signal information and river flow data from antecedent records. The predictive models are evaluated and assessed using quantitative and graphical statistics. The correlation analysis demonstrates that the North Pacific (NP) and the East Central Tropical Pacific Sea Surface Temperature (Niño3.4) indices have a substantial influence on the streamflow patterns, in addition to the historical information obtained from the river flow data. The model results reveal the utility of the LSSVM model over the other models through incorporating climate signal information for modelling streamflow.  相似文献   

K- and Si-Metasomatism, Mineral Transformation and Formation of Granitoids from Basic Rocks in Qooshchi Area, NW Iran. A Mineralogical Context     

PouranBehnia LorenceGCollins BahrainASamani 《中国地质大学学报(英文版)》2003,14(1):34-41

The Qooshchi area lies to northwest of Orumieh Lake in western Azerbaijan, NW Iran. A basement metamorphic complex, consisting of Precambrian schists and gneisses, has been intruded by gabbres and diorites. Granitolds are grouped into five suites according to their mineralogy, texture and exposed features. The main body, pink Qooshchi granite, and apophyse-like, myrmekite-bearing granit-oids are discussed in this paper. On the basis of field observations and microscopic studies, an intensive metasonmtism has overprinted the country rocks, especially gabbros, transforming them into a more felsic composition. A prior event of intensive deformation and cataclasis preceded the metasonmtism, al-lowing the introduction of hydrothermal fluids. K-metasonmtism converted plagiuclase into K-feldspar (microdme), myrmekite, and sodic plagioclase as Si-metasomatism replaced the ferromagnesian silicates by quartz. Apophyse-like bodies within gabbros, called leucometasomatites, are formed during this process.  相似文献   

Wetland classification in Newfoundland and Labrador using multi-source SAR and optical data integration     

Meisam Amani  Bahram Salehi  Sahel Mahdavi  Jean Granger  Brian Brisco 《地理信息系统科学与遥感》2017,54(6):779-796

A vast portion of Newfoundland and Labrador (NL) is covered by wetland areas. Notably, it is the only province in Atlantic Canada that does not have a wetland inventory system. Wetlands are important areas of research because they play a pivotal role in ecological conservation and impact human activities in the province. Therefore, classifying wetland types and monitoring their changes are crucial tasks recommended for the province. In this study, wetlands in five pilot sites, distributed across NL, were classified using the integration of aerial imagery, Synthetic Aperture Radar, and optical satellite data. First, each study area was segmented using the object-based method, and then various spectral and polarimetric features were evaluated to select the best features for identifying wetland classes using the Random Forest algorithm. The accuracies of the classifications were assessed by the parameters obtained from confusion matrices, and the overall accuracies varied between 81% and 91%. Moreover, the average producer and user accuracies for wetland classes, considering all pilot sites, were 71% and 72%, respectively. Since the proposed methodology demonstrated high accuracies for wetland classification in different study areas with various ecological characteristics, the application of future classifications in other areas of interest is promising.  相似文献   

Land Subsidence Susceptibility Zonation of Isfahan Plain Based on Geological Bedrock Layer     

Fatolahzadeh  Sina  Nadi  Bahram  Ajalloeian  Rassoul 《Geotechnical and Geological Engineering》2022,40(4):1989-1996

Geotechnical and Geological Engineering - In the present paper, the effect of the depth of the bedrock layer on the land subsidence of the Isfahan plain was studied. The geological bedrock layer...  相似文献   

Evolutionary Prediction of Biohydrogen Production by Dark Fermentation     

Azam Akhbari  Shaliza Ibrahim  Ali A. Zinatizadeh  Hossein Bonakdari  Isa Ebtehaj  Zohre S. Khozani  Mohsen Vafaeifard  Bahram Gharabaghi 《洁净——土壤、空气、水》2019,47(1)

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Leveling geochemical data between map sheets   总被引：1，自引：0，他引：1  

Bahram Daneshfar  Eion Cameron   《Journal of Geochemical Exploration》1998,63(3):189-201

Geochemical surveys are frequently assembled into larger, regional compilations. In some cases a boundary shift in the values for one or more elements may be observed at the join of adjacent surveys. This indicates that data for the affected elements are not consistent between the surveys. Where the same sampling medium has been used, the shift may be due to different crews/organizations, who varied in their sampling techniques. However, most commonly the shift is due to imperfect calibration of the analytical method used for samples from the different surveys. For example, there may have been a lack of proper analytical standardization between survey programs. To carry out leveling, bands are established on either side of the boundary between two surveys that show a shift. It is desirable that the bands have a close match in terms of geology and physiography. A quantitative method is presented to estimate the optimum width for these bands. Quantiles of the data within each band are calculated. The quantile pairs are plotted in X–Y space and a line fitted to express the relationship between the pairs of quantiles. The equation of this line is used to correct the shift between the two surveys. This method is tested on data for Mo in stream sediments, and pH of stream water, from two National Geochemical Reconnaissance Surveys in British Columbia.  相似文献