تحليل فراواني منطقه اي دوره هاي خشك هيدرولوژيك با استفاده از روش گشتاورهاي خطي در حوزه آبخيز درياي خزر

چكيده انگليسي :

Regional Hydrologic Dry Spells Frequency Analysis by L Moments Method in the Caspian Sea Basin Mohammad Mirghafourian Email Adrdress m mirghafourian@gmail com September Department of Natural Resources Isfahan University of Technology Isfahan Iran Degree M Sc Language Farsi Abstract Unexpected events frequency and magnitude in hydrology like occurrence probability severity and duration of hydrological drought in most parts of world have great deal of importance so that evaluation of draughts occurrence probability and duration serve as an stochastic analysis on dry spells In the present study two above mentioned characteristics for drought were evaluated on hydrometric stations selected in Caspian Sea basin to predict and estimate drought severity and duration To drought severity and its duration regional frequency analysis linear moment s method was used Out of total hydrometric stations located at Caspian sea basin stations were selected due to having suitable statistical period for regional frequency analysis and at the same time maximum dry days and number of drought events were calculated as hydrological severity and duration parameters in every station respectively After homogeneity and stochastic tests of data homogeneity statistic H developed by Hosking and Wallis was calculated to test study area homogeneity suggested that study area is completely heterogeneous To achieve homogenous area analysis of hierarchy process AHP was applied to classify studied basins into eight and ten classes in intensity and duration section Using linear moments method and after eliminating heterogeneous stations the classes homogeneity was approved as per H statistic H According to good of fitness test and using statistic ZDist two distributions of extended partto GPAR and Pearson type PIII were introduced for most of homogenous groups as appropriate regional distributions for parameters drought severity and duration Then FREQ program in software MATLAB was used to estimate hydrological drought severity and duration under different return periods and drought severity and duration values were calculated by fitting suitable frequency distribution on data from stations Then physiographical and climatic characteristics for upstream basin for each station were estimated To regional frequency analysis and evaluate relationship between different climatic and physiographical parameters and drought severity and duration under various return periods multivariate regression was applied and totally the number of nine physiographical and climatic were confirmed to prepare models Results of regional analysis indicated that mean annual rainfall mean basin slope basin shape factor mean basin elevation and mean main river slope were among the most determinant factor in study area hydrological drought Results obtained from the present research may be promising for water resource planning dam construction projects water supply for municipal and farming operation forward to improving drought comprehensive plans and critic management Keywords hydrological drought drought severity and duration regional frequency analysis Dry Spells linear moments multivariate regression Caspian Sea basin PDF created with pdfFactory trial version www pdffactory com

ميرغفوريان، محمد

تحليل فراواني منطقه اي دوره هاي خشك هيدرولوژيك با استفاده از روش گشتاورهاي خطي در حوزه آبخيز درياي خزر

شدت خشكسالي و مدت آن , رگرسيون چند متغيره