investigation of relationship between hydrologic processes of precipitation, evaporation and stream flow using linear time series models (case study: western basins of lake urmia)
introduction: studying the hydrological cycle, especially in large scales such as water catchments, is difficult and complicated despite the fact that the numbers of hydrological components are limited. this complexity rises from complex interactions between hydrological components and environment. recognition, determination and modeling of all interactive processes are needed to address this issue, but it's not feasible for dealing with practical engineering problems. so, it is more convenient to consider hydrological components as stochastic phenomenon, and use stochastic models for modeling them. stochastic simulation of time series models related to water resources, particularly hydrologic time series, have been widely used in recent decades in order to solve issues pertaining planning and management of water resource systems. in this study time series models fitted to the precipitation, evaporation and stream flow series separately and the relationships between stream flow and precipitation processes are investigated. in fact, the three mentioned processes should be modeled in parallel to each other in order to acquire a comprehensive vision of hydrological conditions in the region. moreover, the relationship between the hydrologic processes has been mostly studied with respect to their trends. it is desirable to investigate the relationship between trends of hydrological processes and climate change, while the relationship of the models has not been taken into consideration. the main objective of this study is to investigate the relationship between hydrological processes and their effects on each other and the selected models. material and method: in the current study, the four sub-basins of lake urmia basin namely zolachay (a), nazloochay (b), shahrchay (c) and barandoozchay (d) were considered. precipitation, evaporation and stream flow time series were modeled by linear time series. fundamental assumptions of time series analysis namely normalization and stationarity were considered. skewness test applied to evaluate normalization of evaporation, precipitation and stream flow time series and logarithmic transformation function executed for in order to improve normalization. stationarity of studied time series were evaluated by well-known powerful adf and kpss stationarity tests. time series model's order was determined using modified aicc test and the portmanteau goodness of fit test was used to evaluate the adequacy of developed linear time series models. man-kendall trend analysis was also conducted for the precipitation amount, the number of rainy days, the maximum precipitation with 24 hours duration, the evaporation and stream flow in monthly and annual time scales. results and discussion: inferring to the physical base of arma models provided by salas et al (1998), the precipitation has been considered independently and stochastically. if this assumption is not true in a given basin, it is expected that the ma component of stream flow discharge model be eliminated or washed out. this case occurred in basins a, b and c. in these basins, the behavior of precipitation and evaporation was autoregressive. it was observed that the stream flow discharge behavior also follows autoregressive models that had greater lags than precipitation and evaporation lags. this result proved that the precipitation, evaporation, and stream flow processes in the basin were regular processes. in basin d, the behavior of precipitation was stochastic and followed the ma model, which was related to the stochastic processes. in this basin, the stochastic behavior of precipitation affected the stream flow behavior, and it was observed that the stochastic term of ma also appeared in the stream flow. thus, this leads to decrease the memory of stream flow discharge. the fact that the ma component in the stream flow discharge was greater than the ma component in precipitation indicated that during the process of producing stream flow discharge from precipitation, the stochastic factors performed an important role. conclusion: a comprehensive investigation on hydrological time series models of precipitation, evaporation and stream flow were investigated in this study. the framework of the study consists of trend analysis using mann-kendall test and time series. trend analysis results indicate the significant changes of water resources in the studied area. it means that sustainable development in studied area is greatly threatened. the results of parallel modeling of precipitation, evaporation and stream flow time series showed that the behavior of stream flow models are greatly affected by precipitation models. in other words, this study evaluate the physical concept of arma models in real-world monthly time scale for three main hydrologic cycle components and suggest that considering parallel hydrological time series modeling could increase the accuracy to select a model for simulation and prediction of stream flow time series. in addition, it suggested that there is a relation between climate pattern and hydrological time series models.
the investigation of the relationship between type a and type b personalities and quality of translation
an investigation about the relationship between insurance lines and economic growth; the case study of iran
مطالعات قبلی بازار بیمه را به صورت کلی در نظر می گرفتند اما در این مطالعه صنعت بیمه به عنوان متغیر مستفل به بیمه های زندگی و غیر زندگی شکسته شده و هم چنین بیمه های زندگی به رشته های مختلف بیمه ای که در بازار بیمه ایران سهم قابل توجهی دارند تقسیم میشود. با استفاده از روشهای اقتصاد سنجی داده های برای دوره های 48-89 از مراکز ملی داده جمع آوری شد سپس با تخمین مدل خود بازگشتی برداری همراه با تعدادی ...15 صفحه اول
on the relationship between using discourse markers and the quality of expository and argumentative academic writing of iranian english majors
the aim of the present study was to investigate the frequency and the type of discourse markers used in the argumentative and expository writings of iranian efl learners and the differences between these text features in the two essay genres. the study also aimed at examining the influence of the use of discourse markers on the participants’ writing quality. to this end the discourse markers us...15 صفحه اول
the relationship between using language learning strategies, learners’ optimism, educational status, duration of learning and demotivation
with the growth of more humanistic approaches towards teaching foreign languages, more emphasis has been put on learners’ feelings, emotions and individual differences. one of the issues in teaching and learning english as a foreign language is demotivation. the purpose of this study was to investigate the relationship between the components of language learning strategies, optimism, duration o...15 صفحه اول
امروزه لباس در نظر ورزشکاران و کسانی که برای اوقات فراغت خود و یا برای رسیدن به اندامی متعادل، ورزش می کنند؛ بسیار با اهمیت است. احساس مطلوب از لباس در زمره خصوصیات راحتی پوشش می باشد. خصوصیات انتقال رطوبت لباس، در ارزیابی راحتی حسی و حرارتی منسوجات تولید شده از آن ها بسیار مهم است. هدف از این تحقیق، معرفی پارچه جدید است که متشکل از الیاف استبرق با خواص منحصر به فرد می باشد. استبرق لیف طبیعی تو...
the relationship between academic self-concept and academic achievement in english and general subjects of the students of high school
according to research, academic self-concept and academic achievement are mutually interdependent. in the present study, the aim was to determine the relationship between the academic self-concept and the academic achievement of students in english as a foreign language and general subjects. the participants were 320 students studying in 4th grade of high school in three cities of noor, nowshah...