نشریه علمی - پژوهشی مرتع و آبخیزداری

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانش‌آموخته‌ دکترای گروه آبخیزداری، دانشکدۀ مرتع و آبخیزداری، دانشگاه علوم کشاورزی و منابع طبیعی گرگان، ایران

2 دانشیار گروه آبخیزداری، دانشکدۀ مرتع و آبخیزداری، دانشگاه علوم کشاورزی و منابع طبیعی گرگان، ایران

چکیده

تجزیه و تحلیل روند و ایستایی متغیرهای هیدرولوژیک، ابزارهایی مفید برای درک تغییرات اقلیمی هستند و می­توانند اطلاعات مفیدی را در مورد تغییرات محتمل در آینده فراهم نمایند. از آنجایی که ناایستایی سری­های زمانی می­تواند به دلایل مختلفی نظیر وجود روند در داده­ها رخ دهد، در تحقیق حاضر ابتدا آزمون­ ناپارامتری من-کندال همراه با روشی برای اصلاح تأثیر همبستگی سریالی بر روند (TFPW)، مورد استفاده قرار گرفتند؛ هم­چنین به جهت ارزیابی رابطه میان روند و ایستایی سری­های زمانی مورد بررسی، ایستایی سری­های زمانی توسط آزمون­های ایستایی بررسی گردید. یافته­های پژوهش حاضر نشان دادند که جریان سطحی در تمامی رودخانه­های اصلی مورد مطالعه در دامنه­های جنوبی البرز دارای روند کاهشی است. در ایستگاه­هایی که روند کاهشی معناداری از خود نشان دادند (لتیان و فیروزکوه)، استفاده از روش TFPW معناداری روند جریان سطحی را در ایستگاه­های مذکور از بین برد. نتایج آزمون­های ایستایی حاکی از ایستا بودن تمامی سری­ها پس از حذف همبستگی سریالی موجود در آن­ها است که این امر می­تواند متأثر از عدم وجود روند معنادار در این سری­ها باشد؛ با این حال ایستگاه فیروزکوه پس از اعمال روش TFPW ناایستایی معناداری در سطح اطمینان 95 درصد از خود نشان داد که این امر ممکن است ناشی از وجود جهش در سری داده­های این ایستگاه باشد. یافته­های پژوهش حاضر می­تواند به برنامه­ریزان و سیاست­گذاران در عرصه­های گوناگون مرتبط با برنامه­ریزی منابع آب کشور در انطباق با تغییرات اقلیمی در آینده یاری رساند.

کلیدواژه‌ها

عنوان مقاله [English]

Trend and stationarity patterns of surface flow time series in the Southern Slopes of Alborz Range

نویسندگان [English]

  • Mahsa Mirdashtvan 1
  • Ali Najafinejad 2
  • Amir Sadoddin 2

1 Gorgan University of Agricultural and Natural Resources

2 Gorgan University of Agricultural and Natural Resources

چکیده [English]

Trend and stationarity analyses of hydrological variables are useful tools for understanding climate change and may provide useful information about likely changes in the future. As non-stationary of time series can occur due to various reasons such as trend existence in data; therefor, in current study the non-parametric Mann-Kendall trend test was used to detect the trend of the data. A corrector approach, namely “TFPW” was utilized to modify the effects of serial dependence of the time series on the trend detection results. The stationarity of time series was tested by unit root and stationarity tests to evaluate the relationship between trend and stationarity of the time series. The results showed that the surface flows of all of the studied rivers have a decreasing trend; although the significant trends changed to insignificant ones after applying TFPW approach. The results of the stationarity tests showed non-stationary time series for all of the sites after removing the serial dependence of the series, which is a sign of the lack of trend existence in the time series; however, Latian station (Lar river) reveals non-stationarity after applying TFPW which may be originated from the existence of abrupt changes in the series. The findings of current study can help the planners and policy-makers and water resources managers to cope with climate change in the future.

کلیدواژه‌ها [English]

  • climate change
  • Southern slopes of Alborz
  • Stationarity
  • Surface flow
  • trend
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