بررسی روند تغییرات بارش و دبی در حوضه آبریز دریاچه اورمیه در طول چهار دهه اخیر

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانش آموخته کارشناسی ارشد آبخیزداری دانشکده مرتع و آبخیز، دانشگاه علوم کشاورزی و منابع طبیعی گرگان

2 دانشیار گروه مرتع و آبخیز، دانشگاه علوم کشاورزی و منابع طبیعی گرگان

3 استادیار گروه مهندسی آب و پژوهشکده دریاچه اورمیه، دانشگاه اورمیه

چکیده

حوضه دریاچه اورمیه به دلیل اهمیت اقلیمی، اقتصادی، اکولوژیک و زیست محیطی یکی حوضه­های مهم در شمال­غرب ایران به­شمار می­رود. در این مطالعه به منظور بررسی علل افت سطح آب دریاچه، روند دو عامل دخیل در تغذیه آن، شامل بارش و دبی رودخانه­ها مورد مطالعه قرار گرفت. برای این منظور، داده­های مربوط به ایستگاه­های باران­سنجی و هیدرومتری در سرتاسر حوضه در مقیاس فصلی و سالانه جمع آوری گردید. سری زمانی طولانی مدت متغیرها تهیه شد و روند زمانی آنها با استفاده از آزمون من­کندال و کندال فصلی بررسی شد. نتایج نشان داد متغیر بارندگی سالانه در برخی نقاط روند افزایشی و در برخی روند کاهشی دارد اگرچه از نظر آماری روندهای مشاهده شده در اغلب ایستگاهها معنی­دار نیستند. علیرغم عدم وجود نشانه­هایی از روند کاهشی یکنواخت بارندگی سالانه، در بیشتر ایستگاه­های هیدرومتری متغیر دبی سالانه در سطح معنی­داری 5 درصد روند کاهشی دارد. بنابراین، به­طور آماری نمی­توان افت چشمگیر آبدهی رودخانه­های منتهی به دریاچه و در نتیجه افت سطح آب دریاچه را به کاهش مقدار بارندگی آن نسبت داد. در نتیجه عوامل دیگری از جمله افزایش روند تبخیر- تعرق ناشی از گرمایش اتمسفر، برداشت بی­رویه از آب­های زیرزمینی، تغییر کاربری اراضی و یا حتی ذخیره آب در مخازن سدها و کاهش جریان­های ورودی به مخزن دریاچه ممکن است باعث افت سطح آب دریاچه شده­اند که نیازمند تحقیقات بیشتر است

کلیدواژه‌ها

عنوان مقاله [English]

Study of Trends in Precipitation and Stream Flow of the Lake Urmia Basin During the Past Four Decades

نویسندگان [English]

  • P Fazli Fard 1
  • V Sheikh 2
  • A Sadoddin 2
  • B Hessari 3
1 M.Sc. Graduate, Watershed Management Engineering, Faculty of Range and Watershed Management, Gorgan University of Natural Resources and Agricultural Sciences, Iran
2 Assoc. Prof., Faculty of Range and Watershed Management, Gorgan University of Natural Resources and Agricultural Sciences, Iran
3 Assist. Prof., Water Engineering Department, Urmia Lake Research Institute Urmia University, Iran
چکیده [English]

The Lake Urmia basin in North West of Iran is one of the important basins of this country due to its climatological, economical, ecological and environmental condition. In this study in order to discover the likely causes of the lake shrinkage, trends of the two effective factors on its inflows (precipitation and rivers discharge), were investigated. For this purpose, rain gauges and hydrometric stations data at seasonal and annual scale across the basin were collected. Long time-series of variables were prepared and their trends were analyzed using the Mann-Kendall and seasonal Kendall test. According to the results although annual precipitation indicated decreasing or increasing trends at some stations, but most of them were not significant at 0.05 probability level. Despite lack of significant, decreasing trend for annual precipitation across the basin, the majority of hydrometric stations showed significant decreasing trend in the annual stream flow data at 0.05 probability level. Therefore, from statistical point of view, the significant decline at annual discharge of the streams draining into the lake and the shrinkage of the lake cannot be attributed to decline at annual precipitation. Therefore, some other causes such as increase in evapotranspiration due to atmospheric warm-up. Over-extraction of aquifers, extensive landuse changes, impoundment of water behind numerous dams and decline at the lake inflows might be effective on the Lake Urmia shrinkage.

کلیدواژه‌ها [English]

  • Discharge
  • Hydro climate
  • Mann Kendall
  • Non-Parametric
  • Urmia Lake

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دانش آب و خاک
دوره 29، شماره 4
دی 1398
صفحه 27-41

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