تعیین وضعیت و تغییرات شاخص فصلی بارش در بخش مرکزی استان اردبیل

مصطفی‌زاده, رئوف; مهری, سونیا

doi:10.22092/wmej.2018.121560.1109

تعیین وضعیت و تغییرات شاخص فصلی بارش در بخش مرکزی استان اردبیل

نوع مقاله : پژوهشی

نویسندگان

¹ استادیار گروه منابع طبیعی، دانشکده‌ی کشاورزی و منابع‌طبیعی، دانشگاه محقق اردبیلی

² دانش‌آموخته‌ی‌ کارشناسی‌ارشد مهندسی آبخیزداری، دانشکده‌ی کشاورزی و منابع‌طبیعی، دانشگاه محقق اردبیلی

10.22092/wmej.2018.121560.1109

چکیده

بارش مهم‌ترین سنجه‌ی اقلیمی، بویژه در مناطق خشک بوده، و وضعیت آن حاصل برهم‌کنش عوامل فیزیکی و تغییرات مکانی‌زمانی است و از تغییر اقلیم متأثر می‌گردد. فصلی‌بودن نحوه‌ی توزیع بارندگی در ماه‌های سال را مشخص می‌کند، و به‌عبارتی تغییرات فصلی وضعیت بارش را ارزیابی می‌کند. بررسی حاضر برای تعیین وضعیت و تغییرات شاخص فصلی با استفاده از شاخص فصلی‌بودن و روند تغییرات آن در بخش مرکزی استان اردبیل انجام شده است. از داده‌های بارندگی 24 ایستگاه‌ باران‌سنجی در دوره‌ی آماری 1368 تا 1391 (23ساله) استفاده شد. تغییرات زمانی‌مکانی با استفاده از دو نمایه‌ی بارش، یعنی شاخص فصلی بارش و ضریب تغییرات برآورد شدند. روند شاخص فصلی با آزمون من-کندال تعیین شد. نتایج نشان دادند که بیش‌ترین ضریب تغییرات در ایستگاه لای و اردبیل به‌‌ترتیب با 65 و 63%، و کم‌ترین ضریب تغییرات در ایستگاه شمشیرخانی با 36% بود. براساس نتایج شاخص فصلی بارش، بخش عمده‌ی منطقه در دو وضعیت عمدتاً فصلی با یک فصل خشک کوتاه (2/0 تا 3/0)، و یکنواخت با یک فصل مرطوب و دامنه‌ی عددی بیشینه‌ی 6/0 بودند. نتایج روند با استفاده از آزمون من–کندال نشان دادند که فقط در برخی از این ایستگاه‌ها روند ازنظر آماری معنی‌دار بوده‌است. ارزیابی ضریب تغییرات بارش نشان داد که یکنواختی بارش در ماه‌های مختلف در این ایستگاه‌ها کاهش یافته‌است. افزایش ضریب تغییرات بارش و شاخص فصلی بارش بیانگر تغییر وضعیت آن و افزایش محتمل شدت خشک‌سالی در منطقه است.

کلیدواژه‌ها

عنوان مقاله [English]

Determination of the Precipitation Regime and the Seasonality Index Variations in the Central Part of the Ardabil Province

نویسندگان [English]

Raoof Mostafazadeh ¹
Sonia Mehri ²

¹ Assistant Professor, Department Natural Resources, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili

² Graduated M.Sc. of Watershed Management Engineering, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili

چکیده [English]

Precipitation is the most important climatic factor, particularly in dry lands and its regime characteristics is affected by the change in climate. The precipitation regime is a result of physical, spatial and temporal interactions. The seasonality index (SI) specifies the distribution of monthly rainfall over the year and evaluates the seasonal variations of the rainfall regime. The present study was conducted to determine the precipitation regime and to detect the trend of precipitation SI at the central part of the Province of Ardabil. The rainfall data of 24 stations were collected for the 1989–2012 period. Descriptive statistics of monthly precipitation data were presented both graphically and statistically, and the spatial-temporal variations were estimated using the SI and coefficient of variation (CV). The trend of precipitation SI at different rain gauge stations was determined using the Mann-Kendall test. The results showed that the highest CV belonged to the Sad-Ghorichay and Lay Stations (65 and 63%), and the lowest was related to the Shamsir Khani Station (36%). Based on the precipitation SI of monthly data, two main regimes were determined: a short dry-season (SI= 0.2–0.3), and a wet-season having the SI value of 0.6. The results of the Mann-Kendall test showed that most stations had either negative or positive trends in the precipitation SI. The increasing trend in the study area was more than the decreasing trend; only in some stations was the trend statistically significant. Also, assessing the CV of precipitation data showed that the uniformity of monthly precipitation values had decreased during the study period. Increasing the CV and precipitation SI indicate a change in precipitation regime; consequently, an increase in the severity of possible droughts in the study area.

کلیدواژه‌ها [English]

coefficient of variations
Mann–Kendall
precipitation regime
seasonality index
trend test

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