مشخصه‌های بارش سالانه و فصلی در ناحیة رویشی صحارا-سندی

نوع مقاله : مقاله پژوهشی

نویسندگان

1 گروه جنگلداری و اقتصاد جنگل، دانشکدة منابع طبیعی، دانشگاه تهران، کرج، ایران.

2 گروه احیا مناطق خشک و کوهستانی، دانشکدة منابع طبیعی، دانشگاه تهران، کرج، ایران.

10.22059/jfwp.2024.369765.1277

چکیده

هدف از انجام این پژوهش، بررسی مشخصه­ های بارش شامل مقدار و تعداد رخدادهای بارش در ناحیة رویشی صحارا-سندی در سه دهة اخیر بود. با استفاده از داده ­های بارش روزانة 33 ساله (1398-1366) 18 ایستگاه هواشناسی همدیدبانی در این ناحیة رویشی، مقدار بارش و تعداد رخداد بارش سالانه ارزیابی و از آزمون من‌کندال برای معنی­داری روندهای سالانه و فصلی استفاده شد. در دورة 33 ساله، میانگین بارش سالانه در ناحیة صحارا-سندی، 214 میلی­ متر (انحراف معیار 61 میلی­ متر) بود. بیشترین میانگین بارش سالانه در ایستگاه دوگنبدان (439 میلی­ متر) و کمترین آن در ایستگاه ایرانشهر (109 میلی­ متر) ثبت شد. از 18 ایستگاه این ناحیه، تنها در دو ایستگاه رام هرمز و جزیرة­ کیش (11 درصد از کل روندها)، بارش سالانه روند معنی­داری نشان داد. در طول 33 سال، در ایستگاه ­های ناحیة صحارا-سندی، درمجموع، 17275 رخداد (میانگین رخداد 7/5 میلی­ متر و انحراف معیار 9/6 میلی‌متر) ثبت شد. ضریب همبستگی (r) مقدار بارش و تعداد رخداد سالانه، از 0/41 تا 0/86 (میانگین: 0/67 و انحراف معیار 0/13 میلی­ متر) متغیر بود. نتایج نشان داد که 83 درصد از بارش سالانه، در فصول پاییز و زمستان رخ داده است. بیشترین و کمترین درصد بارش سالانه به‌ترتیب در طبقه‌های 40-20 میلی­ متر (21 درصد، 45 میلی ­متر) و بیش از 40 میلی­ متر (30 درصد، 64 میلی ­متر) رخ داده بود. در طی سال­ های مورد مطالعه، میانگین تعداد روز خشک سال در این ناحیة رویشی، 336 روز بود. هر گونه تغییر در مشخصه ­های بارش، به‌طور مستقیم بر بوم‌سازگان ­های جنگلی آسیب ­پذیر این ناحیة رویشی، تأثیرگذار است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Annual and seasonal precipitation characteristics in the Saharo-Sindian vegetation region

نویسندگان [English]

  • Saeede Salehi Vaziri 1
  • Pedram Attarod 1
  • Shahram Khalighi Sigaroodi 2
  • Hamid Soofi Mariv 1
1 Department of Forestry and Forest Economics, Faculty of Natural Resources, University of Tehran, Karaj, Iran.
2 Department of Reclamation of Arid and Mountainous Region, Faculty of Natural Resources, University of Tehran, Karaj, Iran.
چکیده [English]

In the present study, we detected the characteristics of precipitation (the amount and the number of events) in the Saharo-Sindian vegetation region located in the south and southeast of Iran over the last three decades. Daily precipitation data during 1987-2019, recorded by eighteen meteorological stations were analyzed. The Mann-Kendall (MK) test was used for trend analysis. Over the past thirty-three years, the mean annual precipitation was 214 mm (SD: 61 mm). Mean maximum and minimum yearly precipitations were recorded in Dogonbadan (439 mm) and Iranshahr (109 mm), respectively. Out of the eighteen stations, only two stations, Ramhormoz and Kish Island, showed significant annual precipitation trends (11% of the total trends). During 33 years, a total of 17275 events (mean event: 7.5 mm; SD: 6.9 mm) were recorded in the stations. The correlation coefficient (r) between the amount of precipitation and the number of events varied from 0.41 to 0.86 (mean: 0.67; SD: 0.13). We found that 83% of the mean annual precipitation occurred during the autumn and winter seasons. The highest and lowest yearly precipitations fell within the 20-40 mm (21%, 45 mm) and over 40 mm (30%, 64 mm) classes, respectively. Over the past three decades, the mean number of dry days per year was 336. Any changes in precipitation characteristics severely impact the vulnerable forest ecosystems in the Saharo-Sindian vegetation region.

کلیدواژه‌ها [English]

  • Mann-Kendall
  • Meteorological stations
  • Precipitation event. Trending
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