نشریه علمی - پژوهشی مرتع و آبخیزداری

نوع مقاله : مقاله پژوهشی

نویسندگان

1 استادیار دانشکدة منابع طبیعی دانشگاه کردستان

2 استاد دانشکدة منابع طبیعی دانشگاه تهران

3 استادیار مؤسسة علوم زمین و منابع طبیعی (BGR) ژئوسنتروم هانوفر، آلمان

4 دانشیار دانشکدة منابع طبیعی دانشگاه تهران

چکیده

با جدی‏ترشدن مسئلة تغییر اقلیم و آثار احتمالی آن بر سیستم‌های منابع آب، طراحی و اجرای برنامه‏های مدیریتی، با فرض شرایط هیدرولوژیکی ثابت، می‏تواند مدیریت و برنامه‏ریزی را با چالش جدی در پیش‏بینی دقیق نیازهای آتی روبه‌رو کند. بر این اساس، در مطالعة حاضر تلاش شده است روند تغییرات متغیرهای هیدرواقلیمی در ایستگاه‏هایی با آمار طولانی‌مدت در سراب کرخه، با استفاده از روش «من- کندال اصلاح‌شده برای اثر خودهمبستگی»، سری‏های روزانة دما، بارش و دبی بررسی شود. بیشتر متغیرهای دما روند افزایشی داشت و نتایج بررسیِ بارش نیز دارای تفاوت‏های مکانی بود. به طور کلی، روند کاهشی برای جریان در منطقه مشاهده شد و این تغییرات در جریان‏های پایه شدیدتر بود. روند کاهشی میانة دبی سالانه در ایستگاه‏ هولیلان در سطح ده درصد معنی‏دار شد. بارش سالانه، تعداد روزهای بارانی و تعداد روزهایِ با بارشِ بیش از 10 میلی‏متر همبستگیِ معنی‏دارِ بیشتری با متغیرهای جریان نشان دادند. بررسی روابط دبی ماهانه با متغیرهای بارش و دما در ایستگاه‏های مورد بررسی نشان‌دهندة تأخیرِ واکنش سیستم به ورودی‏هاست؛ این موضوع می‏تواند به تأخیرِ ذوب برف یا عبور جریان از مسیرهای آبی دیگر، مانند آب زیرزمینی، مربوط باشد. بخشی از تغییراتِ متغیرهای جریان، به‌ویژه در دبی‏های پایه، کاملاً با بارش توجیه نمی‏شود و می‏تواند از تغییرات دما یا عواملی مانند افزایش بهره‏برداری از آب زیرزمینی متأثر باشد.
 
 

کلیدواژه‌ها

عنوان مقاله [English]

Trend analysis of streamflow in Karkheh Rivers upstream: An evidence for climate change impacts on water resources systems

نویسندگان [English]

  • Khaled Osati 1
  • Ali Salajegheh 2
  • Mohammad Mahdavi 2
  • Paul Koeniger 3
  • Kamran Chapi 1
  • Arash Malekian 4

1 Assistant professor, University of Kurdistan

2 Professor, Faculty of Natural Resources, University of Teheran

3 Federal Institute for Geosciences and Natural Resources (BGR), Geozentrum Hannover, Germany.

4 Associate professor, Faculty of Natural Resources, University of Teheran

چکیده [English]

Within the climate change debate and its probable impacts on water resources systems, design and operation of management plans based on the assumption of stationary hydrology may cause serious challenge to accurately predict future supplies. Therefore this case study is trying to assess trend in hydroclimatic variables of Karkheh Rivers upstream by applying modified Mann-Kendall trend test on long term daily time series of temperature, precipitation and discharge. Temperature variables are mostly showing meaningful increasing trends but observed changes in assessed stations were not spatially uniform for precipitation. Streamflow variables depict a decreasing trend, though more noticeable in base flows. Decreasing trend is meaningful for annual discharge median in Holailan at 90% confidence level. Total yearly precipitation, number of precipitation days and number of days with precipitation equal to, or greater than, 10 mm/d show the most correlation with stream flow variables. Comparing monthly discharge with temperature and precipitation variables in the studied gages indicates a time-delay in system response to inputs. This may related to snowmelt contributions or contributions of water into streams after passing through different hydrological pathways such as groundwater. Some parts of streamflow changes, especially about base flows, is not completely verified by precipitation changes and can be attributed to changes in temperature or another factors such as groundwater overexploitation.
 
 

کلیدواژه‌ها [English]

  • Modified Mann- Kendall
  • Karkheh
  • Autocorrelation
  • time series
  • climate change

 

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