Investigation of the importance of rainy days in predicting the flow duration curve of arid and semi-arid regions

کاظمی, رحیم and داودي, حميد (2018) Investigation of the importance of rainy days in predicting the flow duration curve of arid and semi-arid regions. In: The 13th National Conference on Watershed Management Science & Engineering of Iran and The 3rd National Conference on Conservation of Natural Resources and Environment, 3-4 October 2018, Ardabil, Iran. (Submitted)

[img] Text (بررسي اهميت تعداد روزهاي باراني در پيش¬بيني منحني تداوم جريان درمناطق خشك و نيمه¬خشك)
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Abstract

Improvement and development of predictions in ungagged catchments requires recognizing effective factors and understanding the interactions between different components of the catchments and hydrological response in different climate zones. In this research, the catchments in each climatic region were first separated by intersecting of climatic map and the border map of the watersheds. Then, at least thirty hydrometric stations with appropriate statistics and common period of 1976-2011 were selected from each climatic region. FDC extracted using daily flow data and then indicators of Q2, Q5, Q10, Q15, Q20, Q50, Q75, and Q90 were selected. Then, the average of rainy days for each catchment was calculated. Finally, the regression relations between the FDC indicators and the average of number of rainy days in different climatic regions were extracted and analyzed. The study of the trend of the mean values of FDC indices from the different climatic zone can be found that in FDC of the catchments in very humid zone, the first major inflection point occurred on the Q20 to Q50 indices. And in the wet zone, the first inflection point was in the Q75 and Q90. In the semi-humid area, two inflection points can be observed, one between Q15 and Q20, and the second one passing through Q20 to Q50. The same trend can be seen in FDC of the semi-arid and the dry zone between Q20 to Q50. Changes in the position of the inflection point of FDC in different climates are the reflection of the influence of various geometric, hydrological and climatic components. These changes necessitate attention to the exact recognition of the type of parameters and their effectiveness. The results showed that the average coefficient of determination for low flow indices (Q75 and Q90) with the average annual rainy days in catchments of different climatic zones was approximately equal to 0.66.However, the relationship between the numbers of rainy days with the Q2-Q50 indices does not show a good correlation.Therefore, it is suggested that in arid and semi-arid regions, the number of rainy days as a predictive parameter for estimating the indices of the end section of FDC should be used and the use for estimating other indices is not recommended. Keywords: Flow duration curve, climate region, Hydrologic parameters, Number of rainy days,

Item Type: Conference or Workshop Item (Poster)
Persian Title: بررسي اهميت تعداد روزهاي باراني در پيش¬بيني منحني تداوم جريان درمناطق خشك و نيمه¬خشك
Persian Abstract: شناخت مولفه¬هاي تاثيرگذار بر منحني تداوم جريان به بهبود و توسعه پیش¬بینی¬ها¬ در حوضه¬های فاقد آمار و درک برهم¬کنش بین مولفه-های مختلف حوضه و پاسخ هیدرولوژیک آن كمك مي¬كند. در این پژوهش ابتدا با تهیه نقشه اقلیم کشور و تقاطع آن با مرز حوزه¬های آبخیز رتبه چهار، حوضه¬های واقع در هر منطقه اقلیمی تفکیک شد. سپس تعداد حداقل سی ایستگاه آبسنجی با آمار مناسب و دوره مشترک آماری سال¬های1355-1390در هر منطقه اقلیمی انتخاب شد. منحنی تداوم جریان با استفاده از داده¬هاي دبي روزانه ترسيم و شاخص¬هاي,Q2,Q5, Q10,Q15,Q20,Q50,Q75, Q90‌استخراج شد. سپس تعداد روز¬های بارانی برای هر حوضه محاسبه شد. روابط رگرسیونی بین شاخص¬هاي منحنی و تعداد روز¬هاي باراني سال در مناطق مختلف اقلیمی استخراج و تحلیل شد. نتایج نشان داد که در تمامي مناطق اقليمي میانگین ضریب تبیین شاخص¬هاي كم آبي شامل Q75 ,Q90‌ با میانگین سالانه تعداد روزهای بارانی تقریباً برابر و به میزان 66/0 می¬باشد. ولي رابطه تعداد روز¬هاي باراني با شاخص¬هاي Q2 الي Q50 همبستگي مناسبي را نشان نمي دهد. لذا پيشنهاد مي¬شود در مناطق خشك و نيمه¬خشك از مولفه تعداد روزهاي باراني به¬عنوان پارامتر پيش¬بيني كننده براي برآورد شاخص¬هاي بخش انتهايي منحني تداوم جريان استفاده شود و استفاده براي برآورد ساير شاخص¬ها توصيه نمي¬شود. واژگان كليدي: منحنی تداوم جریان، مناطق اقلیمی، پارامتر¬های هیدرو لوژیکی، تعداد روز¬هاي باراني
Subjects: Divisions > Conferences > The 13th National Conference on Watershed Management Science & Engineering of Iran and The 3rd National Conference on Conservation of Natural Resources and Environment
Conferences > The 13th National Conference on Watershed Management Science & Engineering of Iran and The 3rd National Conference on Conservation of Natural Resources and Environment
Divisions: Conferences > The 13th National Conference on Watershed Management Science & Engineering of Iran and The 3rd National Conference on Conservation of Natural Resources and Environment
Subjects > Conferences > The 13th National Conference on Watershed Management Science & Engineering of Iran and The 3rd National Conference on Conservation of Natural Resources and Environment
Date Deposited: 21 Oct 2018 07:31
Last Modified: 21 Oct 2018 07:31
URI: http://repository.uma.ac.ir/id/eprint/1084

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