بررسی تغییرات بلند مدت سالانه و فصلی کیفیت رودخانه (مطالعه موردی: رودخانه الشتر)

نوع مقاله: مقاله اصلی

نویسندگان

1 دانشجوی کارشناسی ارشد، گروه مهندسی آب، دانشکده کشاورزی، دانشگاه لرستان، خرم آباد، ایران

2 استادیار، گروه مهندسی آب، دانشکده کشاورزی، دانشگاه لرستان، خرم آباد، ایران

چکیده

گسترش شهرنشینی و فعالیت­های صنعتی و کشاورزی در حاشیه رودخانه الشتر و به­دنبال آن تخلیه پساب­ها به منابع آب باعث آلودگی آب به­وسیله آلاینده­های مختلف شده است. در این پژوهش به ارزیابی روند تغییرات بلندمدت کیفیت آب رودخانه الشتر به­صورت فصلی و سالانه ­پرداخته‌شد. برای انجام این پژوهش، از داده­های ثبت‌شده کیفیت آب در ایستگاه هیدرومتری سراب صید علی واقع در خروجی حوضه رودخانه الشتر از سال 1348 تا 1397 استفاده شد. جهت تجزیه‌وتحلیل، 11 متغیر کیفی آب انتخاب شد. برای بررسی روند تغییرات از آزمون من-کندال استفاده شد. نتایج نشان داد که الگوی تغییرات پارامترها در مقیاس­های سالانه و فصلی مشابه هم بوده است، ‌طوری‌که غلظت پارامترهای HCO3، Na، pH و SAR کاهش و غلظت عناصر Mg، Ca، TH، TDS،EC ،Cl  و SO4 افزایش داشت. در دوره­ی سالانه، روند تغییرات تمامی پارامترهای کیفی به­جز Na در سطح آماری 99% معنی‌دار بوده است. در فصول تابستان روند­های افزایشی شدید­تر و روند­های کاهشی ملایم‌تر رخ داد؛ به­طوری‌که شدید­ترین افزایش غلظت در این فصل اتفاق افتاده است. این در حالی است که در فصل زمستان نتایج بر­خلاف تابستان رخ داده­است. در فصل بهار نسبت به فصل پائیز در اغلب پارامتر­های کیفی، روند­های کاهشی بیش­تر و افزایشی کم­تر بوده است. دلیل این امر این است که در این منطقه در فصل بهار، ذوب برف­های زمستانه از ارتفاعات اتفاق می­افتد و باعث افزایش جریانات سطحی و کاهش نسبی غلظت­ها می­شود.

کلیدواژه‌ها


عنوان مقاله [English]

Investigating the Long-Term Annual and Seasonal Changes in River Quality (Case Study: Aleshtar River)

نویسندگان [English]

  • Yaser Sabzevari 1
  • Aryan Heidari Motlgh 1
  • Aliheidar Nasrolahi 2
1 M.Sc. Student, Water Engineering Department, Faculty of Agriculture, Lorestan University, Khorramabad, Iran
2 Assist.Professor, Water Engineering Department, Faculty of Agriculture, Lorestan University, Khorramabad, Iran
چکیده [English]

The expansion of urbanization along with industrial and agricultural activities on the banks of the Alshar River and subsequent discharge of wastewater into water sources have caused water contamination by various pollutants. In this study, seasonal and annual changes in the long-term water quality changes in the Alshar River were evaluated. For this purpose, water quality data used were recorded at the Sarab Sayyed Ali hydrometric station located at the outlet of the Alshar River from 1970 to 2018. For analysis, 11 water quality variables were selected. Man-Kendall test was used to examine the trend of changes. The results showed that the patterns were similar for changes in parameters at both annual and seasonal scales, with decreasing concentrations of HCO3, Na, pH and SAR and increasing concentrations of Mg, Ca, TH, TDS, EC, Cl, and SO4. In the annual period, the trend of change of all qualitative parameters except Na was statistically significant at 99% level. During the summer seasons, there were more intense upward and slower downward trends, with the strongest increase in concentration during this season. However, in the winter, the results were in contrary with the summer. In most of the qualitative parameters, the decreasing and increasing trends were higher in spring than in autumn. The reason for this could be attributed to the fact that winter snow melting from the altitudes occurs in the spring, causing increased surface currents and a relative decrease in concentrations.

کلیدواژه‌ها [English]

  • Aleshtar
  • Man-Kendall
  • Quality
  • River
  • Trend
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