چکیده:
رودخانهها در طول زمان با تغییرات مورفولوژیکی و اکولوژیکی زیادی مواجهاند و این در برنامهریزیهای محیطی و عمرانی حائز اهمیت است. طالقانرود در استان البرز ازجمله رودخانههایی است که طی سالهای اخیر به دلایلی مانند سدسازی، تغییرات کاربری اراضی در اثر توسعه کشاورزی، ساختوسازها، گردشگری و برداشت شن و ماسه، تغییرات زیادی داشته است؛ بنابراین پژوهش حاضر به بررسی تغییرات طبیعی و انسانی مؤثر در وضعیت هیدرومورفولوژیکی طالقانرود و اقدامات مدیریتی مقتضی میپردازد. دادههای مورداستفاده در تحقیق شامل اطلاعات کتابخانهای، اطلاعات بهدستآمده از تصاویر گوگل ارث و بازدیدهای میدانی و همچنین مدل رقومی ارتفاعی 5/12 متر است. ابزارهای تحقیق شامل نرمافزارهای ArcGIS و گوگل ارث و همچنین مدلهای RQI و MQI بوده است. این تحقیق در دو مرحله کلی انجامشده است. در مرحله اول با استفاده از روش RQI شرایط محیطی در بازههای موردمطالعه ارزیابی شد. در مرحله دوم نیز با استفاده از مدل MQI، وضعیت دینامیک رودخانه بررسی گردید. نتایج بهدستآمده از روش RQI نشان میدهد که بازههای 1 تا 6 که در بالادست سد قرار دارند، دارای وضعیت فقیر بوده و ازنظر مدیریتی نیازمند بازسازی سیستمهای پوششگیاهی است و بازههای 7 و 8 نیز در محدوده سد طالقان و پاییندست، دارای وضعیتی متوسط هستند که لازم است تا اقدامات حفاظتی در مورد آنها اجرا شود. همچنین نتایج حاصل از ارزیابی وضعیت مورفولوژیکی رودخانه بیانگر آن است که مناطق بالادست؛ یعنی بازههای 1 تا 5 به علت ضعیف شدن فرایندهای فرسایشی ناشی از تغییرات سطح اساس، دارای وضعیت پویایی مورفولوژیکی خیلی ضعیف و بازه 6 که در محدوده ورودی سد قرار دارد ازنظر شاخص MQI دارای وضعیت دینامیک ضعیف است. بازههای 7 و 8 به دلیل تغییرات کمتر، دارای بالاترین ضریب هستند و ازنظر دینامیک ژئومورفولوژی، پویایی بیشتری نسبت به سایر بازهها دارند.
Rivers face many morphological and ecological changes over time, and these changes are important in environmental and development planning. The Taleghan River in Alborz Province is one of the rivers associated with many morphological and ecological changes in recent years, and for this reason, this issue has been addressed in this study. The data used in the research included library information, information obtained from Google Earth images, information obtained from field visits, as well as the 12.5 SRTM digital elevation model. Research tools also included ArcGIS and Google Earth software, as well as RQI (description and assessment of environmental conditions in riverine areas) and MQI (morphological quality index) models. This research has been carried out in two general stages. In the first stage, the environmental conditions of the studied periods have been evaluated using the RQI method, and in the second stage, the river dynamics of the periods has been investigated using the MQI model. The results obtained from RQI method have shown that intervals 1, 2, 3, 4, 5 and 6 with 46, 67, 69, 64, 44 and 43 points, respectively, have a poor status and intervals 7 and 8 They also have an average position with 74 and 76 points, respectively. Also, the results of the evaluation of the dynamic condition of the river have shown that intervals 1, 2, 3, 4 and 5 with coefficients of 0.188, 0.156, 0.156, 0.117 and 0.242, respectively. Very poor morphological dynamics, interval 6 with a coefficient of 0.453 in terms of MQI index has a weak dynamic state and also intervals 7 and 8 with a coefficient of 0.477, have the highest coefficient and in terms of geomorphological dynamics have more dynamics than the other intervals. Extended Abstract 1-Introduction Rivers are dynamic systems. They change over time under the influence of various factors such as human activities. Morphological and ecological changes in rivers are important for environmental planning and development because these changes cause changes in the amount of sediment, and erosion of banks and facilities near the riverbed. In recent years, rivers have faced many morphological and ecological changes due to the lack of proper management. Human activities such as urban development, agriculture, industry, etc. have caused the physical and chemical characteristics of rivers to change and affect the ecological status of the river. Human impacts on the river without the necessary information will be associated with ecological and morphological changes in the river. Humans directly and indirectly affect processes and accelerate natural change in the river. The most important cases in this regard are the improper use of water resources, agricultural and industrial development, dam construction that causes severe evaporation of water and more sedimentation in rivers, limiting the river channel in long distances, creating multiple bridges with foundations inside the river and pouring municipal and industrial effluents and pointed. The importance of the river issue, especially ecological changes and the morphological dynamics of rivers has led to be addressed in this study. In this paper, using RQI and MQI models, the ecological status and morphology of Taleghan River is evaluated. 2-Materials and Methods In this study, quantitative and qualitative methods are applied. The data included library resources, information obtained from Google Earth images, data obtained from field visits, and a 12.5-meter Alsopalsar digital elevation model. Research tools included ArcGIS and Google Earth software, as well as RQI (River Quality Index) and MQI (Morphological Quality Index) models. In this study, in order to study the river in the study area, first, based on natural characteristics, the river in question is divided into 8 sections. This research has been carried out in two general stages. In the first stage, using the RQI method and based on quantitative and qualitative information obtained from field visits and satellite images, the environmental conditions of the eight sections have been evaluated. In the second stage, using the MQI model, the dynamics of the river of intervals is investigated. 3- Results and Discussion In this study, to investigate the ecological status and morphological dynamics of Taleghan River based on the natural characteristics of the area, 8 homogeneous sections have been selected and then based on the indicators in RQI and MQI methods, these intervals have been evaluated. Examination of the morphological conditions of the sections indicates that section 1 is located in the mountain unit and has a high limit, but sections 2 to 8 are located in the flood plain unit and have less restriction than section 1. The RQI index indicates that sections 1, 2, 3, 4, 5, and 6, with scores of 46, 67, 69, 64, 44, and 43, respectively, are poor and in need of vegetation regeneration systems. Sections 7 and 8, with 74 and 76 points, respectively, are in average condition and need management measures to improve hydrological and ecological conditions. The results of the evaluation also show that sections 1, 2, 3, 4 and 5 with coefficients of 0.188, 0.156, 0.156, 0.117 and 0.242 have dynamic status, respectively. Morphologically they are very weak. In these sections, there is little dynamics and dynamics of morphology due to narrowing and less involvement of human factors. Sections 7 and 8 with a value of 0.477 have the highest coefficient and have a more dynamic morphology than other sections. Interval 6 with a coefficient of 0.453 for the MQI index has a weak dynamic state. 4- Conclusion The results show that Section 1 is poor in terms of vegetation; also associated with low morphological dynamics because of locating in a high and steep area. But sections 7 and 8 have moderate vegetation because they are located in an area with low altitude and slope. Low slope and the involvement of human factors in these sectors has caused a higher coefficient to be calculated dynamically than other sectors. Accordingly, sections 7 and 8 have a better ecological status than other sections. However, they are subject to changes due to river dynamics and human activities, and it is necessary to take effective management measures in these two areas.
خلاصه ماشینی:
فعاليت هاي انساني شامل صنعتي شدن شهرها، کشاورزي، صنايع و غيره سبب تغييـر کيفيت فيزيکي و شيميايي آب رودخانه ها شده و وضعيت اکولوژيکي رودخانه را تحت تأثير خود قرار داده است ( ,Bussettini ٢٠١٣ ؛ جداري عيوضي و همکاران ، ١٣٨٩).
به دليل اهميت تغييرات ژئومورفيک در رودخانه ها تحقيقات زيادي به اين موضوع پرداخته اند ازجمله ميتوان به نمونه هايي مانند هيدرو مورفولوژي رودخانه لاويـج بـا اسـتفاده از شاخص هاي کيفيت ژئومورفولوژي (اسماعيلي و ولي خاني، ١٣٩٣)، تغييرات مورفومتري پيچان رودها (جوکار سرهنگي و همکاران ، ١٣٩٦)، پيامدهاي زيست محيطي ناشي از طرح هاي توسعه منابع آب تحت تأثير تغييرات مورفولوژي رودخانۀ کرج (صمدي و عزيزيان ، ١٣٩٦: ٨٦)، تحول مورفولوژيکي الگوي رودخانه با شاخص هاي هندسي در آزاد رود (رضايي مقدم و همکاران ، ١٣٩٦)، ارزيابي جريان زيست محيطي رودخانه با روش اکوهيدرولوژي در مهاباد چاي (رزاقي رضائيه ، ١٣٩٧).
Pascacio et al ؛٢٠١١ ,De Jalon &Del Tanago ) شاخص وضعيت اکولوژيکي امتياز عرض متوسط کريدور پوشش گياهي به شدت کاهش يافته و يا به دليل اقدامات انساني وجود ندارد.
شاخص F٧ بر تغيير الگوي رودخانه ناشي از دخالت انسان تأکيد دارد و به دليل فقدان تغييرات محسوس در بازه هاي ٢، ٣ و ٤، به اين بازه هاي امتياز صفر و به ساير بازه ها به دليل داشتن تغييرات امتياز ٣ داده شده است .
شاخص F١١ بر وجود چوب هاي بزرگ در کانال رودخانه تأکيد دارد و به تمامي بازه ها امتياز ٣ داده شده است .