ارتباط پارامترهای کمّی و کیفی آب های زیرزمینی با ویژگی های مخروط افکنه های دشت های جنوبی البرز مرکزی (کرج تا تاکستان) (مقاله علمی وزارت علوم)
درجه علمی: نشریه علمی (وزارت علوم)
آرشیو
چکیده
آب زیرزمینی به عنوان جزئی از یک سیستم تعاملی با سطح زمین در قلمرو تأثیرپذیری ژئومورفولوژی قرار دارد و به میزان زیادی تحت تأثیر و کنترل لند فرم ها و فرآیندها است و می تواند بر میزان کمیت و کیفیت آب زیرزمینی اثر بگذارد. یکی از لند فرم های مهم ژئومورفولوژی مناطق خشک و نیمه خشک ایران مخروط افکنه هاست که محیط بسیار مناسبی را برای ذخیره سازی آب زیرزمینی فراهم می آورد. در این پژوهش سعی شده به تحلیل ارتباط تغییرات کمی و کیفی آب های زیرزمینی با ویژگی های مخروط افکنه ها در دشت های جنوبی البرز مرکزی پرداخته شود، تا از این طریق بتوان روشی مناسب و مبتنی بر پارامترهای ژئومورفیک را برای پتانسیل یابی کمی و کیفی آب های زیرزمینی ارائه داد. بر این اساس به وسیله تصاویر ماهواره ای و نقشه های توپوگرافی ابتدا مرز 23 مخروط افکنه ترسیم و 11 پارامتر مورفومتری شامل زاویه جاروب، مساحت، حجم، تقعر، شیب، ارتفاع رأس و قاعده، طول، طول قاعده، شعاع و اختلاف ارتفاع مخروط افکنه استخراج گردید. همچنین ارتباط عمق سطح ایستابی، دبی آب چاه و میزان هدایت الکتریکی آب زیرزمینی با پارامترهای مورفومتری در 587حلقه چاه آب با استفاده از تحلیل های آماری مورد ارزیابی قرار گرفت. نتایج نشان داد تغییرات دبی، هدایت الکتریکی و عمق سطح ایستابی به ترتیب با میزان 63%، 27 % و 54% تحت تأثیر مورفومتری مخروط افکنه ها قرار دارد. با افزایش میزان مساحت، طول، شعاع و طول قاعده مخروط افکنه ها میزان دبی آب چاه ها افزایش پیدا می کند و با افزایش حجم و تقعر میزان هدایت الکتریکی نیز افزایش می یابد. یافته های این پژوهش نشان داد ویژگی مخروط افکنه ها می تواند به عنوان روشی در ارزیابی تغییرات کمی و کیفی آب های زیرزمینی در مناطق خشک مورداستفاده قرار گیرد.The Relationship Between Quantitative and Qualitative Networks of Groundwater with the Characteristics of Alluvial fan in The Southern Hillside of Alborz center (Karaj to Takestan)
Extended Abstract
Introduction
Groundwater is considered one of the most important indicators of environmental development, and land planners pay great attention to identifying the quantitative and qualitative status of these resources. In general, the sustainable management of groundwater resources during crises can reduce the effects of drought and water shortages. This issue is particularly significant in the central plains of Iran, where water scarcity and low rainfall are prevalent. Therefore, to manage these resources effectively, it is crucial to identify the factors that influence them. In recent years, increased attention has been paid to landforms and environmental indicators as parameters affecting the permeability and variability of groundwater. Over the past decade, there has been a notable increase in studies and articles in this field.
Among the key landforms in the geomorphology of arid and semi-arid regions of Iran are alluvial fans. Due to their unique structure, these fans provide an ideal environment for groundwater storage. This research focuses on the southern slopes of the central Alborz mountains to develop a model based on geomorphic parameters for assessing the quantitative and qualitative potential of groundwater. The findings of this study present innovative approaches to utilizing landforms in identifying areas with suitable groundwater potential.
Material and Methods
The alluvial fans located in the southern slopes of the central Alborz hills cover a significant part of the western plains of Tehran Province, as well as the southern plains of Alborz and Qazvin provinces. The total area of this region is 7,450 square kilometers, and it is part of the sub-basins of the Salt Lake system.
In this research, the morphometric characteristics of 23 alluvial fans in the southern plains of central Alborz were analyzed using correlational research and ex-post facto methods. With a practical approach, the boundaries of the alluvial fans were delineated using satellite images and topographic maps. Eleven morphometric parameters, including sweep angle, area, volume, concavity, slope, apex and base height, length, base length, radius, and height difference of the alluvial fans, were extracted.
Additionally, the relationships between water table depth, well discharge, and electrical conductivity (EC) of groundwater with morphometric parameters were evaluated using statistical analysis of 587 water wells.
Results and Discussion
The results showed that changes in discharge, EC, and water table depth were influenced by the morphometry of the alluvial fans, with contributions of 63%, 27%, and 54%, respectively. Furthermore, the results revealed that among the 11 morphometric parameters, increases in the average values of four parameters—area, cone length, base length, and radius of the alluvial fan—led to higher groundwater extraction potential. Conversely, decreases in apex height, sweep angle, and base height corresponded to increases in flow rates.
The findings indicated that in alluvial fans where the apex and base elevations are higher than others, the water table is lower relative to ground level due to increased sedimentation and sediment thickness. Moreover, the depth of the water table increases with the enlargement of the area, length, base length, and radius of the alluvial fans. Alluvial fans with large, circular, fan-shaped structures exhibited higher levels of groundwater stagnation.
ConclusionReducing concavity or sediment diameter on the surface of alluvial fans can effectively decrease soil refinement during water infiltration. This study highlights that examining geomorphic landforms prior to implementing water resource management plans can The analysis of groundwater electrical conductivity (EC) demonstrated that EC values increased in alluvial fans with high sediment volume and low concavity.significantly reduce errors in selecting locations for aquifer recharge or groundwater well excavation.
This research, through its innovative approach and robust statistical analysis, has introduced a new model to evaluate the role of alluvial fans in the quantitative and qualitative changes in groundwater. The findings offer an efficient and effective framework for identifying groundwater table potentials, providing valuable insights for sustainable water resource management.
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