شناسایی مناطق کارست آسیبپذیر با استفاده از مدل COP (مطالعه موردی: حوزه آبریز تکاب) (مقاله علمی وزارت علوم)
درجه علمی: نشریه علمی (وزارت علوم)
آرشیو
چکیده
مناطق کارستیک به دلیل نقش مهمی که در تأمین منابع آب لازم دارند، بسیار حائز اهمیت هستند. یکی از مسائل مهم مناطق کارستیک پتانسیل بالای آلودگی این منابع است. با توجه به اهمیت موضوع، در این پژوهش مناطق مستعد آلودگی در حوزه آبریز تکاب شناسایی شده است. در پژوهش حاضر برای دستیابی به هدف های مدنظر از نقشه های توپوگرافی ۱:۵۰۰۰۰، نقشه زمین شناسی ۱:۱۰۰۰۰۰، مدل رقومی ارتفاعی 5/12 متر و تصاویر ماهواره لندست به عنوان داده های پژوهش استفاده شد. ابزارهای مهم استفاده شده در این مطالعه شامل ArcGIS و ENVI است. این پژوهش در دو مرحله کلی انجام شده است. در مرحله اول با استفاده از روش COP مناطق آسیب پذیر در برابر آلودگی شناسایی و در مرحله دوم نیز روند توسعه نواحی سکونتگاهی به سمت این مناطق شناسایی شد. بر اساس نتایج مدل COP حدود 33 درصد از منطقه که بیشتر شامل مناطق شمال غربی و جنوبی حوضه است، به دلیل نوع لیتولوژی، نوع پوشش زمین، وضعیت هیدرواقلیمی و وضعیت ژئومورفولوژی پتانسیل آسیب پذیری زیاد و خیلی زیادی دارند. همچنین، نتایج حاصل شده از ارزیابی روند تغییرات کاربری اراضی بیانگر این است که کاربری نواحی انسان ساخت در سال 1990 حدود 8 کیلومتر مربع بوده که این میزان در سال 2019 به حدود 19 کیلومتر مربع افزایش یافته است. با توجه به موارد مذکور بخش های جنوبی و شمال غربی حوزه آبریز تکاب به دلیل روند توسعه نواحی انسان ساخت پتانسیل آسیب پذیری زیادی در برابر آلودگی دارند.Identification of Vulnerable Karst Areas Using the COP Model (Case Study: Tekab Basin)
Karst landscapes are of great importance due to their role in providing vital water resources. However, these areas face a high risk of resource pollution, which is a significant concern. This study aimed to identify pollution-prone zones within the Tekab Catchment. The research utilized topographic maps (1:50,000 scale), a 1:100,000 geological map, and a 12.5-m digital elevation model derived from Landsat satellite imagery. Key analytical tools included ArcGIS and ENVI software. The study was conducted in two stages. First, the (Concentration, Overlapping, and Protection (COP) method was employed to delineate areas vulnerable to pollution. Second, the trend of residential expansion towards these vulnerable zones was assessed. The COP model results indicated that approximately 33% of the catchment area, primarily the northwestern and southern regions, exhibited high to very high pollution vulnerability. This was attributed to the underlying lithology, land cover type, hydroclimatic conditions, and geomorphological characteristics. Furthermore, evaluation of land use changes revealed that the built-up area had increased from 8 km2 in 1990 to 19 km2in 2019. Consequently, the southern and northwestern parts of the Tekab Catchment were facing heightened vulnerability due to both their inherent pollution potential and the ongoing expansion of human settlements. These findings underscored the critical need for targeted management strategies to protect the valuable water resources within the Tekab Catchment, particularly in the identified high-risk zones, and ensure the long-term sustainability of this important karst landscape. Keywords: Pollution, Landuse Changes, Karst Areas, COP. IntroductionKarst landscapes are characterized by the dissolution of bedrock and the formation of an intricate underground drainage network predominantly associated with carbonate rock formations. Karst springs are of crucial importance as they supply drinking water to approximately 25% of the global population. Considering the significant role of karst resources in providing water, protection of these valuable resources is essential. Karst landscapes are highly vulnerable and sensitive to pollution, which poses a significant challenge in the management of karst water resources. Iran's geographical location has led to approximately 11% of the country's area being covered by karst formations, including the Tekab Catchment located in the northwest of the country. The hydro-climatic characteristics of the Tekab Basin have contributed to the high potential for karst resource development, making the protection and prevention of pollution in these resources a pressing priority. Given the importance of karst water resources and the need for their protection, this study aimed to identify the areas within the Tekab Catchment, which were prone to pollution. Understanding the vulnerability of the basin to pollution is a crucial step in developing effective management strategies to safeguard these vital water resources. Materials and MethodsThis study utilized a range of geospatial data and analytical tools to achieve its objectives. The research data included 1:50,000 scale topographic maps, a 1:100,000 geological map, and a 12.5-m digital elevation model derived from Landsat satellite imagery. The key software tools employed were ArcGIS and ENVI, which were used to prepare the necessary maps and land use datasets. The research methodology was divided into two main stages. In the first stage, the Concentration, Overlapping, and Protection (COP) method was applied to identify areas within the study area that were vulnerable to pollution. This approach primarily examined two factors: the travel time of pollutants from the source to the destination and the reduction in pollutant concentration along the flow path. In the second stage, land use maps were generated for the years 1990 and 2020 using Landsat satellite imagery. This allowed for the assessment of the development trends of anthropogenic land uses (e.g., settlements) in relation to the previously identified vulnerable areas. By integrating the results from these two stages, the study was able to delineate the zones within the Tekab Catchment that were susceptible to pollution and analyze the spatial patterns of human-induced land use changes that might exacerbate the vulnerability of these critical water resources. Research FindingsThe COP method was employed to assess the vulnerability of the study area. The C factor represented the infiltration capacity, emphasizing the permeability and influence of precipitation on the ground surface. According to the C factor map, the northern parts of the region exhibited the highest potential for vulnerability. The O factor was calculated based on soil properties, including permeability, thickness, porosity, and lithological composition. This analysis indicated that the southern and northwestern regions of the basin had the greatest potential for vulnerability. The P factor considered the characteristics of precipitation, such as the amount, temporal distribution, duration, and intensity of floods, which could influence the infiltration rate. Based on this factor, the eastern and northern parts of the basin were identified as the most vulnerable areas. By integrating the maps of the individual factors, the overall vulnerability map was generated using the COP method. The results revealed that the southern and northwestern regions of the study area had the highest vulnerability to pollution. Additionally, this study examined the trend of land use development, specifically the expansion of anthropogenic land uses (e.g., settlements) towards the vulnerable areas. The analysis showed a significant increase in human-induced land uses within the vulnerable zones over a 30-year period. Discussion of Results & ConclusionThe Tekab Catchment area is characterized by a distinct karst landscape, shaped by the region's underlying lithology and hydro-climatic conditions. This makes the identification and protection of vulnerable karst resources a critical priority. While numerous studies have focused on assessing the vulnerability of karst areas, this research presented a unique approach by not only delineating the vulnerable zones, but also analyzing the development of anthropogenic land uses within these sensitive areas. The evaluation of the COP model in the Tekab Catchment revealed that the southern and northwestern regions of the basin exhibited high to very high vulnerability. This could be attributed to the specific lithological characteristics, land cover types, hydro-climatic factors, and geomorphological conditions prevalent in these areas. Furthermore, the analysis of land use change over a 30-year period (1990 to 2019) showed a significant increase in the expansion of human-induced land uses, such as settlements, within the identified vulnerable zones. The areal extent of these anthropogenic land uses had increased from approximately 8 km2 in 1990 to nearly 19 km2in 2019. Given the high vulnerability of the southern and northwestern parts of the Tekab Catchment coupled with the intensifying development of human activities in these sensitive areas, it is crucial to implement targeted planning and management strategies. This should involve prevention of polluting industries and activities from encroaching into these vulnerable zones in order to safeguard the critical karst water resources that serve the local population.
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