شناسایی و تحلیل پهنه‌های در معرض مخاطره سیل در سکونتگاه غیررسمی نایسر ـ شهر سنندج
محورهای موضوعی : برنامه ریزی محیطی
ایوب محمدی
1
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داود جمینی
2
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رامین آتش بهار
3
1 - عضو هیئت علمی دانشگاه کردستان
2 - استادیار گروه ژئومورفولوژی، دانشکده منابع طبیعی، دانشگاه کردستان، سنندج، ایران (پژوهشگر پاره وقت پژوهشکده کردستان شناسی، دانشگاه کردستان).
3 - گروه ژئومورفولوژی، دانشکده منابع طبیعی، دانشگاه کردستان، سنندج، ایران.
کلید واژه: مخاطرات محیطی, سیل, پهنه های سیل گیر, سکونتگاه های غیررسمی.,
چکیده مقاله :
سکونتگاه¬های غیررسمی با چالش¬هایی نظیر رشد فزاینده جمعیت، فقر، بیکاری، ناهنجاری اجتماعی، مسکن ناپایدار، ضعف شدید زیرساخت¬های ضروری و ... گره خورده است. این چالش¬ها در صورت عدم توجه به مخاطرات طبیعی از جمله سیل که خسارات جانی و مالی متعددی را به همراه دارد، به شدت تشدید می¬گردد. نایسر به عنوان بزرگترین سکونتگاه غیررسمی استان کردستان در حال حاضر با چالش¬های متعددی نظیر ضعف شدید امکانات خدماتی و رفاهی ضروری، فقر، مصرف مواد مخدر، فقر، بیکاری و ... مواجه است. در صورت وقوع سیل در این فضای پرتراکم شهری، خسارات ناشی از آن می¬تواند آسیب‌های جبران ناپذیری را بر ساکنان و محیط شهری آن تحمیل نماید. از این¬رو هدف اصلی پژوهش کاربردی حاضر که با روش توصیفی ـ تحلیلی انجام گرفته است، شناسایی پهنه¬های در معرض مخاطره سیل در نایسر به‌عنوان یک سکونتگاه غیررسمی با استفاده از 17 معیار کلیدی است. برای تهیه لایه¬های مورد استفاده از سایت گوگل ارث انجین، نرم افزار Arc Map و سایر دیتابیس¬های موجود استفاده شده است. همچنین با استفاده از تصاویر راداری سنتینل ـ1، 100 پهنه سیلابی در نایسر استخراج شده است. برای وزن دهی به معیارهای اصلی پژوهش از نظرات 15 نفر از کارشناسان و محققان استفاده شده و برای تهیه نقشه پهنه¬بندی نهایی از روش Fuzzy Overlay و تابع Sum استفاده گردیده است. نتایج پژوهش نشان داد سه لایه شیب، فاصله از رودخانه و تراکم رودخانه به¬ترتیب با مقادیر 1345/0، 1032/0 و 0928/0، بیشترین وزن را به خود اختصاص داده¬اند. یافته¬های حاصل از پهنه¬بندی نایسر به لحاظ سیل¬گیر بودن نشان داد 01/98 هکتار (47/30 درصد) در پهنه¬های با خطر بسیار کم و کم، 56/81 هکتار (36/25 درصد) در پهنه خطر متوسط و 04/142 هکتار (16/44 درصد) در پهنه¬های خطر زیاد و بسیار زیاد قرار گرفته است.
Informal settlements are tied to challenges such as increasing population growth, poverty, unemployment, social anomaly, unstable housing, severe weakness of essential infrastructure, etc. These challenges are greatly aggravated if we do not pay attention to natural hazards, such as floods, which cause many human and financial losses. As the largest informal settlement in Kurdistan province, Naysar is currently facing many challenges such as the severe lack of essential services and welfare facilities, poverty, drug use, poverty, unemployment, etc. If a flood occurs in this dense urban space, the resulting damages can cause irreparable damage to the residents and its urban environment. Therefore, the main goal of the present applied research, which was carried out with descriptive-analytical method, is to identify areas exposed to flood risk in Naysar as an informal settlement using 17 key criteria. Google Earth Engine website, Arc Map software and other available databases have been used to prepare the examined layers. Also, using Sentinel-1 radar images, 100 flood zones in Naysar have been extracted. The opinions of 15 experts and researchers were used to weight the main criteria of the research, and the Fuzzy Overlay method and the Sum function were used to prepare the final zoning map. The results of the research showed that the three layers of slope, distance from the river and density of the river have the most weight with the values of 0.1345, 0.1032 and 0.0928 respectively. The results of Naysar zoning showed that 98.01 hectares (30.47 percent) are located in very low and low risk zones, 81.56 hectares (25.36 percent) are in medium risk zones and 142.04 hectares (44.16 percent) in high and very high-risk zoning.
Extended Abstract
Introduction
In order to manage flood risk and reduce its damages, the time of flood occurrence can be monitored correctly by using modern technologies and information systems. Meanwhile, for an effective response during floods, quick monitoring of flood-prone areas through zoning different geographic areas is very vital to reduce damages. Various methods and indicators have been used for zoning and accurate modeling of flood risk. Meanwhile, relying on approaches based on remote sensing and geographic information system is a low-cost tool that can be profitably used for flood zoning. By identifying flood-prone areas, the damage caused by floods can be greatly reduced in different parts. For this reason, the preparation of flood risk zoning maps for the bodies and organizations responsible for its management is one of the basic requirements. Because thanks to it, they can deploy their equipment and facilities for quick response in high-risk places and reduce the damages caused by floods. Considering the harmful financial, human, and environmental effects of flood risk, it is very important to identify flood-prone areas in order to manage this risk. Because through it, while identifying the residential and non-residential spaces that are at risk of flooding, it is also possible to identify high-risk spaces and through it, it is possible to prevent construction in these high-risk spaces. According to the mentioned contents, the basic problem of the current research is: What is the distribution of flood zones in Naysar? and how much of the area of Naysar is located in areas with high risk of flooding?
Methodology
Based on the divisions made regarding the research method, the present research is in the applied research group in terms of the purpose and the method used, which was carried out using the descriptive-analytical method. In order to achieve the main goal of the research, various steps have been taken, which have been described in a systematic process. In this way, first by reviewing the sources related to the subject under study, effective factors related to flood zoning (17 layers) have been identified. In the following, layers have been prepared using related sites and software. After extracting the 17 layers using the tools available in the Arc Map software, necessary processing has been done on the layers. At this stage, using the opinions of researchers, experts and previous studies, weighting has been done to the classes of each layer. According to the nature of the fuzzy theory, the weight of the layers is between 0 and 1, in which the number 1 has the highest value and 0 the lowest value. In the following, to prepare the final zone of flooded areas in the studied area, the opinions of researchers and experts have been used to weigh the criteria used. It should be noted that the opinions of 15 people were used to weight the criteria, and the fuzzy overlay method and the Sum function were used to prepare the final zoning map.
Results and discussion
The results of the research showed that the three layers of slope, distance from the river and density of the river have the most weight with the values of 0.1345, 0.1032 and 0.0928 respectively. The results of Naysar zoning showed that 98.01 hectares (30.47 percent) are located in very low and low risk zones, 81.56 hectares (25.36 percent) are in medium risk zones and 142.04 hectares (44.16 percent) in high and very high-risk zoning.
Conclusion
Informal settlements face many challenges and issues by nature and are often at an inappropriate level in terms of having other objective and subjective criteria of development. Citizens living in these unstable spaces can be considered among the most vulnerable sections of the society. Despite the numerous restrictions and exclusions of citizens living in informal settlements, in the event of natural disasters, the damage caused by these disasters can be the basis of serious crises in these residential spaces. Among natural disasters, flood is one of the most destructive and frequent hazards that can cause numerous financial and human damages. In fact, the occurrence of floods in informal settlements, which inherently face many challenges, can seriously threaten the livelihood of its residents. Naysar, as one of the largest informal settlements in western Iran, is not exempt from the above rule. Therefore, identifying areas at risk of flooding in Naysar can be an important step in the direction of crisis management in this urban space. The results of the research showed that about 70% of the investigated area in the informal settlement of Naysar is located in medium, high and very high-risk areas. This situation indicates the unfavorable condition of Naiser in terms of facing the risk of flooding. According to the results obtained in the direction of managing the flood crisis in Naysar, the following suggestions are presented: informing the citizens living in Naysar about areas at risk of flooding through mass media, social networks, etc.; Preventing construction and any activity in flood zones located in medium, high and very high risk classes; Equipping residential blocks, roads, etc. with surface water disposal system; Educating citizens on how to deal with floods; Construction of emergency medical and rescue centers in compliance with safety principles in the vicinity of dangerous areas; Stabilization of houses and facilities and equipment built in areas at risk.
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