پتانسیل‌سنجی خطر سیلاب شهری با رویکرد توسعۀ شهری ایمن (مطالعۀ موردی: شهر گنبد‌کاووس)

تغییرات آب‌وهوایی سیلاب را به‌همراه دارد. سیل می‌تواند نتیجۀ ریزش باران‌های شدید، ذوب سریع برف و یخ یا تخریب سدها باشد. این فرایند هر علتی که داشته باشد، وقتی که وارد مناطق شهری می‌شود موجب خسارات و گاهی کشته شدن افراد می‌شود؛ زیرا شهر در جریان رشد و توسعۀ خود، به فضاهای هیدرولوژیکی طبیعی تجاوز می‌کند. شهر گنبد در طی سنوات گذشته به‌ویژه در سیل‌ سال‌های 1371، 1380 و 1381 با تهدید سیلاب شهری مواجه بوده و نوع سیلاب، تلفیقی از رودخانه‌ای و ناگهانی بوده است. بی‌توجهی به تهدید شهر گنبد در اثر ریسک‌های سیلاب شهری سبب شده است که در این پژوهش، پتانسیل مخاطرات سیلاب شهری و سیل‌خیزی شهر گنبد بررسی شود. براساس ویژگی‌های سیل‌خیزی طبیعی و انسانی گنبدکاووس و با در نظر گرفتن تمامی جوانب دخیل در پتانسیل خطر سیل و ریسک در توسعۀ شهری به بررسی کاهش مخاطرات سیل برای شهر گنبد‌کاووس در قالب 54 عامل به‌روش تحلیل سلسله‌مراتبی ahp در یک جامعۀ متخصص 35 نفری متشکل از مقامات ارشد، مدیران کل و کارشناسان همۀ سازمان‌های مرتبط پرداخته شد. از میان سه معیار اصلی، معیار مطالعات و برنامه‌ریزی دستگاه‌های اجرایی با بیشترین وزن (0.75) مهم‌ترین تاثیر را در موضوع کاهش مخاطرۀ سیل شهری دارد. همچنین نقشۀ حاصل از خطرپذیری شهرستان گنبدکاووس که با استفاده از 9 پارامتر تعیین شد، بیانگر قرارگیری این شهر در پهنۀ با پتانسیل خطر زیاد است. نتایج حاصل و اتفاقات سیل اخیر حاکی از آسیب‌پذیری شهر گنبد ناشی از ریسک بیرونی سیلاب است. در سال‌های گذشته به ارتقای ایمنی شهر و پایین‌دست توجه نشده است و بر این اساس، باید مطالعات و برنامه‌ریزی جامع توسط دستگاه‌های اجرایی ذی‌ربط در نظر گرفته شود.

Evaluation of Urban Flood Risk Potential with Secure Urban Development Attitude (Case Study: GonbadeKavoos)

Flooding can be the result of severe rainfalls, melting snow or ice, or damaging dams. The GonbadeKavoos city has been threatened by urban floods over the past few years, in particular the floods of 1991, 2000 and 2001.Due to the lack of attention to the safety of the city after these hazards caused that this study has examined the potential of urban flood damage. Using a hierarchical analysis of AHP method and completing a questionnaire in an expert community of 35 people, we examined the flood risk factors in urban development. The results and its adaptation to the recent floods indicate the vulnerability of the city due to the several factors of external flood risk. For reducing these elements and Secure Urban Development, performing related studies and comprehensive planning by the relevant executive agencies on the agenda is necessaryIntroductionClimate change causes flood. When the flood enters the urban areas, it causes damage and sometimes the death of people, because when the city during its growth and development raises natural hydrologic spaces. When cities are exposed to floods or planning on flood plains, requires policies or programs for tackling floods. In the first step, programing for exposed city, flood facing and governing the adverse economic and social consequences requires the understanding the flood regime of the basins as well as a range of urban lands adjacent to each river that is in the potential risk of flooding. Thus for promoting city and lowering spaces safety, a model of urban development is needed. Materials and MethodsThe type of study and methodology is to examine hypotheses or answer questions, descriptive, empirical, content analysis, documentary and historical. The research methodology is descriptive and analytical based on field and library studies and map analysis which is a type of applied research. In this research, in order to assess the urban flood risk potential with and taking into account the factors involved in urban development in the form of studying the role of different organizations performance and the production of flood zoning map in a hierarchical analysis method, in a 35member specialist community was subjected to a pair comparison. A hierarchical analysis process can be considered when decisionmaking practice has multiple decision options.Discus and ResultsAfter analyzing the hierarchical analysis process among the three main criteria, the study and planning of the executive unit with a total inconsistency rate of 0.08 with a maximum weight of 0.75, has the most important role in the issue of flood risk reduction. Additionally by selecting 9 parameters of flood criteria in formation of vegetation cover, land use, elevation from the sea, slope, soil type, drainage density, river flood plain, rainfall and distance from the river, zoning map of hazard potentiality has been prepared and based on that, the city of Gonbad is located in high risk areas of the flood. Visiting the field and its adaptation to the flood of March 2019 of Gonbad city, confirming the compliance with the map of the potential hazard which has been produced. It considers the need of improving the city’s safety in relation to the risk of flood.ConclusionTherefore, due to the flood potentiality of the study area and the results obtained, it can be said that the studies and planning have been done so far related to flood risk  are insufficient. The need for integrated environmental studies and programing with integrated management in the form of urban development plans are necessary. It is the duty of the government to work hard on planning and implementing comprehensive flood management, attracting people’s participation with preventing unnecessary losses in cities in preserving the lives and properties of their inhabitants. Implementing these issues require a change of approach and attitude in the government and the other Forces. Renewed attitude of the High Council for Urban Architecture of Iran in the recent approvals dated 11.5.2109, confirming the results of the research and changing the government’s approach in this regard.