ارزیابی ریسک محیط‌زیستی سد جیرفت در مرحله‌ بهره‌برداری

سدها ازنظر اقتصادی، سیاسی و اجتماعی سازه‌هایی بسیار مهم به شمار می‌آیند و نقش آنها در توسعه‌ کشورها انکارناپذیر است. از سوی دیگر، سدها سازه‌هایی با خطر پیش‌رونده محسوب می‌شوند؛ بنابراین با توجه به اهمیت راهبردی آنها، لازم است بتوان به‌‌طور دقیق ریسک‌‌هایی را شناسایی کرد که این سازه‌‌ها ایجاد می‌کنند. سد جیرفت، یکی از مهم‌ترین سدهای بتنی دو قوسی در جنوب استان کرمان روی رودخانه‌ هلیل‌رود است که وظیفه‌ تامین نیاز آبی بخش‌های مختلف را بر عهده دارد. هدف از پژوهش حاضر، شناسایی و ارزیابی ریسک سد جیرفت در فاز بهره‌برداری با استفاده از روش efmea است. بدین منظور ریسک‌های مدنظر در پنج گروه محیط فیزیکی‌شیمیایی، طبیعی، بیولوژیکی، محیط اجتماعی، اقتصادی و فرهنگی و ایمنی و بهداشتی طبقه‌بندی شدند و سپس با مصاحبه با کارشناسان و متخصصان خبره درباره‌ سد جیرفت کاربرگ ارزیابی ریسک براساس احتمال وقوع، شدت اثر و احتمال کشف تکمیل شد. در این روش امتیازدهی به هریک از ریسک‌های احتمالی در محیط‌های پذیرنده صورت گرفت. با مشخص‌شدن احتمال وقوع، شدت و احتمال کشف، مقدار عددی اولویت هر ریسک (rpn) محاسبه شد و درنهایت به‌منظور تعیین اولویت سطح ریسک، حد بالا و پایین ریسک، مقادیر میانگین و انحراف معیار با استفاده از نرم‌افزار spss به دست آمد. نتایج این پژوهش نشان داد در گروه ریسک‌های مربوط به محیط فیزیکی‌شیمیایی فرسایش خاک و رسوب‌گذاری، در محیط بیولوژیکی ریسک اثرگذاری بر زیستگاه و تهدید حیات آبزیان در پایین‌دست، در گروه ریسک‌های ایمنی و بهداشتی خطاها و اشتباهات انسانی، قبل، بعد و حین بهره‌برداری، سطح ریسک بالا را به خود اختصاص داده‌اند. با تکیه بر نتایج پژوهش و با برنامه‌ریزی درست و ارائه‌ راهکارهای پیشگیرانه و اصلاحی، می‌توان خطرات محیط‌زیستی ناشی از سد را به میزان زیادی کاهش داد.

Evaluation of the Environmental Risks of Jiroft Dam During the Utilization Phase

Extended abstract:IntroductionDams are economically, politically, and socially important structures and their roles in the development of countries are undeniable. The purpose of this study was to investigate the environmental risks of Jiroft Dam in the utilization phase so as to reduce its negative effects. Construction of a large dam can threat the environment in various ways. In this research, the physicochemical, natural, biological, socioeconomic and cultural, and safety and health risks of Jiroft Dam were evaluated. MethodologyIn this study, EFMEA method was used to assess the environmental risks of Jiroft Dam. To evaluate the relevant risks, 29 parameters in 5 groups, including physicochemical, natural, socioeconomic and cultural, biological, and safety and health risks were chosen. The data were collected by interviewing the experts. The risk factors were evaluated by using EFMEA method based on the probability of occurrence and severity and probability of detection. To determine priorities of the risk levels, the upper and lower limits of each risk and its average and standard deviation were obtained. DiscussionBased on the Risk Priority Number (RPN), the soil erosion with RPN=100 and in river downstream morphology changes with RPN=12 showed the highest and lowest risk values related to the physicochemical factors. Also, flood with RPN=60 and landslide with RPN=20 displayed the highest and lowest risk values related to the natural risk factors. Moreover, among the biological risk factors, the impacts on the habitat (RPN=75) and threats to the aquatic life of the downstream (RPN=80) demonstrated the highest numerical risk values. The lowest RPN was related to propagation of weeds in the downstream of the dam and changes in food chains (RPN=20). Also, landuse change (RPN=20) and social acceptance and security risks (RPN=6) revealed the highest and lowest risk levels related to the social, economic, and cultural factors. Furthermore, human mistakes before, during, and after the utilization phase, which were related to the safety (RPN=75) and health (RPN=48) risk factors depicted the highest levels of risk, while the growth of insects in Jiroft Dam Reservoir (RPN=12) indicated the lowest risk value. ConclusionAccording to the findings, soil erosion and sedimentation showed highrisk levels in the group of physicochemical risks. Moreover, their effects on water sources (thermal layering), pollution (air, sound, soil, and water), downstreamsuspended solids, soil eutrophication, and soil compaction were classified in a moderaterisk class, while the river morphology change was classified in the lowrisk class. The earthquake, flood, and landslide were classified in the moderaterisk class. Also, the habitat risk and threatening to the aquatic life of the downstream related to the biological risks were classified in the highrisk class. Effects on the vegetation, blocking of the migration route (animal movement), propagation of weeds in downstream of the dam, changes to the food chains, and degradation of harbor area were classified in the moderaterisk class. Among the socioeconomic and cultural indices, the land use change as well as the reduced employment and income in the region were classified in the mediumrisk class, while the social acceptance and security, tourism acceptance, and land acquisition were classified in the lowrisk class. In the group of safety and health risks, human mistakes before, during, and after the utilization phase showed a high risk, while creating a suitable environment for the growth of insects in Jiroft Dam Reservoir displayed a lowrisk level. The risks of explosions, war, and terrorism related to the dam, corrosion of facilities, and spread of diseases were classified in the moderaterisk class. 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