بررسی مهمترین مخاطرات محیطی در حوضه آبخیز شهر ایذه با استفاده از مدل‌های؛wlc و topsis

مخاطرات طبیعی نظیر سیلاب، زلزله و زمین لغزش جزء مهم ترین مخاطرات محیطی و به عنوان خطر بالقوه جدی برای توسعه فیزیکی شهرها محسوب می شوند. با توجه به توسعه شهرنشینی و تراکم بالای ساختمانی در شهر ، ریسک خسارت مالی و تلفات انسانی توسط سوانح طبیعی به طور چشم گیری بالا می رود. در این تحقیق بدلیل اهمیت مسائل ناشی از سیلاب، زمین لغزش و زلزله در توسعه فیزیکی شهر ایذه، ابتدا لایه های اطلاعاتی مختلف به عنوان فاکتورهای موثر در وقوع آن ها برای محدوده این شهر در محیط نرم افزارهای مرتبط تهیه شد. سپس اقدام به طبقه بندی و استاندارد سازی لایه ها بر اساس عضویت در تابع فازی گردید. در مرحله بعد آزمون عملیاتی با دو مدلtopsis و wlc از مدل های تصمیم گیری چند معیاری (mcdm) جهت پهنه بندی مخاطرات مذکور و مقایسه خروجی های حاصل از این روش ها به عمل آمد. نتایج ارزیابی مدل ها نشان داد که مخاطرات ناشی از زمین لغزش، سیل و زمین لرزه با مدل topsis به ترتیب 35 درصد، 33 درصد، 29 درصد و با مدل wlc، 22 درصد، 21 درصد، 38 درصد از منطقه را در بر می گیرند. این سطوح به عنوان مناطق با خطر بالا و بسیار بالا شناخته شدند. نتایج مقایسه ی مدل ها نشان داد که مدل wlc در زمینه پهنه بندی زمین لغزش و سیلاب نسبت به مدلtopsis ، پهنه هایی را نشان می دهد که به واقعیت نزدیک تر است. و مدل topsis مناسب ترین مدل در ارتباط با پهنه بندی خطر زمین لرزه در محدود مورد مطالعه تشخیص داده شد.

Evaluation of the environmental hazards in Watershed Izeh City using models; WLC and TOPSIS

Extended AbstractIntroductionNatural hazards such as floods, earthquakes and landslides as the main hazards and potentially serious threated to the physical development of the many city in the world. Izeh urban catchment area of 348/11 km square and is located in the East of the Khuzestan province. This region Climate is humid and In terms of tectonic divisions, the study area is located in the Zagros folded zone. It's a plain block and graben formed in an environment with potential natural hazards in developing. Because of the importance of this issue, this paper attempts to examine the efficacy of the new models with different fits most risks in this area has focused on urban planning and environmental consequences of them to sustainable urban development.Materials and methodsThis study is based on the documentary sources, field work, and fuzzy methods, geographic information system (GIS) and Idrisi Kilimanjaro are completed. The landslide hazard zoning in the study area consists of 8 layers Such as (Elevation, slope, Formations, distance from fault, distance from the stream, land use, rainfall, distance from drainage, slope) was used. For flood hazard zoning we are utilized of 7 layers such as, precipitation, distance from drainage, the basin slope, lithology Formations, land use, slope. Also for seismic hazard zonation 5 layers such as, long of the faults, distance from the fault, geological formations, underground water depth we were used. After preparing all the required layers and each layer separately were categorized. Then to classify and standardize the layers on the basis of membership in the fuzzy function. In the next phase of operational testing with multicriteria decisionmaking models TOPSIS and WLC models (MCDM) for hazard zoning and compare the outputs of these procedures were performed.Results and discussionDue to the importance risk of the floods, landslides and earthquakes in the physical development of Izeh, the different layers of information as factors for the city of Izeh in the relevant software was developed. The result of this research on the occurrence of landslides among the effective factors in study area are showed, the factor of height and lithology formation have greatest effect. The output from the TOPSISS model indicated about 7.6 % of the study area are located on the high risk zone. Also WLC models also are shoved about the 22 % of the area at risk for high to very high landslide risk. Flood hazard zonation mapping analysis shows that the method is ideal catchment area most at risk of flooding (33 percent) above shows. While in high risk flood zone WLC model is about 21%. The results of seismic hazard zonation map method TOPSISS 29 percent High and very high risk, and more than half of the area (59.8%) in the low to very low risk of earthquakes has been classifieds. While the WLC model, about 38% of the area at risk of earthquakes is high to very high.ConclusionIn this study, we analyze three important geomorphological hazards and. Among the influencing factors on landslides occurrence in the region's geological factors as the most important factor in building height and mistakes were. The most important factor showery rainfall and severe flooding in the catchment area. Seismicity in the region is the most important factor in longflute seismicity and active faults. The probability of occurrence of earthquakes with large scale it is more predictable. The overview of the outputs obtained from the two models can Izeh the expansion of the city towards the east and southeast regions are faced with a dilemma. It is because these areas are primarily at risk from flooding and landslides. The development of the western areas faced with the threat of earthquakes, so the optimum location for future expansion of the city's central basin. The results of the models showed that the risk of landslides, floods and earthquakes with TOPSIS model, respectively 35%, 33%, 29%, and the model of WLC, 22 percent, 21 percent, 38 percent of the area in the fall. These areas were identified as areas of high risk and very high. Comparison of the results showed that susceptibility to landslide and flood WLC model to model TOPSIS, tend to show that it is closer to reality. In addition TOPSIS models, the best model in relation to the hazard of earthquakes were detected