ارزیابی مقایسه‌ای استفاده از مدل‌های آماری نسبت فراوانی و آنتروپی شانون به منظور پهنه‌بندی نواحی حساس به زمین لغزش(مطالعه موردی: حوزه آبخیز تجن میانی)

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانش‌آموخته دکتری علوم و مهندسی آبخیزداری- آب، دانشکده منابع طبیعی و علوم زمین، دانشگاه کاشان

2 استادیار علوم و مهندسی آبخیزداری، دانشکده منابع طبیعی و علوم زمین، دانشگاه کاشان

3 دانشجوی دکتری علوم و مهندسی آبخیز- حفاظت آب و خاک، دانشکده منابع طبیعی و علوم زمین، دانشگاه کاشان

10.22034/gmpj.2022.350081.1364

چکیده

زمین‌لغزش به عنوان یک پدیده ژئومورفولوژیک طبیعی، در زمره بلایای طبیعی محسوب می‌شود که می‌تواند خسارات جانی و مالی فراوانی را به زندگی انسان‌ها تحمیل می‌کند؛بنابراین شناسایی مناطق حساس به وقوع زمین‌لغزش جهت کاهش خسارات امری ضروری است. هدف پژوهش‌حاضرارزیابی و ناحیه‌بندی حساسیت‌پذیری زمین‌لغزش‌درزیرحوزه آبخیزتجن‌میانی بابه‌کارگیری مدل‌های‌آماری نسبت فراوانی‌وآنتروپی شانون است.بدین منظور ابتدا 68 نقطه زمین‌لغزش برای‌منطقه شناسایی-واین نقاط به‌صورت تصادفی به دو گروه آموزش مدل(70 درصد)واعتبار مدل(30 درصد)تقسیم شدند.همچنین بر اساس مرور منابع،10 عامل شیب،جهت شیب،فاصله تاآبراهه،ارتفاع،کاربری-اراضی،سنگ‌شناسی،انحنای سطح، انحنای‌طولی،باران‌وشاخص‌رطوبت‌توپوگرافی (TWI) به‌عنوان-عوامل‌مؤثردروقوع زمین‌لغزش درمنطقه موردمطالعه انتخاب شدند.درادامه‌نقشه‌حساسیت‌پذیری-زمین‌لغزش‌بااستفاده ازمدل‌های نسبت‌فراوانی وآنتروپی‌شانون وبراساس‌روش‌شکست‌طبیعی‌برای-منطقه موردمطالعه تهیه شد.درنهایت به‌منظور ارزیابی نرخ موفقیت و پیش‌بینی مدل ازمنحنی-مشخصه‌عملکرد (ROC) استفاده شد.نتایج حاصل از تأثیر عوامل مؤثر در وقوع زمین‌لغزش در مدل آنتروپی شانون نشان داد که به ترتیب معیار‌های رطوبت توپوگرافی، کاربری اراضی و انحنای طولی با مقادیر وزن Wj به ترتیب برابر با 73/0، 66/0 و 65/0بیش‌ترین تأثیر را در وقوع زمین‌لغزش در منطقه دارند. نتایج ارزیابی نرخ موفقیت و پیش‌بینی مدل با توجه به منحنی ROC و سطح زیر منحنی (AUC) برای آموزش‌واعتبار دو مدل نسبت فراوانی و آنتروپی‌شانون به ترتیب برابر با 76/0، 72/0 و 62/0، 59/0 به دست آمدکه‌بیانگر عملکرد نسبتا خوب مدل نسبت فراوانی و عملکرد ضعیف تا مردود مدل آنتروپی شانون برای ارزیابی‌وتهیه نقشه حساسیت‌پذیری زمین‌لغزش‌درحوضه مورد مطالعه است.همچنین‌نتایج حاصل ازناحیه‌بندی حساسیت‌پذیری زمین‌لغزش در حوضه تجن-میانی بااستفاده‌ازمدل نسبت فراوانی نشان دادکه به ترتیب 156/30، 066/17 و 206/5 درصد از مساحت‌حوضه درمحدوده حساسیت متوسط،زیاد و خیلی زیاد قرار دارد.نتایج پژوهش حاضر می‌تواند جهت مدیریت‌وآمایش سرزمین‌توسط مدیران و برنامه‌ریزان به‌کارگرفته شود.

کلیدواژه‌ها


عنوان مقاله [English]

Comparative evaluation of the use of statistical models of frequency ratio and Shannon entropy in order to zone landslide-sensitive areas (case study: Middle Tajen watershed)

نویسندگان [English]

  • daniyal sayyad 1
  • Ebrahim Omidvar 2
  • Zahra Naserianasl 3
1 university of kashan
2 Department of Range and Watershed Management, Natural Resources and Geoscience, University of Kashan, Kashan, Iran
3 PhD Student of Watershed Management Sciences and Engineering, Water and Soil Conservation, Faculty of Natural Resources and Earth Sciences, University of Kashan
چکیده [English]

Introduction

The complete or partial movement of rock or soil caused by gravity is called a landslide. Landslides are considered among natural disasters and account for at least 17% of casualties caused by natural disasters, which sometimes cause the loss of life, property and infrastructure. Therefore, the first step to understand and recognize landslides and then reduce the damages caused by them is to analyze landslides using statistical methods. The frequency ratio method is a statistical analysis model and one of the most popular approaches for the analysis of landslides, which is still widely used by many researchers. Another two-variable statistical model in landslide susceptibility studies is the Shannon entropy model. Entropy is a management approach that estimates dispersion and disorder in natural phenomena and is widely used in environmental sciences. Middle Tajen watershed is one of the sub-basins of Tajen basin in Mazandaran province and due to special environmental conditions, it is prone to mass movements and landslides have occurred in different parts of it during previous periods. Therefore, it seems necessary to prepare a landslide susceptibility map with acceptable accuracy for this area. Based on this, the aim of the current research is to evaluate the comparison of two statistical models of frequency ratio and Shannon entropy to prepare a landslide susceptibility map in the middle Tajen watershed.

Methodology

In order to prepare a landslide susceptibility map with Shannon's frequency ratio and entropy statistical models, first 68 landslide points were identified for the region. Also, according to the field observations of the conditions of landslides recorded in the region, as well as a review of the sources of ten factors affecting the occurrence of landslides, including slope, aspect, distance to stream, elevation, land use, lithology, Plan Curvature, Profile Curvature, rain and Topographic Wetness Index were identified and modeling was done using these factors. The frequency ratio statistical model is a simple and understandable probabilistic model that shows the correlation between landslides in the region and the factors that cause them in the region. In the statistical model, the frequency ratio of the values of one, less than one and more than one respectively indicates the average, low and high correlation between landslides and their causing factors in the region. Entropy measures abnormal behavior, variability, instability, degree of disorder and uncertainty of a system compared to its possible initial state. In general, the concept of entropy describes the abnormality between causes and consequences or the degree of abnormality; Therefore, the Shannon entropy model is used to show the thermodynamic conditions of a system. In the prepared landslide maps, the most important question that is raised is the discussion of the accuracy and correctness of the prepared model, so the process of validating the built models is important. Therefore, In the present study, Receiver Operating Characteristics (ROC) Area Under the Curve (AUC) were used to train and validate the built model.



Results and Discussion

The results of the effect of factors affecting the occurrence of landslides in Shannon's entropy model showed that the parameters of topographic humidity, land use and longitudinal curvature with the weight values of Wj equal to 0.73, 0.66 and 0.65 respectively are the most have an effect on the occurrence of landslides in the region. The results of evaluating the success rate and predicting the model according to the ROC curve and the area under the curve (AUC) for the training and validity of the two models, frequency ratio and Shannon's entropy are respectively equal to 0.76, 0.72 and 0.62, 0.59 to It was found that it indicates the relatively good performance of the abundance ratio model and the weak to poor performance of the Shannon entropy model for evaluating and preparing a landslide susceptibility map in the studied basin. Also, the results of landslide susceptibility zoning in the middle Tajen basin using frequency ratio model showed that 30.156, 17.066 and 5.206 percent of the basin area are in the range of medium, high and very high sensitivity, respectively.



Conclusion

Landslides are one of the natural hazards that cause many human and financial losses. The zoning of landslide-prone areas, while identifying sensitive and high-risk areas, can provide the basis for the implementation of proper management plans in the slopes in order to reduce damages. In the present study, frequency ratio and Shannon's entropy models were used to evaluate the susceptibility of landslides in the middle Tajen watershed located in Mazandaran province. The results of the landslide susceptibility zoning map in the basin showed that more than half of the basin's area (52.428%) is in the moderate to very high landslide susceptibility range. According to the results obtained from the ROC curve, the frequency ratio model according to the values of the area under the curve (AUC) with success rate (0.76) and prediction rate (0.72) respectively compared to the Shannon entropy model with success rate and prediction 0.62 and 0.59, respectively, have a relatively good performance for the zoning of the landslide susceptibility map in the study area of the middle Tajen basin. Since in the last few decades, due to the change of use and destruction of natural resources, landslides have become a serious and big danger in many parts of the world, Therefore, the preparation of the landslide susceptibility zoning map plays an important role in the management of high-risk slopes and land preparation.

کلیدواژه‌ها [English]

  • mass movements of the earth
  • Middle Tajen basin
  • sensitivity
  • Bivariate models
  • Receiver Operating Characteristics