طبقه‌بندی خودکار لندفرم‌ها (acl) با دو مدل ویژگی‌های زمین (ta) و شاخص موقعیت توپوگرافی (tpi) در دامنه‌های شمال شرقی ارتفاعات کرکس‌کوه نطنز و کاشان

عوارض سطح زمین یک مبنا در مطالعات ژئومورفیک در نظر گرفته میشوند که شناسایی و نقشه برداری آنها به عنوان یک مرز مشخص برای فرآیندهای عملیاتی، امکان شناخت عمیق تر از محیط طبیعی، انجام مطالعات پایدار، ارزیابی، پیش بینی و برنامه ریزی را در سطح یک چشم انداز فراهم میکند. با توجه به مزایای روشهای شناسایی خودکار عوارض نسبت به متدهای سنتی بصری، هدف تحقیق حاضر طبقهبندی اتوماتیک لندفرمهای دامنههای شمال شرقی ارتفاعات کرکسکوه نطنز و کاشان با مساحتی به گستردگی 4739 کیلومترمربع می‌باشد. در این راستا، از دو مدل ویژگی‌های زمین (ta) و شاخص موقعیت توپوگرافی (tpi) که هر دو مبتنی بر مدل رقومی ارتفاعی (dem) هستند، بهره گرفته شد. در مدل ta که از ارتفاع، شیب، انحنا و شدت برجستگی به عنوان ورودی استفاده می‌شود، لندفرم‌ها به پنج کلاس قله، شانه دامنه، پشت دامنه، پای دامنه و پنجه دامنه طبقه‌بندی شدند و در مدل tpi به شش کلاس ستیغ، شیب‌های بالایی، شیب‌های میانی، شیب‌های مسطح، شیب‌های پایینی و دره‌ها دسته‌بندی شدند. نتایج حاصل از طبقه‌بندی مورفولوژیکی منطقه مطالعاتی با متد ویژگی‌های زمین نشان می‌دهد که فرم پادگانه‌های بالایی یا شانه دامنه با مساحت 1810 کیلومترمربع که حدود 38 درصد مساحت منطقه را در برمی‌گیرد، فرم غالب چشم‌انداز محدوده مطالعاتی می‌باشد. طبقه‌بندی لندفرم‌ها با شاخص موقعیت توپوگرافی (tpi) نیز نشان می‌دهد که لندفرم دره با مساحت 1872 کیلومترمربع معادل حدود 40 درصد مساحت منطقه مورد مطالعه، به‌عنوان لندفرم غالب محسوب می‌شود. استفاده از چهار ورودی در مدل ویژگی‌های زمین و امکان طبقه‌بندی گسترده‌تر در شاخص موقعیت توپوگرافی از جمله مزایایی این مدل‌ها هستند. از نتایج حاصل از طبقه‌بندی لندفرم‌ها در این دو مدل می‌توان برای مطالعات بعدی به‌خصوص در زمینه ژئومورفولوژی خاک استفاده کرد.

automatic classification of landforms (acl) with two models of terrain attributes (ta) and topographic position index (tpa) in the northeast slopes of natanz and kashan karkas heights

automatic classification of landforms (acl) with two models of terrain attributes (ta) and topographic position index (tpa) in the northeast slopes of natanz and kashan karkas heightsintroductiongeomorphology studies the forms and processes of earth’s surface reliefs and their changes over time. obtaining information about landforms and mapping of them re considered not only as a basis for different types of geomorphological research, but also for landscape evaluation, suitability studies, erosion studies, hazard prediction and various fields of landscape and regional planning or land system inventories is essential. recognition and extracting of landforms using traditional methods is time-consuming, costly, and affected by opaque and often unrepeatable decisions of the interpreter. consequently, to accurately describe the topographical structure, new spatial analysis procedures and models need to be developed. accessibility of digital elevation models, software development and increasing computational power of computers provide geomorphologists with tools and opportunities which may revolutionize their discipline. nowadays, the automatic recognition of landforms is regarded as one of the most important procedures to classify landforms and deepen the understanding on the morphology of the earth. the main purpose of the study is automatic classification of landforms and separation of the landscape of the northeast slopes of natanz and kashan karkas heights into landform classes using two methods of classification of terrain attributes (ta) and topographic position index (tpa).methodology- case studythe northeast slopes of natanz and kashan karkas heights was selected as the case area in the current study. the geocoordinates of the area are between e 33° 25′ 51′′ to e 34° 11′ 16′′ and n 50° 54′ 19′′ to n 52° 9′ 49′′ based on the world geodetic system 1984 (wgs84), with a total area of 4,739 km2.- landform classification process using terrain attributesthe purpose of many models for the recognition and classification of landforms is to determine the froms of the hillslope. terrain attributes is also one of these models. chabala et al. (2013) used this model for the first time to landform classification for digital soil mapping in the chongwe-rufunsa area, zambia. the selected attributes were elevation, slope, relief intensity, and curvature. terrain attributes derived from a digital elevation model were overlaid using cell statistics to generate a landform map with five classes: (1) hills (summit), (2) upper terraces (shoulder), (3) plateau (back slope), (4) foot slope and (5) lowlands (toe slope).- landform classification process using topographic position indextpi is only one of a vast array of morphometric properties based on neighboring areas that can be useful in topographic and dem analysis. the classification using tpi is the difference between elevation value on pixel and the average elevation of the neighboring pixels. positive values mean that the analyzed pixel has values greater than the surrounding values, while negative indicates that it is smaller. tpi values near zero are either flat areas (where the slope is near zero) or areas of constant slope (where the slope of the point is significantly greater than zero). using topographic position index (tpi), a landform classification map of the study area was generated. the classification has six classes: (1) valleys, (2) lower slopes, (3) gentle slopes, (4) steep slopes, (5) upper slopes and (6) ridges.results and discussion- landform generation using terrain attributesthe landform map was generated by overlaying the reclassified grids representing relief intensity, curvature, elevation and slope. this was done using the cell statistics tool in arcmap with the mean set as the overlay statistic. the results of the landform classification are shown the landform of the upper terraces (shoulder) with an area of 1,810 km2., which covers about 38% of the studied area, is the dominant landform of the landscape of the study area.- landform generation using topographic position indexland facet corridor extension introduced for arcmap software was used to classify landform elements with tpi model. the valleys landform with an area of 1872 square kilometers, equivalent to about 40% of the study area, is considered as the dominant landform of the study area.conclusionthis research aims to landform classification and mapping of the northeast slopes of natanz and kashan karkas heights using terrain attributes (ta) and topographic position index (tpi) which both methods depend on digital elevation models (dems). considering that the terrain attributes model uses the four parameters of height above mean sea level, topographic slop, curvature and relief intensity as input for processing and classifying landforms, it can potentially have higher accuracy than the tpi model that only uses dem to identify features.keywordslandform recognition, automatic classification of landform, terrain attributes model, topographic position index, karkas heights.