برآورد مقادیر فرسایش و رسوب با مقایسه مدل های تجربی ( محدوده مورد مطالعه: حوضه رودخانه زیمکان شهرستان دالاهو استان کرمانشاه )

امروزه فرسایش خاک به عنوان یکی از مباحث مهم مدیریت حوضه های آبریز در سطح ملی و جهانی مطرح است. چون محاسبه مقادیر فرسایش و رسوب از طریق ایستگاه های هیدرومتری و رسوب- سنجی و اندازه گیریهای مستقیم در نقاط مختلف حوضه ها، فرایندی هزینه بر و زمان بر است، لذا یافتن روش های تجربی برای برآورد دقیق میزان فرسایش و رسوب دهی حوضه های آبریز امری ضروری و اجتناب ناپذیر به نظر می رسددر این پژوهش به ارزیابی کارآیی دو مدل epm ,rusle جهت برآورد مقادیر فرسایش خاک ورسوب حوضه آبریز رودخانه زمکان پرداخته شد که در این راستا عوامل چهارگانه مدل epm شامل فرسایش حوضه ، استفاده از زمین و حساسیت خاک و سنگ به فرسایش و شیب متوسط حوضه و همچنین عوامل مدل rusle شامل عامل فرسایندگیبارندگی (r)، عامل فرسایش‌پذیری خاک (k)، عامل طول شیب (l)، عامل درجه شیب زمین (s)، عامل پوشش‌گیاهی (c) و عامل حفاظت خاک (p) مورد تحلیل قرار گرفتدر ادامه از نرم افزار arcgis و تصاویر سنجنده ماهواره sentinel 2 در محیط envi 5.3 جهت تهیه لایه های مرتبط استفاده گردید نتایج نشان داد مقادیر فرسایش در دو مدل rusle و epm به ترتیب 5 / 4018 ، 2 / 6401 (تن در سال) و مقادیر رسوب به ترتیب 7 / 2315 ، 72 / 3624 (تن در سال) بوده و کلاس و شدت فرسایش پذیری حوضه از لحاظ هدر رفت خاک در وضعیت شدید قرار دارد که بیشترینشدت فرسایش و تولید رسوب در بخش های جنوب و جنوب غرب حوضه مشاهده شد. با توجه به نزدیک بودن مقادیر رسوب برآورد شده در مدل rusle به مقادیر مشاهدات واقعی 11 / 2559 (تن در هکتار در سال) در نهایت مشخص شد که مدل rusle نسبت به مدل epm جهت برآورد میزان فرسایش و رسوب در حوضه مورد مطالعه کارآیی و دقت بیشتری داشته و قابل اعتمادتر می باشد. همچنین پیشنهاد می گردد در کنار مدل rusle از مدل epm به عنوان الگوی سایه و فرعی جهت اجرای فازهای اولیه شناسایی، توجیهی و اجمالی در پژوهش استفاده شود.

estimation of erosion rate and estimation of sedimentation by comparing experimental models (study area of zimkan river basin, dalaho city, kermanshah province)

today, soil erosion is considered as one of the important issues of watershed management at the national and global level. considering that the calculation of erosion and sediment values through hydrometric and sediment measurement stations and direct measurements in different parts of the basins is a costly and time-consuming process.therefore, finding experimental methods to accurately estimate the amount of erosion and sedimentation of watersheds seems necessary and inevitable.erosion is a process in which soil particles are separated from their substrate by erosive agents and transported to another place with the help of one of the transfer agents.if the particle separator is wind and refrigerator. it is called wind erosion and glacial erosion respectively.water erosion also occurs due to improper land management, destruction of vegetation and lack of water flow control, and causes surface runoff and soil transfer.methodologyzimkan river basin is located in the north of dalaho city and west of kermanshah province. this basin is limited from the south and east to the zamkan dam basin,from the west to the piran basin and from the north to the posht teng basin and the lima river basin. the basin is located at the geographical coordinates of 46°4΄ to 46°11 ΄ east longitude and 34°35 ΄ to 34°22΄ north latitude. among the residential areas in the basin, we can mention the villages of ghoshchi bashi, asiyab tanureh, deh kohene, seyed baqer and reza ali farm. the studied basin has an area of 2324 square kilometers and an average height of 2044.42 meters.in general, there are two methods for measuring erosion and sedimentation; direct and indirect. direct methods are carried out using various measuring tools and devices. in these methods, erosion and sedimentation are usually measured in stages and in different ways and their amounts are presented quantitatively.in this research, two epm and rusle models are compared in order to estimate erosion and deposition, and in this regard, the factors of the two methods are investigated.the four factors of the epm model include:1. basin erosion2. land use3. sensitivity of soil and rock to erosion4. the average slope of the basinand also the inputs of rusle model include:1. rainfall erosion factor (r)2. soil erodibility factor (k)3. slope length factor (l)4. slope factor (s)5. plant cover agent (c)6. soil protection agent (p)these factors are evaluated. and the soil erosion maps obtained from two models are obtained from the results of the models.results and discussionin this research, epm and rusle models and rs and gis techniques were used to determine the erosion intensity and sedimentation potential of the studied basin. and according to the results of these two models, effective factors in erosion were evaluated and scored, and according to the relationship between sedimentation rate and sedimentation rate, the sedimentation potential of the basin was determined. also, the amount of erosion and its severity were evaluated and its digital map was prepared and drawn with the help of gisconclusionaccording to the expected results of the statistical tests by spss and gis software, finally the rusle model was chosen as a more reliable model than the epm model to estimate the amount of erosion and sedimentation in the researched basin, and the epm model was chosen as the shadow and secondary model. it will be determined after the rusle model. therefore, the aim of this research is to introduce the rusle model in the estimation of erosion and sedimentation and finally to provide an optimal and compatible model for the zimkan river basin, which is located in dalaho city, kermanshah province.methodologyzimkan river basin is located in the north of dalaho city and west of kermanshah province. this basin is limited from the south and east to the zamkan dam basin,from the west to the piran basin and from the north to the posht teng basin and the lima river basin. the basin is located at the geographical coordinates of 46°4΄ to 46°11 ΄ east longitude and 34°35 ΄ to 34°22΄ north latitude. among the residential areas in the basin, we can mention the villages of ghoshchi bashi, asiyab tanureh, deh kohene, seyed baqer and reza ali farm. the studied basin has an area of 2324 square kilometers and an average height of 2044.42 meters.in general, there are two methods for measuring erosion and sedimentation; direct and indirect. direct methods are carried out using various measuring tools and devices. in these methods, erosion and sedimentation are usually measured in stages and in different ways and their amounts are presented quantitatively.in this research, two epm and rusle models are compared in order to estimate erosion and deposition, and in this regard, the factors of the two methods are investigated.the four factors of the epm model include:1. basin erosion2. land use3. sensitivity of soil and rock to erosion4. the average slope of the basinand also the inputs of rusle model include:1. rainfall erosion factor (r)2. soil erodibility factor (k)3. slope length factor (l)4. slope factor (s)5. plant cover agent (c)6. soil protection agent (p)these factors are evaluated. and the soil erosion maps obtained from two models are obtained from the results of the models.results and discussionin this research, epm and rusle models and rs and gis techniques were used to determine the erosion intensity and sedimentation potential of the studied basin. and according to the results of these two models, effective factors in erosion were evaluated and scored, and according to the relationship between sedimentation rate and sedimentation rate, the sedimentation potential of the basin was determined. also, the amount of erosion and its severity were evaluated and its digital map was prepared and drawn with the help of gis