نوع مقاله : مقاله پژوهشی
نویسندگان
1 استاد، پژوهشکده حفاظت خاک و آبخیزداری، سازمان تحقیقات، آموزش و ترویج کشاورزی، تهران، ایران
2 دانشیار پژوهشکده حفاظت خاک و آبخیزداری، سازمان تحقیقات، آموزش و ترویج کشاورزی، تهران، ایران
چکیده
خاک به عنوان یکی از اجزای هر بومسازه و منبع مهم تولید غذا، نقش بسیار جدی در ادامه حیات بشر دارد. لذا، ضرورت حمایت و حفاظت از خاک و جلوگیری از فرسایش آن، امری الزامی است. در مورد مقدار فرسایش و رسوب کشور، ارقام متفاوت و در برخی از پژوهشها تا چند برابر اختلاف را ذکر کردهاند. این ارقام از کمتر از یک تا بیش از پنج میلیارد تن در سال با هم تفاوت دارند. محاسبه و ترسیم نقشه فرسایش و رسوبدهی، اطلاعات مهمی را ارائه میدهد که در طراحی سدها، مخازن، کانالها، عملیات حفاظت خاک، ارزیابی خسارات محلی و غیرمحلی فرسایش و پروژههای آمایش سرزمین و ارزیابی قابلیت اراضی مورد استفاده قرار میگیرد. نقشه میزان فرسایش یکی از نقشههای پایه، علمی و کاربردی در بخشهای مختلف اجرایی، تحقیقاتی و آموزشی میباشد. با توجه به ضرورت تعیین مقدار فرسایش و رسوب برای کل کشور و تعیین اولویتهای اجرایی در مناطق با پتانسیل زیاد فرسایش، این پروژه توسط پژوهشکده حفاظت خاک و آبخیزداری تعریف و به انجام رسید. بر این اساس، تفکیک حوزههای آبخیز رده هفت به هفت منطقه یا ناحیه شامل 1) البرز شرقی 2) البرز میانی 3) البرز غربی 4) ایران مرکزی 5) زاگرس شمالی 6) زاگرس میانی و 7) زاگرس جنوبی صورت گرفت. آمار بلندمدت رسوبسنجی 118 ایستگاه در این مناطق مورد تجزیه و تحلیل قرار گرفت و با روش حد وسط دستهها مقدار رسوب هر ایستگاه تعیین شد. با توجه به میزان بار بستر رودخانهها، با استفاده از مدل EPM میزان رسوبدهی و با در نظر گرفتن ضریب انتقال رسوب حوضهها میزان فرسایش خاک تعیین و نقشه فرسایش خاک کشور برای حوزههای آبخیز مشرف به ایستگاههای هیدرومتری ارائه شد. نتایج نشان داد که میانگین رسوبدهی و میزان متوسط وزنی فرسایش خاک در حوضههای مشرف بر ایستگاههای دارای آمار رسوب در کشور، بهترتیب 3.3 و 16 تن در هکتار در سال است. کمترین و بیشترین میزان فرسایش خاک بهترتیب با مقادیر 9 و 32.4 تن در هکتار در سال متعلق به مناطق زاگرس میانی و زاگرس جنوبی است.
کلیدواژهها
عنوان مقاله [English]
Soil erosion mapping in sediment gauged watersheds of Iran
نویسندگان [English]
- Davood Nikkami 1
- Samad Shadfar 2
1 Professor, Soil Conservation and Watershed Management Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Tehran, Iran
2 Associate Professor, Soil Conservation and Watershed Management Research Institute, Agricultural Research,; Education and Extension Organization (AREEO), Tehran, Iran
چکیده [English]
Soil, as one of the components of any ecosystem and an important source of food production, has a very serious role in the continuation of human life. Therefore, the need to support and protect the soil and prevent its erosion is essential. Regarding the amount of soil erosion and sediment yield in the country, different figures have been mentioned and in some studies, the difference is with several times. These figures vary from less than one to more than five billion tons per year. Therefore, calculating and plotting erosion and sedimet yield maps provides important information that is used in the design of dams, reservoirs, canals, soil protection operations, onsite and offsite erosion damage assessment, and land use planning and land capability assessment projects. Soil erosion map is one of the basic, scientific and applied maps in various executive, research and educational sectors. Due to the need of determining the amount of soil erosion and sediment yield for the entire country and determining the executive priorities in areas with high soil erosion potential, this project was defined and carried out by the Soil Conservation and Watershed Management Research Institute. Accordingly, the watersheds of the seventh category were divided into seven regions or districts, including 1) Eastern Alborz 2) Middle Alborz 3) Western Alborz 4) Central Iran 5) North Zagros 6) Middle Zagros and 7) South Zagros. Long-term sedimen data of 118 hydrometric stations in these areas were analyzed and the amount of sediment in each station was determined by the logged mean load within discharge classes method. According to the amount of river bedload rates and using EPM model, the amount of sediment yield and cosidering sediment delivery ratio of watersheds, the amount of soil erosion were etermined and the soil erosion map of watersheds overlooking hydrometric stations was prepared. Results showed that the average sediment yield and soil erosion in the watersheds overlooking hydrometric stations are 3.3 and 16 tons per hectare per year, respectively. The lowest and highest soil erosion rates of 9 and 32.4 tons per hectare, belong to the Middle Zagros and South Zagros regions, respectively.
کلیدواژهها [English]
- Hydrometric station
- National soil erosion map
- River bedload
- Sediment yield
- Watershed landscape
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