كليدواژه :
رﺳﻮب ﻣﻌﻠﻖ , ﺑﺎر ﺑﺴﺘﺮ رودﺧﺎﻧﻪ , رﺳﻮﺑﺪﻫﯽ , ﺳﯿﻤﺎي ﺣﻮزه ﻫﺎي آﺑﺨﯿﺰ , ﻧﻘﺸﻪ ﻓﺮﺳﺎﯾﺶ ﺧﺎك ﮐﺸﻮر
چكيده فارسي :
ﺧﺎك ﺑﻪ ﻋﻨﻮان ﯾﮑﯽ از اﺟﺰاي ﻫﺮ ﺑﻮم ﺳﺎزه و ﻣﻨﺒﻊ ﻣﻬﻢ ﺗﻮﻟﯿﺪ ﻏﺬا، ﻧﻘﺶ ﺑﺴﯿﺎر ﺟﺪي در اداﻣﻪ ﺣﯿﺎت ﺑﺸﺮ دارد. ﻟﺬا، ﺿﺮورت ﺣﻤﺎﯾﺖ و ﺣﻔﺎﻇﺖ از ﺧﺎك و ﺟﻠﻮﮔﯿﺮي از ﻓﺮﺳﺎﯾﺶ آن، اﻣﺮي اﻟﺰاﻣﯽ اﺳﺖ. در ﻣﻮرد ﻣﻘﺪار ﻓﺮﺳﺎﯾﺶ و رﺳﻮب ﮐﺸﻮر، ارﻗﺎم ﻣﺘﻔﺎوت و در ﺑﺮﺧﯽ از ﭘﮋوﻫﺶ ﻫﺎ ﺗﺎ ﭼﻨﺪ ﺑﺮاﺑﺮ اﺧﺘﻼف را ذﮐﺮ ﮐﺮده اﻧﺪ. اﯾﻦ ارﻗﺎم از ﮐﻤﺘﺮ از ﯾﮏ ﺗﺎ ﺑﯿﺶ از ﭘﻨﺞ ﻣﯿﻠﯿﺎرد ﺗﻦ در ﺳﺎل ﺑﺎ ﻫﻢ ﺗﻔﺎوت دارﻧﺪ. ﻣﺤﺎﺳﺒﻪ و ﺗﺮﺳﯿﻢ ﻧﻘﺸﻪ ﻓﺮﺳﺎﯾﺶ و رﺳﻮب دﻫﯽ، اﻃﻼﻋﺎت ﻣﻬﻤﯽ را اراﺋﻪ ﻣﯽ دﻫﺪ ﮐﻪ در ﻃﺮاﺣﯽ ﺳﺪﻫﺎ، ﻣﺨﺎزن، ﮐﺎﻧﺎل ﻫﺎ، ﻋﻤﻠﯿﺎت ﺣﻔﺎﻇﺖ ﺧﺎك، ارزﯾﺎﺑﯽ ﺧﺴﺎرات ﻣﺤﻠﯽ و ﻏﯿﺮﻣﺤﻠﯽ ﻓﺮﺳﺎﯾﺶ و ﭘﺮوژه ﻫﺎي آﻣﺎﯾﺶ ﺳﺮزﻣﯿﻦ و ارزﯾﺎﺑﯽ ﻗﺎﺑﻠﯿﺖ اراﺿﯽ ﻣﻮرد اﺳﺘﻔﺎده ﻗﺮار ﻣﯽ ﮔﯿﺮد. ﻧﻘﺸﻪ ﻣﯿﺰان ﻓﺮﺳﺎﯾﺶ ﯾﮑﯽ از ﻧﻘﺸﻪ ﻫﺎي ﭘﺎﯾﻪ، ﻋﻠﻤﯽ و ﮐﺎرﺑﺮدي در ﺑﺨﺶ ﻫﺎي ﻣﺨﺘﻠﻒ اﺟﺮاﯾﯽ، ﺗﺤﻘﯿﻘﺎﺗﯽ و آﻣﻮزﺷﯽ ﻣﯽ ﺑﺎﺷﺪ. ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﺿﺮورت ﺗﻌﯿﯿﻦ ﻣﻘﺪار ﻓﺮﺳﺎﯾﺶ و رﺳﻮب ﺑﺮاي ﮐﻞ ﮐﺸﻮر و ﺗﻌﯿﯿﻦ اوﻟﻮﯾﺖ ﻫﺎي اﺟﺮاﯾﯽ در ﻣﻨﺎﻃﻖ ﺑﺎ ﭘﺘﺎﻧﺴﯿﻞ زﯾﺎد ﻓﺮﺳﺎﯾﺶ، اﯾﻦ ﭘﺮوژه ﺗﻮﺳﻂ ﭘﮋوﻫﺸﮑﺪه ﺣﻔﺎﻇﺖ ﺧﺎك و آﺑﺨﯿﺰداري ﺗﻌﺮﯾﻒ و ﺑﻪ اﻧﺠﺎم رﺳﯿﺪ. ﺑﺮ اﯾﻦ اﺳﺎس، ﺗﻔﮑﯿﮏ ﺣﻮزه ﻫﺎي آﺑﺨﯿﺰ رده ﻫﻔﺖ ﺑﻪ ﻫﻔﺖ ﻣﻨﻄﻘﻪ ﯾﺎ ﻧﺎﺣﯿﻪ ﺷﺎﻣﻞ 1( اﻟﺒﺮز ﺷﺮﻗﯽ 2( اﻟﺒﺮز ﻣﯿﺎﻧﯽ 3( اﻟﺒﺮز ﻏﺮﺑﯽ 4( اﯾﺮان ﻣﺮﮐﺰي 5( زاﮔﺮس ﺷﻤﺎﻟﯽ 6( زاﮔﺮس ﻣﯿﺎﻧﯽ و 7( زاﮔﺮس ﺟﻨﻮﺑﯽ ﺻﻮرت ﮔﺮﻓﺖ. آﻣﺎر ﺑﻠﻨﺪﻣﺪت رﺳﻮب ﺳﻨﺠﯽ 118 اﯾﺴﺘﮕﺎه در اﯾﻦ ﻣﻨﺎﻃﻖ ﻣﻮرد ﺗﺠﺰﯾﻪ و ﺗﺤﻠﯿﻞ ﻗﺮار ﮔﺮﻓﺖ و ﺑﺎ روش ﺣﺪ وﺳﻂ دﺳﺘﻪ ﻫﺎ ﻣﻘﺪار رﺳﻮب ﻫﺮ اﯾﺴﺘﮕﺎه ﺗﻌﯿﯿﻦ ﺷﺪ. ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﻣﯿﺰان ﺑﺎر ﺑﺴﺘﺮ رودﺧﺎﻧﻪ ﻫﺎ، ﺑﺎ اﺳﺘﻔﺎده از ﻣﺪل EPM ﻣﯿﺰان رﺳﻮب دﻫﯽ و ﺑﺎ در ﻧﻈﺮ ﮔﺮﻓﺘﻦ ﺿﺮﯾﺐ اﻧﺘﻘﺎل رﺳﻮب ﺣﻮﺿﻪ ﻫﺎ ﻣﯿﺰان ﻓﺮﺳﺎﯾﺶ ﺧﺎك ﺗﻌﯿﯿﻦ و ﻧﻘﺸﻪ ﻓﺮﺳﺎﯾﺶ ﺧﺎك ﮐﺸﻮر ﺑﺮاي ﺣﻮزه ﻫﺎي آﺑﺨﯿﺰ ﻣﺸﺮف ﺑﻪ اﯾﺴﺘﮕﺎه ﻫﺎي ﻫﯿﺪروﻣﺘﺮي اراﺋﻪ ﺷﺪ. ﻧﺘﺎﯾﺞ ﻧﺸﺎن داد ﮐﻪ ﻣﯿﺎﻧﮕﯿﻦ رﺳﻮب دﻫﯽ و ﻣﯿﺰان ﻣﺘﻮﺳﻂ وزﻧﯽ ﻓﺮﺳﺎﯾﺶ ﺧﺎك در ﺣﻮﺿﻪ ﻫﺎي ﻣﺸﺮف ﺑﺮ اﯾﺴﺘﮕﺎه ﻫﺎي داراي آﻣﺎر رﺳﻮب در ﮐﺸﻮر، ﺑﻪ ﺗﺮﺗﯿﺐ 3/3 و 16 ﺗﻦ در ﻫﮑﺘﺎر در ﺳﺎل اﺳﺖ. ﮐﻤﺘﺮﯾﻦ و ﺑﯿﺸﺘﺮﯾﻦ ﻣﯿﺰان ﻓﺮﺳﺎﯾﺶ ﺧﺎك ﺑﻪ ﺗﺮﺗﯿﺐ ﺑﺎ ﻣﻘﺎدﯾﺮ 9 و 32/4 ﺗﻦ در ﻫﮑﺘﺎر در ﺳﺎل ﻣﺘﻌﻠﻖ ﺑﻪ ﻣﻨﺎﻃﻖ زاﮔﺮس ﻣﯿﺎﻧﯽ و زاﮔﺮس ﺟﻨﻮﺑﯽ اﺳﺖ.
چكيده لاتين :
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.
