برآورد فرسايش و رسوب حوضه بالادست سد وشمگير

Estimation of erosion and sediment in the Vashmgir dam upstream basin

ﺑﻪ دﻟﯿﻞ اﻫﻤﯿﺖ آب و ﻧﻘﺶ ﺣﯿﺎﺗﯽ آن در زﻧﺪﮔﯽ اﻧﺴـﺎن، ﻣﻄﺎﻟﻌﺎت رودﺧﺎﻧﻪاي و ﺑﻪ ﺗﺒﻊ آن ﻣﻄﺎﻟﻌﻪ ﺑﺮ روي ﺣﻮﺿـﻪﻫﺎي آﺑﺮﯾﺰ ﺿـﺮوري ﺑﻪ ﻧﻈﺮ ﻣﯽرﺳـﻨﺪ. اﺳـﺘﺎن ﮔﻠﺴـﺘﺎن ﺑﺎ ﻣﺴـﺎﺣﺖ 20437 ﮐﯿﻠﻮﻣﺘﺮﻣﺮﺑﻊ ﺑﯿﻦ ﻋﺮض ﺟﻐﺮاﻓﯿﺎﯾﯽ ΄24 ˚36 ﺗﺎ ΄0 ˚38 ﺷـﻤﺎﻟﯽ و ΄ 51˚ 53ﺗﺎ ΄ 14˚56 ﺷـﺮﻗﯽ واﻗﻊ ﺷـﺪه اﺳـﺖ. ﮔﺮﮔﺎنرود ﯾﮑﯽ از ﻣﻬﻢﺗﺮﯾﻦ رودﺧﺎﻧﻪﻫﺎي اﺳـﺘﺎن ﮔﻠﺴـﺘﺎن ﺑﻪ ﺷـﻤﺎر ﻣﯽرود و در ﺗﻤﺎﻣﯽ دﺷـﺖ ﮔ ﺮﮔﺎن ﺟﺮﯾﺎن داﺷـﺘﻪ و آن را ﺑﻪ دو ﻗﺴـﻤﺖ ﺗﻘﺴـﯿﻢ ﻣﯽﮐﻨﺪ. ﺳـﻄﺢ ﺣﻮﺿـﻪ آﺑﮕﯿﺮ آن ﺑﻪ ﻣﺴـﺎﺣﺖ 10250ﮐﯿﻠﻮﻣﺘﺮﻣﺮﺑﻊ ﻣﯽﺑﺎﺷـﺪ. ﮔﺎم اﺻﻠﯽ و ﻣﻬﻢ در ﻣﻄﺎﻟﻌﺎت ﻓﺮﺳﺎﯾﺶ و رﺳـﻮب ﺑﻪ روش ﺗﺠﺮﺑﯽ ، ﺗﻌﯿﯿﻦ و ﺷـﻨﺎﺳـﺎﯾﯽ اﺷـﮑﺎل، و ﺳـﯿﻤﺎي ﻓﺮﺳـﺎﯾﺶ اﺳـﺖ. در اﯾﻦ ﻣﺮﺣﻠﻪ ﻧﻘﺸـﻪﻫﺎي ﻣﺨﺘﻠﻒ ﺷـﺎﻣﻞ ﺷـﺒﮑﻪ آﺑﺮاﻫﻪ، ﺷـﯿﺐ، زﻣﯿﻦﺷـﻨﺎﺳـﯽ، ژﺋﻮﻣﻮرﻓﻮﻟﻮژي، ﺧﺎكﺷـﻨﺎﺳـﯽ و ﮐﺎرﺑﺮي اراﺿـﯽ ﻣﻮرد ﺑﺮرﺳـﯽ ﻗﺮار ﮔﺮﻓﺖ؛ و ﻧﻘﺸـﻪ واﺣﺪ ﮐﺎري ﻣﻨﻄﻘﻪ ﻣﺸـﺨﺺ و ﺑﺎ ﺗﻔﺴـﯿﺮ ﻋﮑﺲﻫﺎي ﻫﻮاﯾﯽ و ﺑﺎزدﯾﺪﻫﺎي ﻣﯿﺪاﻧﯽ ﻧﻘﺸـﻪ ﺗﺪﻗﯿﻖ ﮔﺮدﯾﺪ. ﺟﻬﺖ ﺑﺮآورد ﻣﯿﺰان ﻓﺮﺳـﺎﯾﺶ و رﺳـﻮب در زﯾﺮﺣﻮﺿـﻪﻫﺎ از ﻣﺪل MPSIAC اﺳـﺘﻔﺎده ﺷـﺪ. ﻃﺒﻖ ﺑﺮرﺳـﯽﻫﺎي ﻣﯿﺪاﻧﯽ ﺻـﻮرت ﮔﺮﻓﺘﻪ و ﻧﺘﺎﯾﺞ ﺑﺪﺳـﺖ آﻣﺪه اﻧﻮاع ﻓﺮﺳـﺎﯾﺶﻫﺎ، در ﺳـﻄﺢ ﻣﻮرد ﻣﻄﺎﻟﻌﻪ ﺑﻪ وﻗﻮع ﭘﯿﻮﺳـﺘﻪ اﺳـﺖ. ﻃﺒﻖ ﺑﺮرﺳـﯽﻫﺎي ﺻـﻮرت ﮔﺮﻓﺘﻪ ﺑﯿﺸـﺘﺮﯾﻦ ﻓﺮﺳـﺎﯾﺶ در زﯾﺮ ﺣﻮﺿـﻪ ﺑﺎ ﮐﺪ 1625220)ﺑﺎر ﺑﺴـﺘﺮ 3/62 و ﺑﺎ ﻣﻌﻠﻖ 14/47( و ﮐﻤﺘﺮﯾﻦ ﻓﺮﺳـﺎﯾﺶ در زﯾﺮ ﺣﻮﺿـﻪ ﺑﺎ ﮐﺪ 1624210)ﺑﺎر ﺑﺴـﺘﺮ 0/32و ﺑﺎر ﻣﻌﻠﻖ 1/3( ﺑﻮد. ﺑﺮ اﺳـﺎس ﻧﺘﺎﯾﺞ ﺑﺪﺳـﺖ آﻣﺪه ﻧﺴـﺒﺖ ﺗﺤﻮﯾﻞ رﺳـﻮب در زﯾﺮ ﺣﻮﺿـﻪﻫﺎي ﻣﻮرد ﺑﺮرﺳـﯽ ﺑﯿﻦ ﺣﺪاﮐﺜﺮ 23/6 اﻟﯽ 39/6 درﺻـﺪ ﻣﯽﺑﺎﺷـﺪ. در ﻫﻤﯿﻦ راﺳـﺘﺎ ﻣﯿﺰان رﺳـﻮب وﯾﮋه ﺑﯿﻦ 1/6اﻟﯽ 18/1و ﻓﺮﺳـﺎﯾﺶ وﯾﮋه ﺑﯿﻦ 4/9اﻟﯽ 58/3 ﺗﻦ در ﻫﮑﺘﺎر در ﺳﺎل ﻣﺘﻐﯿﺮ ﺑﻮد.

Due to the importance of water and its vital role in human life, river studies and consequently studies on watersheds seem necessary. Golestan province with an area of 20437 square kilometers is located between latitude 36˚ 24΄ to 38˚ 0΄ north and 53˚ 51΄ to 56˚ 14΄ east. Gorganrood is one of the most important rivers in Golestan province and flows in the whole plain of Gorgan and divides it into two parts. Its catchment area is 10,250 km2. The main and important step in the study of erosion and sedimentation by experimental method is to determine and identify the forms and appearance of erosion. At this stage, various maps including river network, slope, geology, geomorphology, soil science and land use were studied; The map of the region was determined and the map was verified by interpreting aerial photographs and field visits. MPSIAC model was used to estimate the amount of erosion and sediment in the sub-basins. According to field studies and the results obtained, various types of erosions have occurred in the study area. According to the studies, the highest erosion was under the basin with code 1625220 (bed load 3.62 and with suspension 14.47) and the lowest erosion was under the basin with code 1624210 (bed load 0.32 and suspended load 1.3). Based on results, the sediment delivery ratio in the studied basins is between 23.6 to 39.6%. thus, the amount of special sediment varied between 1.6 to 18.1 and special erosion between 4.9 to 58.3 tons per hectare per year.