بررسي مقايسه‌اي نقش كاربري اراضي بر توليد رسوب و رواناب سطحي با استفاده از مدل SWAT (مطالعۀ موردي: حوزۀ آبخيز بهشت آباد)

Comparative Study on the Role of Land Use in Surface Runoff and Sediment Yield Using SWAT Model (A Case Syudy: Beheshtabad Watershed)

آﮔﺎﻫﯽ از ﻣﯿﺰان رواﻧﺎب و رﺳﻮب ﺗﻮﻟﯿﺪ ﺷﺪه از اراﺿﯽ ﮔﻮﻧﺎﮔﻮن ﮔﺎم ﻣﻬﻤﯽ در ﻣﺪﯾﺮﯾﺖ ﮐﺎرﺑﺮي اراﺿﯽ اﺳﺖ. از آﻧﺠﺎﯾﯽ ﮐﻪ اﻧﺪازهﮔﯿﺮي اﯾﻦ ﻣﻘﺎدﯾﺮ ﻫﻤﯿﺸــﻪ اﻣﮑﺎنﭘﺬﯾﺮ ﻧﯿﺴــﺖ، ﺷــﺒﯿﻪ ﺳــﺎزي رواﻧﺎب و رﺳــﻮب، راﻫﯽ ﺟﻬﺖ ﻧﯿﻞ ﺑﻪ ﻣﺪﯾﺮﯾﺖ ﺟﺎﻣﻊ ﺣﻮزة آﺑﺨﯿﺰ ﺧﻮاﻫﺪ ﺑﻮد. در اﯾﻦ ﻣﻄﺎﻟﻌﻪ، ﺑﺮاي ﺷﺒﯿﻪﺳﺎزي رواﻧﺎب و رﺳﻮب ﮐﺎرﺑﺮيﻫﺎي ﻣﺨﺘﻠﻒ زﻣﯿﻦ ﺷﺎﻣﻞ ﻣﺮﺗﻊ، زارﻋﺖ، ﺑﺎغ و اراﺿﯽ ﺷﻬﺮي در ﺣﻮزة آﺑﺨﯿﺰ ﺑﻬﺸﺖ آﺑﺎد ﮐﻪ ﺑﺨﺶ ﻣﻬﻤﯽ از ﺣﻮزة آﺑﺨﯿﺰ ﮐﺎرون ﺷﻤﺎﻟﯽ ﻣﯽﺑﺎﺷﺪ، ﻣﺪل SWAT ﻣﻮرد اﺳﺘﻔﺎده ﻗﺮار ﮔﺮﻓﺖ. ﺑﺪﯾﻦ ﻣﻨﻈﻮر، از دادهﻫﺎي دﺑﯽ و رﺳﻮب روزاﻧﻪ اﯾ ﺴﺘﮕﺎهﻫﺎي آب ﺳﻨﺠﯽ واﻗﻊ در ﺣﻮزة ﻣﻄﺎﻟﻌﺎﺗﯽ ا ﺳﺘﻔﺎده ﺷﺪ و ﭘﺲ از ﺗﺤﻠﯿﻞ ﺣ ﺴﺎ ﺳﯿﺖ و وا ﺳﻨﺠﯽ ﻣﺪل، ﺗﺤﻠﯿﻞ ﻋﺪم ﻗﻄﻌﯿﺖ ﻣﺪل ﺑﺎ ا ﺳﺘﻔﺎده از اﻟﮕﻮرﯾﺘﻢ 2-SUFI ﺻﻮرت ﮔﺮﻓﺖ. ﺑﺮ ا ﺳﺎس ﻧﺘﺎﯾﺞ ﺣﺎ ﺻﻠﻪ از ارزﯾﺎﺑﯽ ﮐﺎراﯾﯽ ﻣﺪل SWAT، ﻣﻘﺎدﯾﺮ ﻣﻌﯿﺎرﻫﺎي آﻣﺎري NS و R² ﺑﺮاي رواﻧﺎب در ﻣﺮﺣﻠﮥ واﺳــﻨﺠﯽ ﺑﻪ ﺗﺮﺗﯿﺐ 0/69 و0/71 و در ﻣﺮﺣﻠﮥ اﻋﺘﺒﺎرﺳــﻨﺠﯽ 0/64 و 0/66 و ﺑﺮاي رﺳــﻮب در ﻣﺮﺣﻠﻪ وا ﺳﻨﺠﯽ ﺑﻪ ﺗﺮﺗﯿﺐ 0/72 و 0/73 و در ﻣﺮﺣﻠﮥ اﻋﺘﺒﺎر ﺳﻨﺠﯽ 0/66و 0/71 ﺑﻪ د ﺳﺖ آﻣﺪ ﮐﻪ ﺗﻮاﻧﺎﯾﯽ ﻣﺪل در ﺑﺮآورد ﺻﺤﯿﺢ دﺑﯽ ﺟﺮﯾﺎن، رواﻧﺎب و رﺳﻮب در ﺣﻮزة آﺑﺨﯿﺰ ﺑﻬﺸﺖ آﺑﺎد را ﺗﺄﯾﯿﺪ ﻣﯽﻧﻤﺎﯾﺪ. ﻫﻤﭽﻨﯿﻦ ﻧﺘﺎﯾﺞ ﻧﺸﺎن داد ﮐﻪ اراﺿﯽ ﮐﺸﺖ دﯾﻢ ﺑﺎ رواﻧﺎب ﺳﻄﺤﯽ ﻣﺘﻮﺳﻂ 190 ميليمتر و رسوب متوسط 24/5 تن بر هكتار در سال و باغات با ميانگين 80 ميليمتر رواناب سطحي و متوسط توليد رسوب 1/63 تن بر هكتار در سال به ترتيب بيشترين و كمترين مقادير متوسط ساليانۀ توليد رواناب و رسوب را دارند.

Knowing the amount of runoff and sediment generated from different lands is an important step in land use management. Since it is not always possible to measure these values, modeling parameters, will be a way to achieve watershed comprehensive management. Beheshtabad watershed in Chaharmahal & Bakhtiari province with different land uses such as range land, agriculture, gardens and urban area is an important part of Northern Karun Basin. In order to simulate the amount of runoff and sediment generated in different land uses, SWAT model was used. Discharge and sediment data of weather and hydrometric stations located in the area was used for sensitivity analyses and then to calibrate and validate model by SUFI-2 algorithm. NS and R² coefficients obtained for runoff calibration are respectively 0.69, 0.71 and for runoff validation are 0.65, 0.67 and for sediment are 0.72, 0.73 in calibration, and 0.66, 0.71 in validation, that confirmed model ability to accurately estimate of flow, runoff and sediment in the study area. The results showed that dry farming lands with average runoff and sediment of 190 mm, 24.5 tons per hectare per year respectively, has the highest and gardens with an average of 80 mm runoff has the lowest sediment yield of 1.63 tons per hectare in the year.