تعيين ويژگي‌هاي مؤثر بر هدررفت خاك ناشي از آبكندها، مطالعه موردي: فتح‌آباد-بوئين‌زهرا

Determination of effective factors on soil loss caused by gullies using drone, a case study of Fatah Abad, Buin Zahra

ﻣﺪﯾﺮﯾﺖ ﻓﺮﺳﺎﯾﺶ آﺑﮑﻨﺪي ﻧﯿﺎزﻣﻨﺪ ﺷﻨﺎﺧﺖ ﻋﻮاﻣﻞ ﻣﺆﺛﺮ ﺑﺮ آن اﺳﺖ. اﯾﻦ ﭘﮋوﻫﺶ، ﺑﺎﻫﺪف ﻃﺒﻘﻪ ﺑﻨﺪي آﺑﮑﻨﺪﻫﺎ و ﺗﻌﯿﯿﻦ ﻣﺆﺛﺮﺗﺮﯾﻦ وﯾﮋﮔﯽ ﻫﺎي ﻣﺆﺛﺮ ﺑﺮ ﻫﺪررﻓﺖ ﺧﺎك در ﻣﻨﻄﻘﻪ ﻓﺘﺢ آﺑﺎد ﺑﻮﯾﯿﻦ زﻫﺮا در اﺳﺘﺎن ﻗﺰوﯾﻦ اﻧﺠﺎم ﺷﺪ. ﻣﺤﻞ ﺑﺎﻻﮐﻨﺪ 24 آﺑﮑﻨﺪ ﻣﻨﺘﺨﺐ ﺑﺎ ﺳﺎﻣﺎﻧﻪ ﻣﻮﻗﻌﯿﺖ ﯾﺎب ﺟﻬﺎﻧﯽ ﺛﺒﺖ و ﻣﺸﺨﺼﺎت ﺷﮑﻠﯽ ﻣﺜﻞ ﻃﻮل، ﻋﺮض و ﻋﻤﻖ آن ﻫﺎ اﻧﺪازه ﮔﯿﺮي ﺷﺪ. ﺣﺠﻢ ﮐﻞ ﻫﺪررﻓﺖ ﺧﺎك ﺑﺎ ﺟﻤﻊ اﺣﺠﺎم ﺟﺰﺋﯽ در ﻣﻘﺎﻃﻊ ﺗﻐﯿﯿﺮ ﺷﮑﻞ آﺑﮑﻨﺪ ﺗﻌﯿﯿﻦ ﺷﺪ. ﻧﻤﻮﻧﻪ ﻫﺎي ﺳﻄﺤﯽ ﺧﺎك از ﺑﺎﻻﮐﻨﺪ ﺗﻬﯿﻪ و ﻧﻮع ﺑﺎﻓﺖ، pH ،EC، ﻣﺎده آﻟﯽ و ﺑﺮﺧﯽ آﻧﯿﻮن ﻫﺎ و ﮐﺎﺗﯿﻮن ﺗﻌﯿﯿﻦ ﺷﺪﻧﺪ. ﺷﺎﺧﺺ ﻫﺎي ﻣﺮﺗﺒﻂ ﺑﻪ ﺷﮑﻞ آﺑﺨﯿﺰ از ﻣﺪل رﻗﻮﻣﯽ ارﺗﻔﺎع ﺣﺎﺻﻞ از ﭘﺮدازش ﺗﺼﺎوﯾﺮ ﭘﻬﭙﺎد اﺳﺘﺨﺮاج ﺷﺪ. ﮔﺮوه ﺑﻨﺪي آﺑﮑﻨﺪﻫﺎ، ﻫﻤﺒﺴﺘﮕﯽ ﺑﯿﻦ ﻋﻮاﻣﻞ و ﺗﺠﺰﯾﻪ ﺑﻪ ﻣﺆﻟﻔﻪ ﻫﺎي اﺻﻠﯽ ﺑﻪﺗﺮﺗﯿﺐ ﺑﺎ اﺳﺘﻔﺎده از ﺗﺤﻠﯿﻞ ﺧﻮﺷﻪاي و رﮔﺮﺳﯿﻮن ﭼﻨﺪ ﻣﺘﻐﯿﺮه ﺑﻪ روش ﮔﺎم ﺑﻪ ﮔﺎم اﻧﺠﺎم ﺷﺪ. ﻧﺘﺎﯾﺞ ﺗﺤﻘﯿﻖ ﻧﺸﺎن داد، آﺑﮑﻨﺪﻫﺎ داراي ﺑﺎﻻﮐﻨﺪ ﻋﻤﻮﻣﺎً ﻋﻤﻮدي، ﻣﻘﻄﻊ ﻋﺮﺿﯽ ذوزﻧﻘﻪ اي ﺷﮑﻞ و داراي ﭘﻼن ﻋﻤﻮﻣﯽ ﺧﻄﯽ ﻫﺴﺘﻨﺪ. ﻣﺘﻮﺳﻂ ﻋﻤﻖ ﺑﺎﻻﮐﻨﺪ، ﻋﻤﻖ در 50 درﺻﺪ ﻃﻮل آﺑﮑﻨﺪ و ﻣﺘﻮﺳﻂ ﻃﻮل آن ﻫﺎ ﺑﻪﺗﺮﺗﯿﺐ 0/6 ،0/4 و 25 ﻣﺘﺮ ﺑﻮد. ﺑﺎﻓﺖ ﺧﺎك ﻟﻮم و ﻣﺘﻮﺳﻂ اﺟﺰاي ﺗﺸﮑﯿﻞ دﻫﻨﺪه ﺑﺎﻓﺖ ﺧﺎك ﺷﺎﻣﻞ ﺷﻦ، ﺳﯿﻠﺖ و رس ﺑﻪ ﺗﺮﺗﯿﺐ 46 ،30 و 24 درﺻﺪ ﺑﻪ دﺳﺖ آﻣﺪ. ﻣﺘﻮﺳﻂ ﺷﻮري ﻫﺸﺖ -dSm و ﻣﺘﻮﺳﻂ pH ﻧﻤﻮﻧﻪ ﻫﺎ 8/4 ﺑﻮد. ﺣﺠﻢ ﮐﻞ ﻫﺪررﻓﺖ ﺧﺎك ﺑﺎ ﻣﺘﻐﯿﺮﻫﺎي ﺑﻪ ﺗﺮﺗﯿﺐ ﺳﻄﺢ ﻣﻘﻄﻊ ﻣﺘﻮﺳﻂ، ﻣﺘﻮﺳﻂ ﻋﺮض ﭘﺎﯾﯿﻦ و ﺑﺎﻻي آﺑﮑﻨﺪ، ﻣﯿﺰان ﺷﻦ، ﻣﺘﻮﺳﻂ ﻋﻤﻖ آﺑﮑﻨﺪ و ﻃﻮل ﮐﻞ داراي ﺿﺮاﯾﺐ ﻫﻤﺒﺴﺘﮕﯽ ﺑﯿﺸﺘﺮ از 0/6 و در ﺳﻄﺢ ﯾﮏ درﺻﺪ ﻣﻌﻨﯽ دار ﺑﻮدﻧﺪ. ﻧﺘﺎﯾﺞ رﮔﺮﺳﯿﻮن ﭼﻨﺪ ﻣﺘﻐﯿﺮه ﻧﯿﺰ ﻧﺸﺎن داد ﮐﻪ از ﻣﺆﺛﺮﺗﺮﯾﻦ وﯾﮋﮔﯽﻫﺎي ﻣﺆﺛﺮ ﺑﺮ ﻫﺪررﻓﺖ ﺧﺎك ﺑﻪوﺳﯿﻠﻪ آﺑﮑﻨﺪﻫﺎي ﻣﻨﻄﻘﻪ ﺑﻪﺗﺮﺗﯿﺐ درﺻﺪ اﺷﺒﺎع، ﻣﻘﺪار ﺷﻦ، ﻃﻮل ﺣﻮﺿﻪ، ﻣﺴﺎﺣﺖ ﺣﻮﺿﻪ و ﺿﺮﯾﺐ ﮔﺮدي ﺑﻪﺗﺮﺗﯿﺐ ﺑﯿﺸﺘﺮﯾﻦ ﺗﺄﺛﯿﺮ را در ﺑﺮآورد ﻫﺪررﻓﺖ ﺧﺎك داﺷﺘﻨﺪ ﮐﻪ وارد ﻣﻌﺎدﻟﻪ ﭘﯿﺶ ﺑﯿﻨﯽ ﻫﺪررﻓﺖ ﺧﺎك ﺷﺪﻧﺪ.

Recognition of influential factors is required for management of gully erosion. The purpose of this study was gully classification and determining the most effective variables on the soil loss in the Fath Abad, Buin Zahra in Qazvin Province. Twenty four gullies were selected, surveyed and recorded by GPS, and their morphologic characteristics including length, width and depth were measured. Surface soil samples were taken from headcut and were analyzed for texture, EC, pH, organic matter and some anions and cations. Indices related to the form of watershed were extracted from the digital elevation model which derived from UAV image processing. The Ward method was used for cluster analysis of gullies and their properties. Factor analysis, the correlation between factors and multivariate regression were performed to determine important and effective factors on the formation of gullies in SPSS. The results of the research indicated that gullies have vertical headcuts, trapezoidal cross-sections and linear general plans. The average depth of headcuts, depth at 50% of the gully length and the average gully length were 0.4, 0.6 and 25 m, respectively. Soil texture was loam and average soil texture components including sand, silt and clay were 30, 46 and 24%, respectively. The mean EC and pH of the samples was 8 dSm-1 and 8.4 respectively. Linear correlation between the total volume of soil loss and other gully characteristics showed that the average cross section, average gully lower width and upper width, sand content, average gully depth and total length have meaningful correlation coefficients greater than 0.6 at 1% percent level. Also, multivariate regression results showed that the most effective factors on soil loss by gully erosion were saturation percentage, sand content, roundness coefficient, basin length and area respectively, which had more effect on soil loss prediction, which entered into the loss prediction equation.