رفتار آب عبوري از ستون هاي حاوي لايه هاي رس مونتموريلونايت

Behavior of Water through Soil Columns Containing Montmorillonite Clay Layers

زﻣﯿﻨﻪ و ﻫﺪف: در ﻣﻄﺎﻟﻌﺎت ﻫﯿﺪروﻟﻮژي، ﺣﻔﺎﻇﺖ و ﻣﺪﯾﺮﯾﺖ آب، اﻃﻼع دﻗﯿﻖ از ﻣﯿﺰان ﻇﺮﻓﯿﺖ آﺑﯽ ﺧﺎكﻫﺎي ﻣﺨﺘﻠﻒ و ﺳﺮﻋﺖ ﻧﻔﻮذ آب ﺑﻪﻣﻨﻈﻮر اﺟﺮاي ﭘﺮوژهﻫﺎي آﺑﯿﺎري و زﻫﮑﺸﯽ و ﮐﻨﺘﺮل ﻓﺮﺳﺎﯾﺶ ﺧﺎك در ﺣﻮﺿﮥ آﺑﺨﯿﺰ ﺿﺮوري اﺳﺖ. ﻫﺪف از اﯾﻦ آزﻣﺎﯾﺶ ﺑﺮرﺳﯽ ﺗﺎﺛﯿﺮ ﻻﯾﻪ رﺳﯽ در اﻧﺘﻘﺎل ﺣﺠﻢ آب ﻋﺒﻮري در ﺧﺎك ﺷﻦﻟﻮﻣﯽ اﺳﺖ روش ﺑﺮرﺳﯽ: ﺑﺪﯾﻦﻣﻨﻈﻮر در ﺳﺘﻮنﻫﺎﯾﯽ ﺑﻪ ارﺗﻔﺎع 150 ﺳﺎﻧﺘﯽﻣﺘﺮ و ﻗﻄﺮ 15 ﺳﺎﻧﺘﯽﻣﺘﺮ ﺑﺎ ﺑﺎﻓﺖ ﺷﻦﻟﻮﻣﯽ ﮐﻪ داراي ﻻﯾﻪﻫﺎي رﺳﯽ در داﺧﻞ ﺳﺘﻮن ﺑﻪ ﻋﻤﻖﻫﺎي 13 و 20 ﺳﺎﻧﺘﯽﻣﺘﺮ ﮔﺬاﺷﺘﻪ ﺷﺪ و ﺗﯿﻤﺎرﻫﺎﯾﯽ ﺑﻪﻋﻨﻮان ﺷﺎﻫﺪ ﺑﺪون ﻻﯾﻪ رﺳﯽ در ﻧﻈﺮ ﮔﺮﻓﺘﻪ ﺷﺪ. ﺣﺠﻢﻫﺎي آب ﻣﺸﺨﺺ و ﯾﮑﺴﺎﻧﯽ ﺑﺎ ﻏﻠﻈﺖﻫﺎي ﻣﺨﺘﻠﻒ ﻧﻤﮏ، ﺑﻪ ﻫﻤﻪ ﺳﺘﻮنﻫﺎ داده ﺷﺪ و ﻧﻤﻮﻧﻪﮔﯿﺮي ﺣﺠﻢ آب ﺧﺮوﺟﯽ از ﺳﺘﻮنﻫﺎ روزاﻧﻪ اﻧﺠﺎم ﺷﺪ. ﯾﺎﻓﺘﻪﻫﺎ: ﻧﺘﺎﯾﺞ ﻧﺸﺎن داد ﮐﻪ ﻻﯾﻪ رﺳﯽ ﺑﻪﺧﻮﺑﯽ ﺗﻮاﻧﺴﺘﻪ ﺣﺠﻢ آب ﻋﺒﻮري از ﺳﺘﻮن را ﮐﺎﻫﺶ دﻫﺪ و ﺑﺎ اﻓﺰاﯾﺶ ﺿﺨﺎﻣﺖ ﻻﯾﻪ رﺳﯽ ﺣﺠﻢ آب ﻋﺒﻮري ﻫﻢ ﺑﻪ ﻧﺴﺒﺖ، ﮐﺎﻫﺶ ﺑﯿﺶﺗﺮ ﻣﯽﯾﺎﺑﺪ. ﻧﺘﺎﯾﺞ ﻧﺸﺎن داد ﺑﺎ اﻓﺰاﯾﺶ ﻋﻤﻖ ﻻﯾﻪ رﺳﯽ از ﺷﺎﻫﺪ ﺑﻪ ﻋﻤﻖ 20 ﻣﻘﺪار آب ﻋﺒﻮري اوﻟﯿﻪ در ﻏﻠﻈﺖ 13 ﻣﯿﻠﯽ اﮐﯽواﻻن 16 درﺻﺪ و در ﻏﻠﻈﺖ 20ﻣﯿﻠﯽ اﮐﯽ واﻻن 35 درﺻﺪ ﮐﺎﻫﺶﯾﺎﻓﺘﻪ اﺳﺖ. ﺑﺤﺚ و ﻧﺘﯿﺠﻪﮔﯿﺮي: ﻋﻤﻠﮑﺮد ﻣﺘﻔﺎوت ﻣﻮﺟﻮد ﺑﻪ دﻟﯿﻞ وﺟﻮد ﻻﯾﻪ رس ﺑﺎ ﺿﺨﺎﻣﺖ ﻣﺘﻔﺎوت و ﺑﻮده اﺳﺖ. ﺑﺎﻓﺖ رس ﺑﻪدﻟﯿﻞ رﯾﺰ ﺑﻮدن و ﺗﺮاﮐﻢﭘﺬﯾﺮي زﯾﺎد ﻣﯽﺗﻮاﻧﺪ ﺑﺎﻋﺚ ﺗﺄﺧﯿﺮ در ﺣﺮﮐﺖ آب در ﺧﺎك ﺷﻮد ﮐﻪ از اﯾﻦ ﮐﻨﺪ ﺷﺪن اﻧﺘﻘﺎل ﻣﯽﺗﻮان ﺑﺮاي ﺟﻠﻮﮔﯿﺮي از ﺣﺮﮐﺖ ﺷﯿﺮاﺑﻪﻫﺎ و آﻟﻮدﮔﯽﻫﺎ ﺑﻪ اﻋﻤﺎق ﺧﺎك و آﻟﻮدهﮐﺮدن آبﻫﺎي زﯾﺮزﻣﯿﻨﯽ اﺳﺘﻔﺎده ﮐﺮد. ﺑﻪﻧﻈﺮ ﻣﯽرﺳﺪ ﺑﺎ ﺗﻐﯿﯿﺮ ﻋﻤﻖ ﻻﯾﻪ رﺳﯽ ﻫﺪاﯾﺖ آب ﻧﻔﻮذي ﺑﻪ ﻻﯾﻪﻫﺎي زﯾﺮﯾﻦ ﺑﺨﺼﻮص در ﻣﻨﺎﻃﻖ ﺣﺴﺎس و ﮐﺎرﺑﺮدي را ﺑﺘﻮان ﮐﻨﺘﺮل ﮐﺮد.

Background and Objective: In studies realted to hydrology, water conservation and management, accurate information of the water capacity in different soils for measuring water infiltration, drainage and erosion control is essential in order to launch irrigation projects in watersheds. The purpose of this study is to evaluate the effect of clay layers in the transfer of water through loamy sand. Method: Soil columns with a height of 150 cm and a diameter of 15 cm, were filled with clay layers to depths of 13 and 20 cm. Then the same volume of water with different salt concentrations was added to all columns. Also water sampling was carried out on a daily basis. Findings: Results showed that the layer clay could reduce the volume of water passing through the columns and by increasing the thickness of the clay layer, the ratio of passed water decreased. The results showed that by increasing the depth of the clay layer in the control treatment to a depth of 20, the amount of water at a concentration of 13 mEq and 20 mEq decreased by 16 and 35 percent. Discussion and Conclusion: Different performances were due to the thickness of clay layer. Because of the small clay texture and high compressibility, the movement of water in the soil can be delayed. This feature can be used to prevent the movement of leachate and pollution into the soil and contaminate groundwater. It seems that by changing the depth of the clay layer, the conductivity can be controlled in sensitive areas.