استفاده از مدل‌هاي آماري و هيدروشيميايي در تحليل كيفي منابع آب زيرزميني (مطالعه موردي: دشت مهربان آذربايجان‌شرقي)

Using Statistical and Hydrochemical Models for Qualitative Analysis of Groundwater Resources (Case Study: Mehraban plain, In East Azerbaijan

دشت مهربان در استان آذربايجان­شرقي ايران، 60 كيلومتري شرق تبريز، واقع شده ­است و منابع آب زيرزميني ﺗﻤﺎﻣﯽ آب ﺷــﺮب و ﻗﺴــﻤﺖ ﻋﻤﺪه اي از آب ﻣﺼــﺮﻓﯽ ﮐﺸــﺎورزي آن را ﺗﺎﻣﯿﻦ ﻣﯽﮐﻨﺪ. اﯾﻦ ﻣﻨﺎﺑﻊ ﺗﺤﺖ ﺗﺄﺛﯿﺮ ﺳــﺎزﻧﺪﻫﺎي زﻣﯿﻦﺷـــﻨﺎﺳـــﯽ، ﺗﺒﺨﯿﺮ زﯾﺎد از آب زﯾﺮزﻣﯿﻨﯽ و ﺗﻐﺬﯾﻪ از رودﺧﺎﻧﻪﻫﺎي ﺷـــﻮر و ﺑﺮداﺷـــﺖ ﺑﯿﺶ از ﺣﺪ از آب زﯾﺮزﻣﯿﻨﯽ ﺑﺎ اﻓﺰاﯾﺶ ﺷــﺪﯾﺪ ﻣﻘﺪار ﺷــﻮري ﻣﻮاﺟﻪ اﺳــﺖ. ﻃﻮري ﮐﻪ ﻣﯿﺰان ﻫﺪاﯾﺖ اﻟﮑﺘﺮﯾﮑﯽ در ﻗﺴــﻤﺖﻫﺎي ﻏﺮﺑﯽ دﺷــﺖ ﻣﺨﺼــﻮﺻــﺎ در روﺳــﺘﺎي ارﺑﻄﺎن ﺑﻪ 9800 ﻣﯿﮑﺮوزﯾﻤﻨﺲ ﺑﺮ ﺳــﺎﻧﺘﯽﻣﺘﺮ ﻧﯿﺰ ﻣﯽرﺳــﺪ. ﺑﻨﺎﺑﺮاﯾﻦ در ﻣﻄﺎﻟﻌﻪ ﺣﺎﺿــﺮ ﺳــﻌﯽ ﺷــﺪه اﺳــﺖ ﺗﺎ ﺑﺎ اﺳـﺘﻔﺎده از روشﻫﺎي آﻣﺎري و ﻣﺪلﻫﺎي ﻫﯿﺪروﺷـﯿﻤﯿﺎﯾﯽ ﻣﻨﺸﺄ ﺷﻮري آب ﻫﺎي زﯾﺮزﻣﯿﻨﯽ و ﺗﺄﺛﯿﺮ ﺳﺎزﻧﺪﻫﺎي زﻣﯿﻦﺷﻨﺎﺳﯽ ﺑﺮ ﮐﯿﻔﯿـﺖ ﻣﻨـﺎﺑﻊ آب ﻣﻨﻄﻘـﻪ، ﺗﻌﯿﯿﻦ ﮔﺮدد. ﺑـﺪﯾﻦ ﻣﻨﻈﻮر 22 ﻧﻤﻮﻧـﻪ آب از ﭼﺎه ﻫﺎي ﻋﻤﯿﻖ و ﻧﯿﻤﻪﻋﻤﯿﻖ ﻣﻨﻄﻘﻪ ﻣﻮرد ﻣﻄﺎﻟﻌﻪ در ﻣﻬﺮﻣﺎه ﺳـﺎل 1392 ﺟﻤﻊآوري و در آزﻣﺎﯾﺸـﮕﺎه آب ﺷـﻨﺎﺳﯽ داﻧﺸ ﮕﺎه ﺗﺒﺮﯾﺰ ﺗﺠﺰﯾﻪ ﮔﺮدﯾﺪ. وﺿﻌﯿﺖ ﻫﯿﺪروژﺋﻮﺷﯿﻤﯿﺎﯾﯽ اﯾﻦ ﻣﻨﺎﺑﻊ ﺑﺎ اﺳـﺘﻔﺎده از روش ﺗﺤﻠﯿﻞ ﻣﺆﻟﻔﻪ ﻫﺎي اﺻﻠﯽ ﻣﻮرد ﺑﺮرﺳﯽ ﻗﺮارﮔﺮﻓﺖ. ﺑﺮاﺳﺎس روش ﺗﺤﻠﯿﻞ ﻋﺎﻣﻠﯽ، 84/85 درﺻﺪ از ﺗﻐﯿﯿﺮات ﮐﯿﻔﯽ آب ﺗﻮﺳـﻂ ﺳـﻪ ﮔﺮوه ﻋﺎﻣﻠﯽ ﮐﻨﺘﺮل ﻣﯽ ﺷـﻮد. ﺑﻪ ﻣﻨﻈﻮر ﺷﻨﺎﺳﺎﯾﯽ ﻓﺮآﯾﻨﺪﻫﺎي ژﺋﻮﺷﯿﻤﯿﺎﯾﯽ ﺣﺎﮐﻢ ﺑﺮ آﺑﺨﻮان، ﻧﻤﻮدارﻫﺎي ﺗﺮﮐﯿﺒﯽ، ﻧﺴــﺒﺖﻫﺎي ﯾﻮﻧﯽ و اﻧﺪﯾﺲﻫﺎي اﺷــﺒﺎع ﮐﻠﺴــﯿﺖ، دوﻟﻮﻣﯿﺖ و ژﯾﭙﺲ ﻧﻤﻮﻧﻪ ﻫﺎ ﻣﻮرد ارزﯾﺎﺑﯽ ﻗﺮار ﮔﺮﻓﺖ. ﻧﺘﺎﯾﺞ ﻧﺸـﺎن داد ﮐﻪ ﺗﺮﮐﯿﺐ ﺷﯿﻤﯿﺎﯾﯽ آب زﯾﺮزﻣﯿﻨﯽ ﺑﻪ ﺷﺪت ﺗﺤﺖ ﺗﺄﺛﯿﺮ ﺗﻐﺬﯾﻪ از رودﺧﺎﻧﻪ، رﺳﻮﺑﺎت ﺗﺸﮑﯿﻞ دﻫﻨﺪه آﺑﺨﻮان و ﺗﺒﺨﯿﺮ از آب زﯾﺮزﻣﯿﻨﯽ ﻗﺮار ﮔﺮﻓﺘﻪ اﺳـــﺖ. ﻧﺘﺎﯾﺞ ﻧﻤﻮدارﻫﺎي ﺗﺮﮐﯿﺒﯽ ﻧﺸـــﺎن داد ﮐﻪ ﻓﺮآﯾﻨﺪﻫﺎﯾﯽ ﻧﻈﯿﺮ اﻧﺤﻼل ﻫﺎﻟﯿﺖ، ژﯾﭙﺲ، دوﻟﻮﻣﯿﺖ و ﺗﺒﺎدل ﯾﻮﻧﯽ ﮐﯿﻔﯿﺖ ﺷﯿﻤﯿﺎﯾﯽ آب زﯾﺮزﻣﯿﻨﯽ را ﺗﺤﺖ ﺗﺄﺛﯿﺮ ﻗﺮار ﻣﯽدﻫﻨﺪ.

Mehraban Plain is located in the East Azarbaijan province of Iran, 60 kilometers from east of Tabriz, where groundwater resources supply its entire drinking and most of agricultural water demands. These resources are highly saline due to the effect of salty geological formations, high evaporation from groundwater resources and recharge of saline water from rivers and high withdrawal from fresh groundwater. As a result, the electrical conductivity of groundwater in the western parts of the plain, especially in the Arbatan village, is reached to about 9800 μmhos cm-1. So, it is tried to use statistical and hydrochemical methods to determine sources of groundwater salinity and the effect of geological formation on the water quality of the study area. In this research 22 water samples were collected from deep and shallow abstraction wells and were chemically analyzed in hydrology lab of the Tabriz University. Hydrochemical conditions of the resources were analyzed by multivariate statistical methods. According to the factor analyzing methods, 84.85 percent of chemical variations are controlled by three groups of factors. For identifying, governing geochemical processes in the aquifer composite diagrams, ions ratios and saturation index of calcite, dolomite and gypsum were evaluated. The results showed that the chemical compositions of groundwater were highly effected by recharge from the rivers, sediments of the aquifer and evaporation from the groundwater. The composite diagrams results showed that the processes such as halite, gypsum and dolomite solution and ion exchange phenomenon affect the groundwater chemical quality