عوامل موثر بر کیفیت منابع آب زیرزمینی منطقه سراوان، جنوب شرق ایران

اﯾﻦ ﺗﺤﻘﯿﻖ ﺑﻪ ﻣﻄﺎﻟﻌﻪ ﻫﯿﺪروﺷﯿﻤﯽ و ﮐﯿﻔﯿﺖ ﻣﻨﺎﺑﻊ آب زﯾﺮزﻣﯿﻨﯽ در ﻣﻨﻄﻘﻪ ﺳﺮاوان، ﭘﺮداﺧﺘﻪ اﺳﺖ. ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﻫﯿﺪروﮔﺮاف ﻣﯿﺎﻧﮕﯿﻦ ﺳﻄﺢ اﯾﺴﺘﺎﺑﯽ، ﺗﺮاز ﺳﻄﺢ آب زﯾﺮزﻣﯿﻨﯽ )از ﺳﺎل 1394ﺗﺎ 1399( ﮐﺎﻫﺶ ﺣﺪودا 8ﻣﺘﺮی داﺷﺘﻪ اﺳﺖ. زﻣﺎن ﺗﺄﺧﯿﺮ ﺑﯿﻦ ﺑﺎرش و اﺛﺮ آن ﺑﺮ ﺳﻄﺢ اﯾﺴﺘﺎﺑﯽ ﺣﺪوداً ﯾﮏ ﯾﺎ دو ﻣﺎه ﻣﺤﺎﺳﺒﻪ ﺷﺪه اﺳﺖ ﮐﻪ ﻧﺸﺎن دﻫﻨﺪه ﻧﻔﻮذﭘﺬﯾﺮی ﻧﺴﺒﺘﺎ ﺧﻮب در آﺑﺨﻮان آﺑﺮﻓﺘﯽ اﺳﺖ. ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﻫﺪاﯾﺖ اﻟﮑﺘﺮﯾﮑﯽ ﺗﻐﯿﯿﺮات ﮐﯿﻔﯿﺖ آب زﯾﺮزﻣﯿﻨﯽ از ﻏﺮب ﺑﻪ ﺷﺮق در اﯾﻦ ﻣﻨﺎﻃﻖ رخ داده اﺳﺖ و آب زﯾﺮزﻣﯿﻨﯽ ﻗﻨﻮات ﮐﯿﻔﯿﺖ ﺑﻬﺘﺮی ﻧﺴﺒﺖ ﺑﻪ ﭼﺎه ﻫﺎی ﺑﻬﺮه ﺑﺮداری ﺑﺮﺧﻮردار ﻫﺴﺘﻨﺪ. زﯾﺮا از ﯾﮏ ﻃﺮف ﻣﺎدر ﭼﺎه ﻗﻨﻮات در ﻣﺤﻞ ﺑﺎﻻﺳﺖ آﺑﺨﻮان و درون ﻣﺨﺮوط اﻓﮑﻨﻪ ﻫﺎ ﮐﻪ آب ز ﯾ ﺮزﻣﯿﻨﯽ ﮐﯿﻔﯿﺖ ﺑﻬﺘﺮی دارﻧﺪ، ﺣﻔﺮ ﺷﺪه اﻧﺪ و از ﻃﺮف دﯾﮕﺮ ﺳﯿﺴﺘﻢ زﻫﮑﺸﯽ ﻗﻨﻮات ﺑﻪ ﻧﺤﻮی اﺳﺖ ﮐﻪ ﻓﻘﻂ آب ز ﯾﺮزﻣﯿﻨﯽ ﻣﺎزاد ﺑﺎﻻﺗﺮ از ﺗﺮاز دﻫﻨﻪ ﻗﻨﺎت، ﺧﺎرج ﻣﯽ ﺷﻮد و آبﻫﺎی زﯾﺮزﻣﯿﻨﯽ ﻋﻤﯿﻖﺗﺮ آﺑﺨﻮان ﮐﻪ ﺷﻮری ﺑﯿﺸﺘﺮ ی دارد را ﺧﺎرج ﻧﻤﯽﮐﻨﺪ. در آبزﯾﺮزﻣﯿﻨﯽ ﺳﻪ رﺧﺴﺎره آب nacl, naso4و nacl(hco3)وﺟﻮد دارد. ﺑﻪ ﻃﻮر ﮐﻠﯽ روﻧﺪ اﻓﺰاﯾﺶ ﻧﺴﺒﺖ درﺻﺪ ﮐﻠﺮاﯾﺪ و ﺳﺪﯾﻢ از ﻣﻨﺎﺑﻊ آب ﻗﻨﻮات ﺑﻪ ﺳﻤﺖ ﻣﻨﺎﺑﻊ آب ﭼﺎه در ﻧﻤﻮدار ﭘﺎﯾﭙﺮ ﻗﺎﺑﻞ ﻣﺸﺎﻫﺪه اﺳﺖ. ﻫﻤﭽﻨﯿﻦ اﻓﺰاﯾﺶ ﻋﻤﻖ ﭼﺎه ﻫﺎی ﺑﺮداﺷﺖ ﺳﺒﺐ اﻓﺰاﯾﺶ ﻧﺴﺒﺖ درﺻﺪ ﮐﻠﺮاﯾﺪ و ﺳﺪﯾﻢ در آب زﯾﺮزﻣﯿﻨﯽ ﺧﺮوﺟﯽ از ﭼﺎه ﺷﺪه اﺳﺖ. ﺑﺮ ﻣﺒﻨﺎی ﻧﻘﺸﻪ ﻫﺎی ﭘﺮاﮐﻨﺪﮔﯽ دﺑﯽ و ﺑﺮداﺷﺖ از آﺑﺨﻮان، ﻣﺘﻮﺳﻂ ﻣﯿﺰان ﺑﺮداﺷﺖ از ﻣﻨﺎﺑﻊ آب زﯾﺮزﻣﯿﻨﯽ در ﻏﺮب دﺷﺖ ﺑﯿﺸﺘﺮ از ﺷﺮق ﻣﻨﻄﻘﻪ ﻣﯽ ﺑﺎﺷﺪ. ﺑﺮاﺳﺎس ﺗﺤﻠﯿﻞ ﻋﺎﻣﻠﯽ، دو ﻋﺎﻣﻞ اﺻﻠﯽ ﻣﺆﺛﺮ ﺑﺮﮐﯿﻔﯿﺖ آﺑﺨﻮان ﺷﻨﺎﺳﺎﯾﯽ ﺷﺪه اﻧﺪ ﮐﻪ ﻋﺎﻣﻞ اول اﻧﺤﻼل ﮐﺎﻧﯽ ﻫﺎ ﻣﯽ ﺑﺎﺷﺪ ﮐﻪ ﮐﯿﻔﯿﺖ ﻣﻨﺎﯾﻊ آب را ﮐﻨﺘﺮل ﻣﯽ ﮐﻨﺪ و ﻋﺎﻣﻞ دوم ﻋﻮاﻣﻞ ﮐﻨﺘﺮل ﮐﻨﻨﺪه اﺳﯿﺪﯾﺘﻪ/ﻗﻠﯿﺎﺋﯿﺖ ﻣﻨﺎﺑﻊ آب ﻣﯽ ﺑﺎﺷﺪ. اﮐﺜﺮ ﻧﻤﻮﻧﻪ ﻫﺎی آب زﯾﺮزﻣﯿﻨﯽ ﻧﺴﺒﺖ ﺑﻪ اﻧﯿﺪرﯾﺖ، ژﯾﭙﺲ، آراﮔﻮﻧﯿﺖ و ﻫﺎﻟﯿﺖ ﺗﺤﺖ اﺷﺒﺎع و آب زﯾﺮزﻣﯿﻨﯽ ﺗﻤﺎﯾﻞ ﺑﻪ ﺣﻞ ﮐﺮدن اﯾﻦ ﺳﻪ ﮐﺎﻧﯽ دارد. اﮐﺜﺮ ﻧﻤﻮﻧﻪ ﻫﺎ ﻧﺴﺒﺖ ﺑﻪ ﮐﻠﺴﯿﺖ و دوﻟﻮﻣﯿﺖ ﻓﻮق اﺷﺒﺎع و اﺷﺒﺎع و اﯾﻦ ﮐﺎﻧﯽﻫﺎ ﺗﻤﺎﯾﻞ ﺑﻪ ﺗﻪﻧﺸﺴﺖ در ﻣﻨﻄﻘﻪ ﻣﻮرد ﻣﻄﺎﻟﻌﻪ دارﻧﺪ.

the effective factors on the groundwater quality in the saravan area, south iran

this research has studied the hydrochemistry and quality of groundwater resources in saravan area. according to the hydrograph of the water table, ground water level (from 2014 to 2019) has decreased ( 7.88 m). the delay time between rainfall and water table is about one or two months, which indicates relatively good permeability in the alluvial aquifer. according to the ec map, the quality of groundwater has decreased from west to east, and the groundwater of qanat's has better quality than the exploitation wells. because the well's mother of the qanats is dug in the upstream part of the aquifer and inside the alluvial fan, which has better quality ground water, also the drainage system of the qanats is in such a way that only the over flow of ground water comes out. in the groundwater of the studied areas, there are three types of water: nacl, naso4 and nacl (hco3). in general, there is an increase in chloride and sodium from qanat water resources to wells in the studied area. also, increasing the depth of the well has increased the percentage of chloride and sodium. according to the distribution map of discharge of wells, groundwater extraction in the west area is more than the east region. based on the factor analysis, two main factors affecting the quality of the aquifers have been identified, the first factor is the dissolution of minerals, which controls the quality of water sources and the second factor is the factors controlling the acidity/alkalinity.