ارزیابی کیفی منابع آب زیرزمینی دشت ایذه در استان خوزستان
خشایار پیغان
1
(
دانشجوی دکتری، گروه مهندسی آبیاری و آبادانی، دانشکدگان کشاورزی و منابع طبیعی، دانشگاه تهران، کرج، ایران.
)
پیوند پاپن
2
(
دکتری خاکشناسی، کارشناس سازمان آب و برق خوزستان، اهواز، ایران.
)
مسعود صادقی میانرودی
3
(
دکتری خاکشناسی، شرکت بهره‌برداری از شبکه‌های آبیاری کرخه و شاوور، اهواز، ایران.
)
کلید واژه: آب شرب, نمودار شولر, آب آبیاری, نمودار استیف, نمودار پایپر, نمودار ویلکاکس,
چکیده مقاله :
افزایش مصرف آب سبب کاهش کیفیت و کمیت آب‌های قابل استحصال شده و بنابراین ارزیابی دقیق منابع موجود جهت پاسخ به تقاضای بخش‌های مختلف ضروری است. این پژوهش با هدف ارزیابی کیفیت منابع آب زیرزمینی دشت ایذه در استان خوزستان انجام شد. برای این هدف، از نمودارهای پایپر و استیف جهت تعیین تیپ نمونه‌ها و از نمودارهای ویلکاکس و شولر جهت ارزیابی کیفیت نمونه‌ها برای مصارف کشاورزی و شرب استفاده شد. مطابق نمودار پایپر، تیپ بیش‌تر نمونه‌های آب زیرزمینی دشت ایذه بی‌کربنات، کربنات کلسیم و بی‌کربنات منیزیم می‌باشد. آب زیرزمینی مورد مطالعه بر اساس نمودار استیف در چهار دسته قرار می‌گیرد؛ 1) آب تغذیه از سازند آهک آسماری، 2) آب زیرزمینی آلوده شده، 3) آب زیرزمینی در تماس با سازند گچساران و 4) آب تغذیه‌ای از سازند آهکی ایلام-سروک. بر اساس نمودار ویلکاکس بیش‌تر نمونه‌های آب در رده C2-S1 قرار گرفتند که جهت مصارف کشاورزی مناسب است. اما آب تعدادی از چاهها از این محدوده خارج شده و در رده‌های S1-C3، S2-C4،S1 -C4 و S2-C3 قرار گرفت. موقعیت مکانی چاهها آشکار می‌سازد که کیفیت آب در نواحی مرکزی دشت، حد فاصل دریاچه‌های میانگران و بندان، نسبت به سایر نواحی پایین‌تر است. بنابراین جهت کشاورزی در این نواحی، اعمال تمهیدات مدیریتی از جمله کشت محصولات مقاوم به شوری، انجام آبشویی و زهکشی ضروری است. مطابق نمودار شولر، کیفیت آب زیرزمینی منطقه برای مصارف شرب در رده خوب قرار دارد. با این وجود، در بخش شرب که ارتباط مستقیم با سلامت افراد دارد، انجام آزمایش‌های بیش‌تر و اعمال فرآیندهای تصفیه الزامی است.
چکیده انگلیسی :
IntroductionAlarming population growth and socio-economic development have increased the demand for water, energy and food, and challenged the sustainability of resources worldwide. In Iran, the availability of water resources has decreased drastically due to increased demand and prolonged periods of drought. In areas where surface water is limited or not easily accessible, groundwater resources are the largest fresh water reserves. Indiscriminate extraction of well water and the expansion of agricultural and industrial activities, along with climate change and numerous droughts, have caused changes in the quality of groundwater in many areas. Khuzestan province in the southwest of Iran, which is located in special geographical and hydrological conditions, has the largest share of fresh water and agricultural activity in Iran. The insufficiency of surface water resources to meet the demand in different sectors, and the increase in the use of nitrogen fertilizers in agricultural lands has caused an increase in the extraction of groundwater in the province and has put these resources at risk of pollution. This research was conducted with the aim of evaluating the quality of groundwater resources of Izeh plain in the northeast of Khuzestan province for various uses.Material and MethodsThe studied area with an area of 388 km2 is located in the northeast of Khuzestan province. There are two types of aquifers in the study area, one is an alluvial aquifer and the other is a karst aquifer. In recent years, the contamination of alluvial sediments of the plain with bacteria has caused the water extraction from wells to be stopped and more studies and researches have to be done in this field. For this purpose, 19 observation wells have been dug in different parts of the plain. The measured parameters included calcium, magnesium, sodium, potassium, chlorine, bicarbonate, sulfate, sodium absorption ratio, electrical conductivity, acidity and total dissolved solids. In this research, the Piper diagram was used to identify the type of water, the Stiff diagram was used for the hydrochemical analysis of water samples, the Wilcox diagram was used to determine the quality of groundwater for agricultural purposes, and the Schoeller diagram was used for drinking purposes. Water quality graphs were drawn with HydroChem and GWW software.Results and DiscausionAccording to Piper diagram, most types of groundwater samples in Izeh plain are bicarbonate, calcium carbonate and magnesium bicarbonate. Groundwater samples in parts of the alluvial aquifer of Izeh Plain, which are fed by Asmari and Ilam-Seruk limestones and are far enough from the city, show the calcium bicarbonate type, and in the central parts of the plain, it varies from calcium bicarbonate to magnesium bicarbonate. Based on the Stiff diagrams, Izeh groundwater samples can be classified into four categories. The first category includes wells E1, E5, E9, E12, E13, E14, E16, E17, E18, E20 and E21 (feeding water from the Asmari limestone formation), the second category includes wells E4, E6 and E22 (contaminated groundwater), the third category includes wells E7, E10 and E11 (groundwater in contact with Gachsaran formation) and the fourth category includes wells E3 and E15 (feeding water from Ilam-Sarvak limestone formation). According to the Wilcox diagram, the water of wells E1, E3, E12, E13, E16, E17 and E18 in the category S1-C2, the water of wells E6, E9 and E22 in the category S1-C3, as well as the water of wells E7, E10 and E11 respectively in the categories S2-C4, S1-C4 and S2-C3 are. In total, in terms of salinity hazard, the water of seven wells is in the medium range, four wells are in the high range and only two wells are in the very high range. The groundwater of the studied area has suitable conditions in terms of alkalinity, so that the water of 11 wells has a low hazard of alkalinity and only the water of two wells has a medium hazard of alkalinity. The analysis of the Wilcox diagram based on the wells location shows that the water quality in the central areas of the plain, between Miangaran and Bandan lakes, is lower than in other areas. According to Schoeller diagrams, the water quality of all the wells for consumption in the drinking sector is in the good category, and only one well's water is in the good to moderate suitable category. In the water of this well, the level of magnesium element is high, and this is the reason why it is out of the good category.ConclusionConsidering the importance of monitoring the quantity and quality of groundwater resources, especially in arid and semi-arid areas, this research was conducted with the aim of evaluating the quality of groundwater in the northeast of Khuzestan province. According to the Piper diagram, the type of most of the groundwater samples of Izeh plain is bicarbonate, calcium carbonate and magnesium bicarbonate. According to the Stiff diagrams, the groundwater of the studied aquifer is classified into four categories; 1) Feed water from Asmari limestone formation, 2) Contaminated groundwater, 3) Groundwater in contact with Gachsaran formation and 4) Feed water from Ilam-Sarvak limestone formation. The analysis of the Wilcox diagram of the wells based on the wells location shows that the water quality in the central areas of the plain, between Miangaran and Bandan lakes, is lower than in other areas. Therefore, for agriculture in these areas, it is necessary to apply management measures such as the cultivation of salinity-resistant crops, leaching and drainage. According to Schoeller diagrams, the plain groundwater quality is in the good category for drinking purposes. Groundwater sources are sometimes used as drinking water without purification processes, because they are considered safe for human consumption. However, in the drinking sector, which is directly related to people's health, it is necessary to conduct more tests and apply treatment processes.
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