تحلیل روش های زمین آماری در پایش مکانی وضعیت شوری و سدیمی خاک های تحت آبیاری با پساب تصفیه شده شهری

نوع مقاله: مقاله پژوهشی

نویسنده

استادیار دانشکده آب و خاک دانشگاه زابل

چکیده

عدم مدیریت صحیح در استفاده از منابع طبیعی همچون خاک می­تواند باعث تخریب خصوصیات کیفی آن و متعاقباً کاهش حاصلخیزی خاک شود. این مسئله، لزوم پایش مکانی این خواص در راستای ارائه راهکارهای مطلوب مدیریتی جهت حفظ حاصلخیزی آن را نشان می­دهد. به همین منظور، در این پژوهش، به پایش مکانی خصوصیات کیفی خاک در لایه سطحی در اراضی آبیاری شده با پساب شهری با قدمتی طولانی بر اساس روش­های زمین­آماری و ارزیابی آن بر اساس محدوده استاندارد جهانی پرداخته شد. بدین منظور خصوصیات کیفی خاک شامل نسبت جذب سدیم (SAR)، درصد سدیم تبادلی (ESP)، هدایت الکتریکی (EC) و واکنش خاک (pH) از منطقه­ای با وسعت 190 هکتار و در پیکسل­هایی با ابعاد 150 در 150 متر برداشت شد و امکان تهیه نقشه­های رستری با روش­های میانگین متحرک وزنی (WMA)­، کریجینگ و کوکریجینگ فراهم گردید. نتایج نشان داد روش کریجینگ برای پارامتر ESP و روش WMA برای سایر پارامترها، کمترین خطای تخمین بر اساس معیارهای ارزیابی را به همراه داشت. همچنین استفاده از متغیر کمکی تأثیر مثبتی در افزایش شعاع تأثیر و افزایش دقت درون­یابی نداشت. مقایسه نقشه­های رستری تهیه‌شده بر اساس روش­های منتخب با حدود استاندارد اداره  شوری ایالات‌متحده آمریکا نشان داد، مصرف بدون مدیریت منابع آب نامتعارف در این منطقه باعث شور شدن بیش از 97 درصد از کل منطقه شده است. همچنین خطر وجود سدیم در بیش از 94 درصد از کل منطقه  مشکلات خاک­های منطقه را دوچندان کرده است. این امر می­تواند با تخریب ساختمان خاک، خسارات جبران­ناپذیری را در شرایط بحران شدید آب به همراه داشته باشد. لذا کشاورزی پایدار و امنیت غذایی در منطقه مطالعاتی مستلزم ارائه راهکارهای مدیریتی جهت اصلاح خاک همچون آبشویی در فصل غیر کشت و یا آبیاری ترکیبی با آب سالم در جهت حفظ منافع اقتصادی و محیط‌زیست طبیعی است.

کلیدواژه‌ها


عنوان مقاله [English]

Analyzing the Geostatistical Methods in Spatial Monitoring of Saline and Sodic Condition of Soils under Treated - Wastewater Irrigation

نویسنده [English]

  • Fatemeh Karandish
Assistant Professor, Department of Water Engineer, Faculty of Soil and Water, Zabol University, Iran. (Corresponding author)
چکیده [English]

Unmanaged use of natural resources such as soil would lead to deterioration of its quality and fertility. Consequently, spatial monitoring of these properties is necessary to find the optimal management options to protect soil fertility. Thus, in this study, the long-term effects of treated wastewater irrigation on qualitative properties of surface soil layer were spatially monitored using geostatistical methods and were compared with worldwide standards. Consequently, the soil qualitative properties including sodium adsorption ratio (SAR), exchangeable sodium percentage (ESP), electrical conductivity (EC) and acidity (pH) was analyzed in pixels with 150×105 meter dimension and the possibility of extracting raster maps using weighting moving average (WAM), kriging and co-kriging methods was investigated. Results showed that kriging and WMA had the least estimation error for ESP and the other parameters, respectively, based on the evaluating indices. Also using covariates does not have positive effect on increasing range of influence and interpolation accuracy. Comparing the prepared raster maps by the selected method with the standard values of Soil Survey Manual of USA showed that unmanaged use of unconventional water caused more than 97% of the study area to have saline soils. Also, hazard of sodium in the soils dominated to salinity problem in more than 94% of the study area. These could have irreparable damages under water crisis through degrading soil structure. In conclusion, for sustainable agriculture and food security in the study area it is necessary to offer management options for soil improvement such as leaching in uncultivated seasons or combined irrigation with fresh water to protect economic and environmental issues

کلیدواژه‌ها [English]

  • Spatial monitoring
  • Saline soil
  • Sodic soil
  • Sustainable agriculture
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