Evaluation and Zoning of Groundwater Quality for Agricultural Purposes in Gonabad Plain Arid Region

Document Type : Original Article

Authors

Department of Water and Environmental Engineering, Faculty of Civil Engineering, Shahrood University of Technology, Shahrood, Iran

10.22044/jhwe.2025.15626.1050

Abstract

Groundwater is one of the most important water resources for human society, particularly in arid and semi-arid regions. It is estimated that groundwater supplies 34% of drinking water, 42% of irrigated agricultural water, and 24% of direct industrial use worldwide. In arid regions, where average rainfall is significantly low and its distribution is uneven, groundwater plays a crucial role in agricultural water supply. This aim of this work is to evaluate the groundwater quality of the Gonabad Plain in the Khorasan Razavi Province for agricultural purposes using the standards of the Food and Agriculture Organization (FAO); the standards of the Iranian Institute of Standards and Industrial Research, irrigation indices, and the Wilcox classification over a 15-years period. For this purpose, 10 chemical parameters of water including calcium, magnesium, sodium, sodium adsorption ratio (SAR), Electrical Conductivity (EC), Total Dissolved Solids (TDSs), pH, bicarbonate, chloride, and sulfate were analyzed between 2007 and 2022 in 16 wells within the plain. Based on the FAO standards, two parameters of electrical conductivity and magnesium exceeded the permissible limits. According to irrigation indices, the water was classified as unsuitable for drip and sprinkler irrigation, due to certain limitations. Furthermore, based on the Wilcox classification, 31.25% of the wells contained water of medium quality for agricultural use, while the rest were deemed unsuitable, requiring remedial measures.

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