Groundwater quality assessment and its suitability for agricultural purposes in the Behbahan Plain, SW Iran

Abstract

Abstract Groundwater is the main agricultural water resource in arid and semi-arid regions, so, preserving it is extremely important. In this study, groundwater quality was assessed for irrigation, using the principal chemical and physical quality parameters from 30 wells in the study area. Groundwater classification on the basis of electrical conductivity reveals that more than 85% of the samples taken fall into the ‘unsuitable’ and ‘doubtful’ classes. On the basis of Richards's classification, 67% of the samples are unsuitable for irrigation. Most, however, appear suitable for irrigation based on their sodium adsorption ratio, %Na, permeability index, magnesium adsorption ratio, Kelly's ratio and residual sodium carbonate water quality indices. The concentration of boron varies between 0 and 2 mg/l, within the FAO's (Food and Agriculture Organization of the United Nations) acceptable standard range. About 60% of the wells are not suitable for drip irrigation because of the water's potential for clogging. There will be no water infiltration problem, if groundwater in the study area is used for irrigation. With respect to the SO42− and Cl− concentrations, 53% and 13% of the samples collected are unsuitable for irrigation, respectively. Less than 10% of the samples have ‘severe’ constraints restricting their use for irrigation with respect to nitrogen. For sprinkler irrigation, however, the groundwater is subject to ‘severe’ restrictions. Geochemical investigations indicate that the water chemistry is affected by processes including evaporation, water-rock interactions and human activities.