Assessment of Groundwater Chemical Quality, Using Inverse Distance Weighted Method

Abstract

An interpolation technique, ordinary Inverse Distance Weighted (IDW), was used to obtain the spatialdistribution of groundwater quality parameters in Damghan plain of Iran. According to Scofield guidelines for TDSvalue, of the water samples were harmful for irrigation purposes. Regarding to EC parameter, more than ofstudied area was laid in bad range for irrigation purposes. The most dominant anion was Cl- and of water samplesshowed a very hazardous class. According to Doneen guidelines for chloride value, of collected water from theaquifer had slight to moderate problems for irrigation water purposes. The predominant cations in Damghan plainaquifer were according to Na+> Ca++> Mg++> K+. Sodium ion was the dominant cation and regarding to Na+ contentguidelines, almost all groundwater samples had problem for foliar application. Calcium ion distribution was within usualrange. The magnesium ion concentration is generally lower than sodium and calcium. The majority of the samples showedMg++amount within usual range. Also K+ value ranged from to meq/L and all the water samples had potassiumvalues within the permissible limit. Based on SAR criterion % of collected water had slight to moderate problems. TheSSP values were found from to . According to SAR value, thirty percent of ground water samples weredoubtful class. The estimated amounts of RSC were ranged from - and based on RSC criterion, twenty percent ofgroundwater samples had slight to moderate problems.