Chloride Estimation in Ground Water From Electrical Conductivity Measurement

Abstract

Salinity assessment of ground waters for the irrigation purpose often includes measurement of chloride ion, constitute that in large concentrations is toxic to plant. Since the measurement of electrical conductivity is much easier than determining chloride ion, the aim of this study was to develop an empirical relationship between chloride ion concentration and electrical conductivity of ground waters for western of Iran. Large numbers of water samples, 1063 laboratory and 2252 field data, were collected over about 66000 Km 2 areas in west of Iran. Electrical conductivity (EC) was measured with a conductivity cell and Cl-concentration by titration with AgNO 3 solution. The data were grouped into various groups based on crop tolerance to salinity and consequently to EC. Linear, polynomial and power regression models were tested. Using data for all 3315 samples, all three models were highly significant and explained 99% of the variability in observed Cl-values. Other models for different groups of data also developed and it was concluded that there is a good agreement and correlation between EC and Cl-concentration in water samples except for EC<3 dSm-1 .