Hydrochemical assessment of water quality for irrigation: a case study of the Medjerda River in Tunisia

In order to characterize, classify and evaluate the suitability of Medjerda River water for irrigation, a hydrochemical assessment was conducted. It accounts for 80 % of the total Tunisian surface water. In this paper, hydrographical methods and PHREEQC geochemical program were used to characterize water quality of Medjerda River, whereas its suitability for irrigation was determined in accordance with its electrical conductivity (EC), sodium adsorption ratio (SAR) and sodium concentrations. It was established that the water samples were undersaturated with calcite, dolomite, aragonite, anhydrite, gypsum and halite except in one water sample which is supersaturated with carbonate minerals. The quality assessment of Medjerda River for irrigation purposes showed that some points belonged to the excellent-to-good and good-to-permissible irrigation water categories, while the remaining ones were classified as doubtful to unsuitable for irrigation making the river water use limited to plants with high salt tolerance. Moreover, based on FAO guidelines, almost all water samples may cause immediate salinity to gradual increasing problem but no soil infiltration problems except for two sampling points. However, immediate development or possible increasing of severe toxicity problems may be caused by the continuous use of this water for irrigation due to troublesome concentrations of chloride and sodium. © 2015, The Author(s).