ASSESSMENT OF GROUNDWATER QUALITY FOR IRRIGATION PURPOSES: A CASE STUDY OF SUWANNAPHUM DISTRICT, ROI-ET, THAILAND

Abstract

Groundwater was used to increase water usage and solve the problem of an inadequate irrigation system in Suwannaphum district, Roi-Et, Thailand. Groundwater from shallow wells and deep ponds was used in this area. This study aims to determine groundwater quality for irrigation concerning its physicochemical properties and then classify it for irrigation purposes. The hydrochemical parameters, namely pH, Electrical conductivity (EC), Total dissolved solids (TDS), Sodium adsorption rate (SAR), Sodium percentage (Na%), Kelly’s index (KI), Residual sodium carbonate (RSD), and Magnesium hazard (MH) were calculated and discussed thoroughly in US Salinity, Wilcox and Gibbs diagrams. The abundance of cation and anion are Na+>Ca2+>Mg2+>K+=Cl->HCO32-. Most of the groundwater samples are suitable for irrigation. The majority of groundwater samples are subject to medium salinity with low alkalinity (US Salinity diagram), while the Wilcox diagram classified the water as excellent to doubtful for irrigation. However, groundwater samples from shallow wells in the area of Ban Nong I Khem and Ban Tang Mung were found to have high EC, TDS, and ion values greater than those recommended by the irrigation guidelines. The halite dissolution caused sodium and chloride element in groundwater. Moreover, agricultural activities (use of geochemical) can help increase the value of sodium in the study area. Therefore, problematic and require high salt toleration of crops and special irrigation management methods.