Classification of groundwater types in Pakokku district in central Myanmar

This study aimed to undertake a comprehensive hydrogeological and hydrochemical assessment of groundwater in the Pakokku area, Central Myanmar, to classify water types, identify dominant hydrochemical facies and evaluate suitability for irrigation under arid conditions.

Groundwater samples from 17 bore wells, representing alluvial and Irrawaddy aquifers, were analysed. Field parameters (pH, temperature, EC, TDS) were measured in situ, and major ions were determined using standard laboratory methods. Hydrochemical facies were interpreted using Piper and Chadha diagrams, while irrigation suitability was assessed through indices (SAR, SSP, RSBC, MAR, PS, KR, PI) and Richards and Wilcox diagrams.

Results indicate two dominant facies: Ca–Mg–Cl–SO₄ and Ca–Mg–HCO₃, with 82% of samples belonging to the former, reflecting carbonate and silicate weathering. EC ranges from 480–1100 μS/cm and TDS from 310– 715 ppm, indicating fresh to slightly mineralised water. SAR values (0.99– 2.04) and SSP (<40%) classify most samples as excellent to good. Most waters fall within C2–S1 and C3–S1 fields, showing moderate salinity and low sodium hazard.

Overall, the groundwater of 14 of 17 samples is suitable for irrigation, while three show elevated salinity or magnesium hazard. Groundwater in general is assessed as fresh, stable and suitable for sustainable agricultural use with proper salinity management.

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