Abstract <p>In this study, 90 groundwater samples from the Manas River Basin were used to cluster hydrochemical datasets using self-organizing map (SOM) analysis, and the chemical characteristics and control factors of groundwater were determined by combining traditional hydrochemical analysis methods. Water quality index (WQI) and irrigation index (sodium adsorption ratio, residual sodium carbonate, permeability index, potential salinity, and soluble sodium percentage) were used to evaluate groundwater quality and irrigation suitability. The SOM clustering method divides 10 hydrochemical parameters into six clusters. The main hydrochemical types are HCO₃–Na (Cluster 1), HCO₃–Ca (Clusters 2 and 4), and Cl–Na (Clusters 3, 5, and 6). Rock (silicate and carbonate) weathering, evaporation, and cation exchange are the main factors affecting groundwater chemistry. The results of the water quality evaluation show that the proportions of good and medium water samples are 52 and 30%, respectively, and that most of the groundwater samples meet the drinking requirements. The results of the irrigation suitability evaluation showed that only Cluster 2 water samples can be used for irrigation without special measures. These results provide a basis for the effective management and utilization of groundwater resources in the Manas River Basin.</p>