Hydrochemical characterization and irrigation suitability of the Ganges Brahmaputra River System: review and...

The hydrochemical characterization and irrigation suitability assessment of the Ganges-Brahmaputra River System (GBRS) has immense importance for the livelihoods of people and ecosystem sustainability in the region. This study aims to assess the hydrochemical characteristics and evaluate the irrigation suitability of water in the GBRS by reviewing published literature of the major tributaries. The studied rivers were categorized into two groups namely Group-1 and Group-2 considering the similarities of climatic patterns, hydrochemical attributes, and drainage characteristics. The hydrochemistry of the river water was characterized by the Piper diagram, Gibbs plot, mixing plots, and ionic ratios. Furthermore, irrigation water qualities were evaluated by electrical conductivity (EC), sodium percentage (Na%), sodium adsorption ratio (SAR), magnesium hazard (MH), and Wilcox diagram. The results indicated that the hydrochemistry of the GBRS was slightly alkaline to alkaline (7.42-8.78) in nature. The average concentrations of most of the chemical attributes showed higher in Group-1, whereas the average concentrations of K⁺ and NO₃ ^- were found higher in Group-2. The average concentration of the major ions followed the dominancy order Ca²⁺ > Mg²⁺ > Na⁺ > K⁺ for cations and HCO₃ ^- >SO₄ ^2- > Cl^- > NO₃ ^- for anions in both groups. Gibbs plot and mixing plot indicated that carbonate rock weathering dominates the hydrochemical process, which was further confirmed by the Piper diagram and the ionic ratios. From the analyses of irrigational water quality, almost all the rivers (except Gomti River in terms of MH and Rangit River in terms of Na%) in the GBRS were found to be suitable based on EC, SAR, Na%, MH, and Wilcox diagram. Finally, the majority of river systems in the GBRS were characterized by carbonate dominated lithology and irrigational water quality is mostly suitable for utilization. This study could be useful for water quality management in the glacial-fed Himalayan river under the context of global climate change.