Spatial-seasonal variability in groundwater irrigation suitability for the sedimentary basin of North China: An assessment within a single hydrological year based on game theory and analysis of variance

Sedimentary basin of North China. Irrigation water quality is critical for sustaining crop production and ensuring global food security. To assess the seasonal suitability and variability of groundwater irrigation in the sedimentary basin of North China, 114 groundwater samples were collected in dry and wet seasons within a single hydrological year. A novel Irrigation Water Quality Index (IWQI) integrated with game theory was employed for a comprehensive appraisal of irrigation suitability. The hydrochemical analysis revealed that a low-mineralization HCO 3 -Ca type was predominant in both dry and wet seasons. Spatial classifications of electrical conductivity (EC), sodium adsorption ratio (SAR), permeability index (PI), residual sodium carbonate (RSC), and sodium percentage (Na%) showed that groundwater in both seasons was suitable for irrigation. However, salinity hazards were found in 15.79 % (dry season) and 14.03 % (wet season) of the samples, as indicated by the USSL diagram. On the contrary, the IWQI results classified all dry-season samples and 98.25 % of wet-season ones as having high or severe restriction for irrigation. This is due to the low ionic/electrolyte concentrations, which posed a long-term risk to soil structure and permeability despite having minimal immediate impact on crop growth. In addition, the seasonal effects on irrigation suitability were non-significant due to the primary recharge source of lateral inflow from the piedmont zone. To mitigate these risks, management strategies like amending irrigation water with calcium sources (e.g., gypsum) are recommended. The research findings provide important insights into managing groundwater sustainably for irrigation, although the analysis was limited to single-year data. For the development of a comprehensive irrigation suitability assessment approach, future studies should consider multi-scale water quality assessments, including different geospatial resolutions. • Hydrochemistry is primarily controlled by mineral dissolution and the HCO 3 -Ca type. • Most groundwater samples are suitable for irrigation with low saline-alkaline risk. • Low ion concentrations pose minimal risk to plant growth but may affect soil permeability. • Irrigation suitability has no significant differences between dry and wet seasons.