Background and Objective: The Qazvin Plain, one of the key agricultural regions in Iran, faces significant challenges affecting the quality of its water resources. These challenges include changes in land use (LU) and the expansion of activities such as agriculture and industry. Assessing, modeling, and predicting total dissolved solids (TDS) and the sodium absorption ratio (SAR) in groundwater—two critical parameters influencing water resource usability—can play a pivotal role in managing water quality in the region.
Materials and Methods: This study aimed to investigate and model the relationship between LU and water quality parameters. TDS and SAR values were first mapped using the inverse distance weighting (IDW) interpolation method. Land use in the Qazvin Plain was then classified using Landsat 8 satellite imagery and the supervised maximum likelihood classification method. Finally, geographic weighted regression (GWR) was employed to model and examine the spatial relationship between the LU distribution patterns in the Qazvin Plain and the groundwater quality parameters.
Results: The coefficient of determination (R²) for the relationship between SAR and LU was 0.74, while for TDS and LU, it was 0.81. These findings highlight a significant influence of LU changes on groundwater quality parameters in the study area.
Conclusion: The results demonstrate a strong correlation between LU and groundwater quality parameters. Moreover, the application of GWR proved effective in capturing spatial variations and providing accurate tools for analyzing these relationships. This approach can be instrumental in the sustainable management of water resources in the Qazvin Plain.
