In recent decades, the decline of groundwater levels and the increasing salinity of aquifers have become among the most significant challenges in water resources management in arid and semi‑arid regions. Excessive exploitation of groundwater resources, expansion of agricultural activities, and land‑use changes are considered some of the most important factors intensifying this trend. However, the simultaneous assessment of quantitative and qualitative changes in groundwater and their relationship with land‑use patterns has not yet been comprehensively investigated in many plains of the country.

The aim of this study is to analyze groundwater level fluctuations and water salinity and to examine the role of land‑use changes in the Taybad and Qazvin plains. In this study, changes in groundwater resources were investigated in the Taybad plain during the period 2004–2022 and in the Qazvin plain during the period 2001–2023. For this purpose, groundwater level data, electrical conductivity (EC) measurements, and land‑use maps were analyzed using statistical analysis, spatial interpolation methods, and Geographic Information System (GIS).

The results indicated that in the Qazvin plain, the groundwater level declined by approximately 1 meter per year on average, while water salinity increased by about 6%. In the Taybad plain, a significant decline in groundwater levels was also observed, with an estimated average annual decrease of about 2 meters, and groundwater salinity showed an overall increase of approximately 3% during the study period. Furthermore, the greatest changes were observed in urban areas and agricultural lands, indicating the significant role of human activities and land‑use changes in intensifying groundwater depletion and aquifer salinization.