Abstract:
To investigate the dynamic variation characteristics of groundwater in Datong Basin from the dry season to the wet season, the authors used groundwater monitoring equipment integrated with modern monitoring data analysis methodologies, complemented by experimental techniques such as chemical analysis. The groundwater distribution characteristics and aquifer types in the study area were systematically analysed in this research, drawing on long-term monitoring data from 423 groundwater level observation wells and 91 water quality monitoring wells across the region. The conditions of groundwater recharge, runoff, and discharge were also incorporated to analyse the dynamic variation patterns of phreatic and confined water levels, water quality characteristics, and core driving factors. The findings areas follows: ① The dynamic changes of groundwater levels in Datong Basin exhibit multiple characteristics, including significant seasonal fluctuations and local specificity. Water level remain high during spring and winter, drop during summer when intensive extraction occurred, resulted in "V"-shaped pattern of change. The groundwater fluctuations are relatively large in the pluvial inclined plain and alluvial-lacustrine plain areas. And the groundwater depth is shallow (< 25 m) with gentle fluctuations in the basin center and river valley regions. In concentrated exploitation areas, the groundwater level changes frequently, with a variation range of 0.5~2.2 m. ② The groundwater environment in the study area has been affected by the combined pollution from industrial and agricultural activities as well as domestic sewage. The overall water quality is poor. The main indicators exceeding standards include total hardness, mineralization degree (total dissolved solids, TDS), nitrate, arsenic and so on. The spatial differences are significant, with the water quality of deep confined water being better than that of shallow groundwater, and high-quality groundwater is scattered in small amounts. ③ The exceedance of manganese and arsenic limits is co-driven by changes in redox environments and industrial-agricultural activities. The exceedance of total hardness and TDS limits stems from natural water-rock interactions, anthropogenic exploitation, and wastewater recharge. The exceedance of nitrate limits is primarily caused by excessive nitrogen application in agriculture and domestic pollution. The construction of this groundwater dynamic monitoring network has enabled long-term monitoring of groundwater within Datong Basin and its surrounding plain areas. It has clarified the dynamic variation characteristics of groundwater level and quality, as well as the core driving factors in the region, providing fundamental data for the development of groundwater resources in the area and supporting the supervision and management of groundwater resources.