Analysis of groundwater dynamic variation and main control factors in Sanjiang Plain

Taking the Sanjiang Plain as an example, this paper selects typical profiles A-B along the groundwater flow direction. Based on the groundwater flow field in 1980 and 2019 dry seasons and the duration monitoring data of typical monitoring wells from 2018 to 2021, this paper applies GIS analysis, statistical analysis and comparative analysis methods to study the characteristics and causes of the difference in the dynamic changes of groundwater in the east and west directions in the Sanjiang Plain. The results show that: compared with 1980, the groundwater level in Jiansanjiang area has dropped 5-14m in total. The decline rate is reduced from 0.59m to 0.29m per year, and the groundwater level in the central and western plain area shows a small decline or upward trend. The groundwater regime in the central and western plain area is sensitive to artificial exploitation and atmospheric precipitation. The fluctuation range of groundwater level in the mainland can reach 9 meters, and that in Jiansanjiang area is mostly less than 1 meter. Influenced by the paleogeographic sedimentary environment, the characteristics of shallow surface "west sand and east clay" and the spatial differences of aquifer water richness are the main reasons for the significant inter annual and intra annual dynamic differences of groundwater in the east and west.