Water cycle and water quality in the Lake Baiyangdian watershed of the North China Plain have undergone great changes due to over-pumping of groundwater and wastewater discharge. In this paper, hydrogeochemical data was collected to analyze the hydrochemical characteristics and geochemistry evolution of groundwater. The study area was divided into two typical parts. One was in the upstream plain area, where over-pumping had resulted in significant decline of groundwater level; the other one was located in the downstream area near the Fu River and Lake Baiyangdian (Lake BYD region). In addition to the natural weathering of minerals, excessive fertilizer was also a main factor of higher ion concentration in groundwater. According to studies, due to good permeability, these regions were easy to be polluted even with deep groundwater depth. However, upstream shallow groundwater and surface water, including lake water, domestic along with industrial wastewater were all sources of present shallow groundwater in the Lake BYD region. Results indicated that anthropogenic activities rather than minerals much matter to the groundwater in these regions. Particularly, wastewater largely decided the groundwater quality, which suggested that the management and restoration of surface water quality was crucial to groundwater protection.

Recharge and discharge, such as rainfall infiltration and evapotranspiration in vertical direction, are major processes of water cycle in the shallow groundwater area of the North China Plain. During these processes, soil water movement in the unsaturated zone plays an important role in the transformation from rainfall infiltration to groundwater. The soil water movement models were developed by using HYDRUS-1D software at two typical experimental sites in Cangzhou (CZ) and Hengshui (HS) with different soil, vegetation and similar climate conditions. As shown in the results, the comparison in precipitation infiltration features between the two sites is distinct. The soil water experiences strong evaporation after precipitation infiltration, which accounts for 63% of the total infiltration at the HS site where the soil is homogenous. It is this strong evaporation effect that leads to slight increase of soil water storage. At the CZ site, where the soil is heterogeneous, the evaporation effect exists from July to October of the simulation period. The total evaporation accounts for 33% of the total infiltration, and the evaporation rate is slow. At the end of the simulation period, the soil water storage increases and the water table decreases, indicating a strong storage capacity at this site.