Water transfer from the Yellow River in China impacts groundwater by changing the interaction between river and groundwater. The transfer alters the natural flow patterns, leading to higher river levels than groundwater levels. This creates a continuous connection between river water and groundwater, forming a groundwater mound in the riparian zone. The transferred water has high levels of certain chemicals, affecting the hydrochemistry of the receiving river. The impact on groundwater is mainly limited to the riparian zone and some lower areas, due to the high stream gradient promoting downstream groundwater flow and hindering lateral flow. The study shows that stream gradient plays a significant role in influencing the interaction between river water and groundwater.