Analysis of groundwater change around Yongding River since ecological water replenishment

To evaluate the variation in groundwater around river course after water replenishment, different methods are used to analyze groundwater level and water quality from 2019 to 2022 around the Yongding River． During water compensation, groundwater level along Yongding River exhibited a significant rebound trend, which is more significant in upstream areas． Spatially, closer the area to the river course, faster is the groundwater level response． The groundwater is weakly alkaline, with Ca²⁺, Na⁺ and \mathrmHCO_3^- as the dominant anions and cations． Under combined influence of multiple factors (ecological water replenishment and water quality, precipitation, hydrogeological conditions), the groundwater quality in the study area has improved significantly． Total hardness and nitrate nitrogen concentration of groundwater showed a downward trend, decrease in nitrate nitrogen was particularly significant．