Abstract: To examine dynamic soil moisture variations near the Wuqiangxi Reservoir dam, a soil moisture monitoring station within the area was selected as study focus. The measured daily rainfall and evaporation data were used to drive the HYDRUS-1D model for estimating soil hydraulic parameters. Subsequent simulations were conducted for soils at depths of 10, 20, and 40 cm to explore soil moisture dynamics and evaluate model performance. Results show a strong agreement (average coefficient of determination R²=0.74, average Nash efficiency coefficient is 0.71) between simulated and observed soil moisture values. Root mean square error ranged from 0.011 to 0.035 cm³/cm³. Soil moisture at 0-10 cm depth exhibited the most sensitive response to rainfall and evaporation, with significant fluctuations. During the main flood season (April to June), soil moisture remained consistently high. From July to December, soil moisture occasionally reached saturation levels due to heavy rainfall, leading to noticeable wet-dry cycles.Simulated values closely matched observed measurements,indicating the HYDRUS-1D model’s precision in dynamically simulating soil moisture, offering an effective approach for studying soil moisture dynamics within the research area.

Key words: soil moisture dynamics, near-dam area of reservoir, HYDRUS-1D model, parameter inversion, soil moisture monitoring station