Vertical Soil Moisture Heterogeneity Analysis and Model Reconstruction in Moist Zones of Aquaculture Pond Dikes Based on Multi-depth Soil Probe Observations

to continuously monitor soil moisture content and groundwater level over two aquaculture cycles (approximately 300 days). A layered Van Genuchten–Mualem model was used to construct the soil hydraulic functions. The results showed that during high water-level periods, the average difference in soil moisture content between surface and deep layers across the five sites reached 0.17 m³/m³. This led to an average error of 25% in the estimated hydraulic conductivity. After correction, the root mean square error (RMSE) of the model decreased from 0.031 to 0.014, indicating a clear improvement in model accuracy. This study proposed a moisture transport calculation method based on vertical gradient constraints, providing parameter support for seepage management and soil function evaluation in moist aquaculture zones.