Study on Water Diffusion Characteristics
in the In-situ Soil of Exfiltration
Type Bioretention

Exfiltration type bioretention can collect rainwater runoff to recharge groundwater, but the water diffusion in the in-situ soil can have an impact on the foundation of adjacent structures (such as roads). Generally, the existing studies are primarily focused on the exfiltration of bioretention as an index of runoff control or the water balance. However, research is lacking on the diffusion characteristics of soil water content in different in-situ soils. Therefore, in this study, the VADOSE/W model was used to simulate the water transport process of bioretention ponds and in-situ soils, under long-term rainfall. The water diffusion characteristics of four in-situ soils were studied: silt loam (SL), loam (L), sandy clay loam (SCL), and sandy loam (SaL). The results showed that under 12 rainfall events, with a