Modelling temperature-dependent hydraulic conductivity function of rooted soils

The performances of vegetated soil infrastructures (e.g., landfill covers, soil slopes and green roofs) are likely influenced by the temperature effects induced by decomposition of municipal solid waste, solar radiation, high air temperature and underground power cables. However, the dual effects of temperature and roots on soil hydraulic conductivity function (HCF) have remained poorly understood. In this study, temperature-controlled simplified evaporation experiments were conducted to measure soil water retention curves (SWRCs) and HCFs of rooted soils for temperature range between 24 and 54℃. Based on RT-SWRC model considering the physical occupancy of roots in pores (R) and temperature effects (T), a nonisothermal HCF model (i.e., RT-P model) was proposed by incorporating root-induced pore rearrangement (P). Furthermore, RT-P model was compared with Mualem’s model (i.e., RT-M model). Results indicated that saturated hydraulic conductivity (Ks) and unsaturated hydraulic conductivity (Ku) were increased by the roots. As the basis to develop RT-P HCF model, RT-SWRC accurately captured the temperature effects on SWRCs of both bare and rooted soils. For shrub-rooted soils in this study and grass-rooted soils from the literature, RT-P model provided a more accurate prediction for HCF than RT-M model under different temperatures, due to consideration of root-induced pore rearrangement.