Predicting the soil water retention curve from the particle size distribution based on a pore space geometry containing slit-shaped spaces

摘要

Traditional models employed to predict the soil water retention curve (SWRC)from the particle size distribution (PSD) always underestimate the watercontent in the dry range of the SWRC. Using the measured physical parametersof 48 soil samples from the UNSODA unsaturated soil hydraulic propertydatabase, these errors were proven to originate from an inaccurate estimationof the pore size distribution. A method was therefore proposed to improve theestimation of the water content at high suction heads using a pore modelcomprising a circle-shaped central pore connected to slit-shaped spaces. Inthis model, the pore volume fraction of the minimum pore diameter range andthe corresponding water content were accordingly increased. The predictedSWRCs using the improved method reasonably approximated the measured SWRCs,which were more accurate than those obtained using the traditional method andthe scaling approach in the dry range of the SWRC.