A Spreadsheet for Estimating Soil Water Characteristic Curves (SWCC)

SWCC can be measured in the lab; however, due to the cost, time, and high variability in the results, empirical equations were developed using multiple regression approaches on databases consisting of a large number of measured SWCCs. The spreadsheet presented herein utilizes different methods that use basic soil properties, such as grain size distribution and Atterberg limits, to calculate the input parameters for van Genuchten and Fredlund and Xing equations. These parameters are required by numerical models, such as SEEP/W, to perform transient seepage analysis. The spreadsheet allows copying the generated curve data points as well as an input into the numerical model. The spreadsheet calculates the SWCCs using seven different methods for comparison. It also compares four closed form models, Gardner (1958), Brooks and Corey (1964), van Genuchten (1980), and Fredlund and Xing (1994), given the model parameters are known.