Evaluation of numerical simulations of capillary barrier field tests

This paper presents a comparison of numerical simulations to the measured response of capillary barrier field tests. The simulations were of pilot-scale tests of four 7 m long, 1.2 m thick capillary barriers, two with 5% slopes and two with 10% slopes, with and without an included unsaturated drainage layers. The unsaturated drainage layer was included to encourage lateral drainage. The 5% sloped barriers were subjected to a period of constant infiltration for a period of 74 days, while the 10% system with the drainage layer had water added for 26 days and the conventional capillary barrier with a 10% slope was subjected to 43 days of infiltration. The numerical modelling was conducted using both drying and wetting soil moisture characteristic curves to determine their influence on the results. Differences between the field test and the model data were found, but in general the simulations appeared to adequately reproduce the response of the test systems. It was found that the use of wetting curve data provided a better fit to the field data, more accurately predicting the amount and timing of the percolate produced. © Rapid Science Ltd. 1998