Prediction of soil suction using measured climatic data

Abstract

This paper presents calibration and validation of a one-dimensional soil–atmosphere model created using the SVFlux software package for predicting soil suction changes based on the measured climate data at two Oklahoma Mesonet sites. The parameters for the soil water characteristic curves and the hydraulic conductivity function were obtained from published calibration studies conducted using laboratory test results on soil samples extracted from these sites. The plant cover quality, the root depth and the root uptake distribution function were first calibrated using 1-year data at one site. While a rectangular root uptake distribution function overpredicted suction at deeper layers, the triangular uptake distribution function overpredicted suction at shallower depths. In addition, reducing the root depth to 1 m improved the predictions at surface layers and led to overestimation of the suction at deeper layers. Based on the root mean squares of the differences between the simulated and the measured values and weighting the shallower depths more, a rectangular root uptake distribution function and a root depth of 1 m were selected to predict suction values at the calibration site and the second site for another year. Reasonable predictions of soil suction values at shallower depths were obtained at both sites.