Validation of Models for Simulating the Soil Moisture Characteristics

The determination of the soil moisture characteristic is a tedious, lengthy and costly laboratory methods. However, for the specific soil texture, once it is known, the soil moisture at various tension can be simulated through modelling approach which eliminates the requirements of performing the experiments every time. Therefore, the attempt was made for the determinations of the soil moisture characteristics during the year-2019 and validating the various models’ using these empirical data.

The present research covers the experimentation during the year 2019 for determination of the soil moisture characteristics and fitting the obtained empirical data to mathematical frames of the various models. The moisture characteristics was obtained by measuring different moisture content values at different suction values through two experiments viz. wetting cycle (Absorption phase) and drying cycle (Desorption phase). The desorption curve was obtained by using the pressure plate apparatus and the wetting curve was measured through the capillary rise open tube method.

The saturation, field capacity, permanent wilting, residual moisture content, void ratio and saturated hydraulic conductivity were found as 43.5%_v/v, 25.88%_v/v, 12.05%_v/v, 8.1%_v/v. 0.77 and 0.2808 m/day respectively. Among the fitted models, the van Genuchten model was found best fit to observe data to simulate the desorption and sorption phase of the soil moisture retention characteristics. The soil moisture retention characteristics of the sorption and desorption phases indicated a hysteresis of approximately two log cycles.