Using Hydrus-1D software to predict cumulative infiltration values for different soil textures

Four soil samples with varying textures (clay loam, clay, sandy clay loam, and silty loam) were collected from different locations in Nineveh Governorate, northern Iraq. Four different models were used to calculate air-entry values, including Lenhard (Ψe), Cornelis (Ψe1), Van Genuchten (Ψe2), and a modified model proposed in this study (Ψe.m) and a modified model proposed in this study (α). These values, which represent the inverse of the air-entry value (α), serve as inputs for the Hydrus-1D program. It is a difficult standard to measure and requires time and work to estimate. These models were used in the Brooks and Corey model (1964) to predict accumulated infiltration. It is expressed in the following formulas (IΨe, IΨe1, IΨe2, IΨem). As a new method in predicting accumulated infiltration values by using the Hydrus-1D program and comparing it with infiltration values measured in the laboratory and field. This a novel scientific enhances the program's functionality and updates input data to minimize errors. The results demonstrated that cumulative infiltration predicted by Hydrus-1D using hydraulic functions (,,) and the two constants in V.G model (α, n,) gave close values to the measured values. A high level of agreement was also observed between the predicted accumulated infiltration values (IΨe, IΨe1, IΨe2, IΨem) and the measured values when the same program was used, relying on the air-entry values of (Ψe, Ψe1, Ψe2, Ψe.m) as an alternative to the (α) value. The modified value in this study (Ψe.m) gave the best results to predict accumulated infiltration values when used in the Hydrus-1D program. We recommend adopting this modified value (Ψe.m) in Hydrus-1D to predict soil hydraulic properties.