Modelling vadose zone moisture dynamics in shallow water table settings with the Integrated Hydrologic Model: field-scale testing and application

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Reproducing the moisture retention behaviour of the vadose zone in shallow water table settings, especially for the near-surface water table aquifer of the Florida coastal plain, provides unique challenges for integrated hydrological models. A comprehensive distributed parameter model, the Integrated Hydrologic Model (IHM), is developed based on deterministic and physically based soil and vegetative properties. The theory and vertical behaviour of IHM is examined through comparisons with data collected at a study site in west-central Florida. The objectives of this exploration are to test a model of the vertical processes controlling water table behaviour, and to also investigate model parameter effects and offer recommendations for improvements and parameterization for regional model application. Rigorous testing is performed to better understand the robustness and/or the limitations of the methodology of the IHM for vadose zones. Simulation results indicate that IHM is capable of providing reasonable predictions of infiltration, depth to water table (DTWT) elevation response, evapotranspiration (ET) distributions from the upper, lower soil and water table while incorporating field-scale variability of soil and land cover properties.