Development of a simplified continuous simulation model for investigating long-term soil moisture fluctuations

A deterministic continuous simulation model was developed to study soil moisture dynamics under any given soil, vegetation and climate conditions. The model is process-based and is formulated to simulate soil moisture at a point within the crop root zone on a daily basis throughout a growing season. This simplified one-dimensional model takes into account only the hydrological processes that operate in the vertical direction. Actual evapotranspiration is calculated as a function of potential evapotranspiration and soil moisture and is further adjusted to represent various plant growth stages. Leakage is modeled as a function of soil moisture. The model was successfully validated using climate and field data from the Guelph Turfgrass Institute and Environmental Research Centre in Ontario, Canada. The actual evapotranspiration and leakage calculation procedures included in this model emphasize the soil moisture regime's control over these two processes, and is different than the way other deterministic models represent these two processes within the water balance. The resulting model can be used as a tool for the assessment of the general soil moisture dynamics under the influence of soil, vegetation and changing climate conditions.