Evaluation of Simple, Dynamic Soil Moisture Model

Abstract

The dynamics of soil moisture in the root zone is of fundamental importance in agricultural water management. A simple, yet physically based model is presented which describes the processes of redistribution of the soil moisture profile, drainage, and evapotransportation (ET) from the root zone. Using the sharp wetting front approximation, relatively simple expressions are derived that are explicit in parameters describing the soil and climate/vegetation properties. Application of these models using parameter values selected a priori indicates good results. Comparison of the redistribution and drainage models with laboratory data shows good agreement, as does comparison of the ET model with field soil moisture measurements. Uncertainty in soil parameters, root zone depth, and timing of irrigation applications affect model performance.