A distributed parameters model for soil water content: Spatial and temporal variability analysis

Soil water content is the main limiting factor for plant development under arid or semi-arid climates. Furthermore, it is a key factor in the physical, chemical and biological processes that occur in the soil-plant-atmosphere system; acting as a vector between these components. A distributed parameters model is proposed in order to describe the spatiotemporal variability of soil water content, linking the soil water content with the system inputs, such as rain or irrigation water, and the system outputs: evaporation, transpiration and percolation losses. Adding the lateral exchanges and the surface runoff makes it possible to take into account the terrain orography and tessellation. An experimental plot in SW Spain was used, where Soil Water Content was monitored with frequency-domain reflectometry sensors in several points, whereas the plot was divided into rectangular sectors. The rainfall was measured by a nearby agro-climatic station. A simulation environment was developed, using it to identify the model terms with experimental measurements and run other simulations for different climatic conditions.