Spreadsheet Soil Moisture Dynamics

We monitored vertical profile of soil moisture and groundwater level at the paddy field, which has low permeability, during subsurface irrigation and drainage. For the prediction of soil moisture movement in this paddy field, we made numerical simulation model used spreadsheet Microsoft EXCEL 2010. This model was written in finite difference method (FDM) in steady state. We prepared several sheets to calculate those equations, e.g., potential (=total head), stream function, and so on. Input governing equation into each cells, we solved governing equations. Consequently we found that 1) irrigated water moved to plow layer through filter materials of main drain, 2)groundwater level changed quickly during irrigation and drainage, 3)the numerical model succeeded to represent the measured profile of soil moisture in reasonable.