A Fluctuating Watertable Model for the Management of a Controlled-drainage/subirrigation System
A model (FWTMOD) was developed as a simplified method to predict daily changes in watertable depth for a controlled-drainage and subirrigation system. The model was based upon a fluctuating watertable equation derived by de Zeeuw and Hellinga of The Netherlands. This equation only requires two parameters to describe daily watertable fluctuation: (1) a reaction factor for a receding or rising watertable, and (2) a recharge coefficient to account for the portion of rainfall which causes the watertable to rise. For a given water management system, these parameters can be estimated from observed (measured) watertable responses for a representative number of rainfall events. The model was calibrated and tested to evaluate its application in simulation of a subsurface drainage system. Climatological and watertable data from a field drainage experiment at the Louisiana Agricultural Experiment Station’s Ben Hur Research Farm, Baton Rouge, Louisiana, was used to calibrate the model.