Anticipatory Drainage Base Management for Groundwater Level Optimization

Controlled drainage is normally operated on a seasonal timescale to increase availability of water and to limit nutrient loss to surface water. It is conceivable that with more frequent, or even daily, management of the drainage base, controlled drainage can be both more efficient and effective. With the analytical successive steady state model presented here, rapid simulations of groundwater level and discharge as a function of time for a field under either regular or controlled drainage are feasible. The model includes effects of sudden changes in drainage base as well as damping and attenuation of dynamics by the unsaturated zone. It is validated against a numerical model and shows good agreement with numerical results. We demonstrate how this analytical model may facilitate anticipatory drainage base management based on ensemble weather forecasts, such that groundwater levels can be maintained at a theoretical optimal level.