Numerical analysis of sensor-based flood-floor ebb-and-flow subirrigation system with saline water

Abstract

ABSTRACT Ebb-and-flow is a well-known and common greenhouse irrigation system. In this paper, a specific numerical model for a sensor-based flood-floor ebb-and-flow irrigation system has been developed using one-dimensional Richards’ equation for water flow and two-site sorption advection-dispersion model for simulation of solute transport. The model was validated against analytical and numerical results proposed in the literature, and acceptable agreement was obtained in all cases. Maximum RMSE (MAE) was 0.053 m (0.273 m) for water flow and 0.021 (0.065) for solute transport. The model was then used for a parametric study of how different factors (such as salinity of irrigation water, triggering and cutoff thresholds, sensor position and flooding depth) would affect transpiration of sensor-equipped solitary pot under ebb-and-flow irrigation system for two different crops. It was revealed that sensor position and water salinity were significantly influential on transpiration of the pots. Finally, the synchronized sensor equipped-sensorless module of the numerical model was used to optimize the flood-floor ebb-and-flow irrigation system considering different factors using Taguchi approach. It was concluded that installing a water content sensor, whose triggering and cutoff thresholds were at −10 and −2 m, at the upper-half of the center-positioned pot would result in higher transpiration and lower unevenness of water distribution.