Comparison of One- and Two-Dimensional Models to Simulate Alternate and Conventional Furrow Fertigation

Simulation models have recently been used in many studies for simulation of water flow and solute transport in soil under different irrigation systems. The objective of this study was to compare the HYDRUS-1D and HYDRUS-2D simulation models to simulate water and nitrate transfer for three furrow irrigation technologies [conventional furrow irrigation (CFI), fixed alternate furrow irrigation (FFI), and variable alternate furrow irrigation (AFI)] under fertigation practice. Filed measured data were used to calibrate and validate the one-dimensional (1D) and two-dimensional (2D) HYDRUS models. An inverse solution technique was applied to optimize soil-hydraulic and solute transport parameters to calibrate the models. The results indicated that the HYDRUS-2D model provided better performance to predict soil water contents, nitrate concentrations, and deep percolation caused by the geometry of the infiltration domain in furrow irrigation. Standard errors for HYDRUS-1D ranged from 0.107 to 0.170 for soil water content and 0.256 to 0.295 for soil nitrate concentration; whereas these values for HYDRUS-2D varied between 0.089 and 0.096 and 0.144 and 0.205 for soil water content and soil nitrate concentration, respectively. Application of HYDRUS-1D increased the risk of overestimation of nitrate leaching. CFI had higher water and nitrate deep percolation compared to AFI and FFI. Although the HYDRUS-2D model required much more computational time than HYDRUS-1D, using this model is recommended in furrow fertigation because of its more reliable and accurate simulation results.