Simulation of soil wetting pattern with subsurface drip irrigation from line source

Abstract

The information on depths and widths of wetted zone of soil under subsurface application of water plays the great significance in design and management of subsurface drip irrigation (SDI) system for delivering required amount of water and chemical to the plant. A simulation model was developed using semi-empirical approach and dimensional analysis method for determining geometry of wetted soil zone under line sources of water application placed below the soil surface. The predicted values of wetted depth and width were compared with those obtained through field experiments conducted under sandy loam soil. Experimentation included determination of maximum depths and widths of wetted zone after 0.5, 1, 2, 3, 5, and 7 h of water application under laterals, porous pipes, and drip tape placed at 0.05, 0.10 and 0.15 m depths below soil surface. Statistical analysis revealed that there was no significant difference between predicted and observed values of wetted width and depth. The effect of discharge, depths of placement of lateral and duration of water application on wetted width and depth were similar for predicted and observed values. Predictability of model was expressed in terms of model efficiency, which was estimated as 96.4 and 98.4%, respectively, for prediction of wetted width and depth. This shows that developed model can be used to simulate wetting pattern under SDI system with line source of water application.