Simulation of soil water movement under subsurface irrigation with porous ceramic emitter

Abstract

Subsurface irrigation has been achieved by using ceramic emitters, pitchers, pots and ceramic tubes, which have gained a certain degree of interest in arid regions due to their efficient use of water. Research on the formation of wetting patterns around the ceramic emitter is essential for the design of irrigation system. In this study, numerical simulations were carried out to investigate the effects of emitter installation method, emitter buried depth, emitter structural parameters, irrigation doses and initial soil water content on the wetting patterns in clay loam with Hydrus-2D. Finally, two field application experiments were conducted to test the practicality and reliability of simulation results. The simulation results were in good agreement with the experimental data. Results showed, emitter installation method had the least effect on the wetting pattern. A 25cm buried depth would be suit for irrigating vegetables, a 45cm deep buried depth would suit for irrigating fruit trees. The structure parameters had a significant effect on cumulative fluxes and horizontal wetting front, the structural parameters (emitter length is 7.00cm, emitter external diameter is 1.25cm, and emitter inner diameter is 0.60cm) would be a better fabricate parameters for ceramic emitter. Wetting front increased with increasing irrigation doses and initial water content. To prevent percolation, when the initial water content was high, it should be better to cut down the irrigation duration of ceramic emitter. The field results indicated that Hydrus-2D could be used to investigate the suitable parameters for ceramic emitter in subsurface irrigation systems and determine the suitable arrangement and operation mode of ceramic emitter.