Sensitivity analysis of the impact of soil hydraulic parameters on water infiltration from a single point source in membrane-hole irrigation

Abstract

【Objective】 Water infiltration in soil is an important process for designing drip irrigation and is impacted by soil properties. The purpose of this paper is to investigate the effect of soil hydraulic properties on water infiltration from a single-point source in membrane-hole irrigation. 【Method】 The studies were based on the HYDRUS-2D software, with the soil hydraulic properties described by the van Genuchten formula. 【Result】 ① The cumulative infiltration amount was negatively correlated with the parameter α, positively correlated with the parameter n, and was independent of the residual water content parameter θr. The horizontal advancement of the wetting front was negatively correlated to the parameter α and was independent of the parameter θr. The vertical advancement of the wetting front was negatively correlated to the parameter θr and positively correlated to the parameter n. At the end of infiltration, the volume of the wetted zone was positively correlated to the parameters θrand n. Change in the parameter n had the greatest effect on the size of the wetted zone.② The relative sensitivity of the cumulative infiltration gradually decreased with the increase in α; The positive perturbation of α affected the cumulative infiltration per unit membrane pore area to a weaker extent than the negative perturbation. α occurred in the negative perturbation, the relative sensitivity of the transport distance of the horizontal wetting front increased with the increase of the perturbation amplitude, and α occurred in the positive perturbation, the relative sensitivity of the transport distance of the horizontal wetting front decreased with the increase of the perturbation amplitude.③ When n was negatively perturbed, the relative sensitivities of cumulative infiltration per unit membrane pore area and vertical wetting front transport distance both showed a tendency to increase and then decrease with the increase of perturbation amplitude; when n was positively perturbed, the relative sensitivities of cumulative infiltration per unit membrane pore area showed a tendency to decrease and then increase and then decrease with the increase of perturbation amplitude. 【Conclusion】 Disturbing the parameter n has the most significant effect on water infiltration from the single-point source in membrane hole irrigation, while disturbing the parameter θr had the least effect.

Keywords

• model
• membrane hole irrigation
• single point source
• infiltration characteristics
• parameters