Modelling trickle irrigation: Comparison of analytical and numerical models for estimation of wetting front position with time

Irrigation practices that are profligate in their use of water have come under closer scrutiny by water managers and the public. Trickle irrigation has the propensity to increase water use efficiency but only if the system is designed to meet the soil and plant conditions. Recently we have provided a software tool, WetUp, to calculate the wetting patterns from trickle irrigation emitters. WetUp uses an analytical solution to calculate the wetted perimeter for both buried and surface emitters. This analytical solution has a number of assumptions, one of which is that the hydraulic conductivity (k) at the wetting front is a specific value. Here we compare the wetting patterns calculated with a 2dimensional numerical model, HYDRUS2D, for solving the flow into typical soils with the analytical solution. The results show that the wetting patterns are similar. Difficulties were experienced with getting stable solutions with HYDRUS2D for soils with low hydraulic conductivities.