Numerical Simulation of Unsaturated Soil Water from a Trickle Irrigation System for Sandy Loam Soils

Abstract

Trickle irrigation is a system for supplying filtered water and fertilizer directly into the soil and water and it is allowed to dissipate under low pressure in an exact predetermined pattern. An equation to estimate the wetted area of unsaturated soil with water uptake by roots is simulated numerically using the HYDRUS-2D/3D software. In this paper, two soil types, which were different in saturated hydraulic conductivity were used with two types of crops tomato and corn, different values of emitter discharge and initial volumetric soil moisture content were assumed. It was assumed that the water uptake by roots was presented as a continuous sink function and it was introduced into Richard's equation in the unsaturated zone. Equations for wetted depth and radius were predicted. A good agreement was found between the predicted results with those obtained from the experiment field work. The maximum error of the predicted results were 23%, and 0.98 for modeling efficiency (EF), moreover, the root square error (RMSE) was below 0.95 cm.

Keywords

• numerical simulation, Richard's equation, HYDRUS-2D, root water uptake, soil moisture content.