Numerical Simulation of Soil Water from Subsurface Drip Irrigation for Fine and Medium Textures

Subsurface drip irrigation is one of the modern irrigation techniques that assist to control applied water by providing water to plant roots by drippers. Numerical simulation by using HYDRUS (2D/3D) was used to develop a formulas for estimating wetted area from subsurface drip irrigation together with water uptake by roots. In this study, two soil types, namely sand and sandy clay loam, were used with two types of crops, (tomatoes and onions). Different values of initial moisture content of soil, drip depth, and drip discharge were used in the simulation. The soil wetting patterns were analyzed each half an hour for three hours of irrigation time, and five initial soil moisture contents and different flow rates. To verify the results gained by applying HYDRUS (2D/3D) a field experiment was carried out to measure the wetted width and compare measured values with simulated values. Formulas for wetted width and depth were developed. The performance of the model was evaluated by comparing the predicted results with those obtained from field experiments. The modeling efficiency was greater than 98% and the root mean square error did not exceed 1.68 cm for both soils with good agreement. Keywords— Subsurface trickle irrigation, wetting patterns, wetted width, wetted depth, hydrus, soil moisture, sand soil, sandy clay loam soil.