A new approach of developing subsurface drip irrigation (SDI) was introduced. The technique is called The Hydraulic Barrier or Bilateral SDI. It aims to enhance the water distribution in the root zone through burying a secondary dripper line beneath the primary one. The technique was tested through a field experiment on two crops and it was proved to have a noticeable effect on the crop yield. A numerical model and a computer application (Drip Chartist) was developed as well. This model is able to simulate surface and subsurface drip irrigation, with and without the hydraulic barrier, with and without the conventional physical barrier. The model was validated in field and through a comparison with previous trusted model (Hydrus 2D). Validation to the "Hydrus 2D" shows high coincidence between the two models. While the results show high correlations with field data with little under estimation. Several studies were performed on the computer model; which lead to important results in the drip irrigation systems design field.