Investigation of hydraulic characteristics and developed equations for subsurface leaky irrigation system

Subsurface leaky irrigation systems are one of the novel irrigation systems developed in recent years. In this system, the pipes are located below the soil surface and water is distributed in root zone with a very low pressure of less than one meter water column. This system can be widely used in small gardens with quantitative and qualitative water restrictions. Optimal design of these systems depends on the effect of different parameters on water infiltraion and wetting pattern. For this reason, the volume of water infiltration is investigated at different Subsurface leaky irrigation strategies. The inlet discharge and volume of applied water at each strategy differs from 0.1, 0.2 and 0.35 liters per second and 30, 60 and 90 liters, respectively. The humidity of the soil is also measured in wetting area at the end of each experiment. The results show that inlet discharge in feeding stage has dramatic effect on water infiltration, while the volume of applied water has more effects in discharg stage. Measurements of wetting pattern at the end of experiments also showed that water infiltration increased by 17% with increasing the inlet discharge into the system. The developed models in feeding phase and discharge and feeding phase in non-free surface flow had correlation coefficients of 0.69, 0.77 and 0.66, respectively, which show their higher accuracy in comparison with other phases.