Simulation of Soil Water Movement in Upland Soils Under Pulse Irrigation using HYDRUS-2D

Purpose: The most important aspect in the design of drip irrigation system is the soil water distribution under the emitter, and numerical simulation is a fast and inexpensive approach to determine optimal irrigation management. The objective of this study was to investigate the soil water distributions at different distances between the emitter and the soil water sensor as a function of irrigation pulses using numerical simulation. Methods: HYDRUS-2D was used to simulate the spatial and temporal water movement within the soil domain. The simulations were performed with two lateral distances (20 cm and 30 cm) and three pulse conditions (2 min On and 1 min Off (2O1F), 1 min On and 1 min Off (1O1F), 1 min On and 2 min Off (1O2F)). The continuous application was the control treatment. Results: In the case of 20 cm, continuous application supplied water to crops quickly with the largest amount of irrigation. As the irrigation interval increased, the variation of water content and total irrigation amount decreased. In the case of 30 cm, the water took significantly more time to reach the distance. At the condition of 1O1F and 1O2F, the soil water content did not reach the target value (25%). Conclusions: The distance and irrigation frequency should be carefully considered when designing and managing a pulse irrigation system. These results support the use of HYDRUS-2D as an important tool for operating a drip irrigation system. © 2021, The Korean Society for Agricultural Machinery.