Abstract
This research aims at developing a water retention technology utilizing the capillary barrier (CB) concept for irrigated ground in drylands using local geo-materials. To increase the water retention by CB, where plants can grow and survive at the pre-pre-planting stage in dryland, clarifying the ground conditions, including the layers’ thicknesses ratio, grain size distributions, and watering method through experimental and numerical approaches is considered. The main findings include 1) The experiment of the CB with drip irrigation revealed that the volumetric water content (VWC) at a depth of 200 mm exceeded the target value of at least 0.1 on the third day when watering twice a week with 1000 mL per irrigation. 2) From the numerical analysis, supplying water twice a week was enough to maintain the VWC within a depth of 200 mm higher than the targeted value of 0.1. 3) To maintain at least a target value extending up to 200 mm depth by supplying 1000 mL water twice a week, an optimum configuration with an effective grain size ratio of 5.2, mean grain size ratio of 3.9, and a thicknesses ratio of 0.1 comprised of coarse and fine sandy soil layers was confirmed.
