Self-watering system for arid area: A method to combat desertification

One of the reasons for the rapid expansion of arid or semiarid areas is that the decline in the ground water level makes it impossible for plants to get enough water. In order to provide water sustainably for plant life, a self-watering system has been developed. This self-watering system, designed to collect and store rainwater, dew and groundwater, reliably provides water to the surface vegetation. The system consists of two parts: one is the original soil and the other is soil which is replaced by finer soils. The results of laboratory model tests and numerical simulations showed that the system continuously raises the ground water to a level higher than the maximum capillary height of sandy ground without the requirement for any extra energy input. The stable operation of the system mainly depends on unsaturated hydraulic conductivity, the soil water retention curve and the shape and the size of the area of replaced soil. Because the original top soil reduces evaporation, soil salinization is minimal. The evaporation rate is negatively and exponentially correlated to the thickness of the covered original soil. Both the T-type system and suspension-type system have been shown to have a larger net capillary storage capacity than the original sandy ground, with a specific value dependent on the soil water retention curve. The rate of water movement in the T-type system is five to six times higher than that in the suspension-type system. The water content of coarser soil near the finer soil is larger than that of homogeneous coarser soil. The numerical simulation results were in good agreement with the model test, and a case study with various potential transpiration rates was conducted to evaluate the dynamic performance of the system.