Estimating Method of Maximum Infiltration Depth and Soil Water Supply.

The maximum infiltration depth and soil water supply must be evaluated in order to estimate the soil water resource use limit by plants and soil water carrying capacity for vegetation, and realize the sustainable use of soil water resources. However, there is no non-destructive method to estimate maximum infiltration depth and soil water supply. We conducted a simulated infiltration experiment and a long-term fixed-position investigation in situ in artificial Caragana shrubland at the Guyuan Eco-experimental Station in the semiarid Loess Plateau. The results showed that infiltration depth for one rain event was equal to the distance from the surface to the crossover point between the two soil water distribution curves with soil depth before a rain event and after the rain event. The soil water supply for one rainfall event was the difference in the soil water resources in the soil layers from maximum infiltration depth that occurred after a long period, and could be estimated by a series of two-curve methods. A maximum infiltration depth of 2.9 m occurred in the artificial Caragana shrubland. The results provide a foundation for controlling soil degradation and sustainable use of soil water resources in water-limited regions.