Is deep soil water infiltration negligible during the winter frozen season in arid regions?

In arid regions of China, hydrological process is the most important influencing factor to local plants in this fragile ecological system. Quantification of precipitation, infiltration and evaporation, especially the deep soil recharge (DSR) over field scale, are among the key elements of concern in arid region research. This study uses a newly designed lysimeter to monitor DSR in mobile dunes in western China, and to analyze the relationship among precipitation, frozen soil depth of seasonal change, and infiltration amount. The conclusions are as follows. Although in arid regions of this study, the annual precipitation is only 48.2mm, there is still DSR to recharge groundwater, and the precipitation intensity threshold to generate DSR is less than 6.2mm. The light (less intensive) precipitation events in spring and winter frozen seasons can still generate a small but notable amount of DSR. The heavy precipitation events do not always generate significant DSR as the precipitated water may be redistributed in the form of surface run-off. Snow can also generate a certain limited amount of DSR, but such an effect has long been overlooked. The infiltration capacities of seasonal frozen soil and unfrozen soil are almost the same. The results of this study is very helpful for the accurate assessment of water resource in arid regions.