Impact of rainfall movement on soil crust development

The impact of rainfall event movement on soil crust development was investigated via laboratory experiments and physics-based hydrological-response simulation. Runoff and soil water content data were analyzed in order to study different crustal development periods under a variety of precipitation conditions. The results showed that the formation of crust significantly changed soil saturated hydraulic conductivity (Ks) and runoff, while a steady state, which could be broken by an extended period of raindrop impact, was found to exist for both the crust and, subsequently, runoff characteristics. The decrease in Ks was as high as 86% for downstream-moving events, and 72% for upstream-moving events, illustrating that the direction of rainfall movement has a more significant impact on crust formation than rainfall intensity and duration. As downstream-moving rainfall events may have a greater effect than those moving upstream, the development of a depositional crust before raindrop impact may play an important role in determining the final Ks value.